in this situation when climate change and mental illness due to overcrowding, pollution etc. would be at peak and ...... The flag leaf SPAD reading showed positive strong correlations with grain yield (Table 2). ...... New Zealand. 162. Chile. 180.
Agricultural-based Interventions for Sustainable Food Security & Climate Change Edit By Manoj Kumar Department of Agricultural Extension and Communication Modipuaram Meerut 250110 Dr. Ravindra Kumar Rajput Subject Matter Specialist (Soil Science) Krishi Vigyan Kendra, Mathura281001 (U.P.) Rahul Kumar Singh S.M.S. Agril. Extension MGKVK Gorakhpur U.P. Department of Extension Education NDUAT Kumarganj Faizabad 22422 Ripudaman Singh Department of Agronomy; Chandrashekhar Azad University of Agriculture and Technology, Kanpur, 208002 (UP)-India Rahul Kumar Verma S.M.S EHorticulture) K.V.K Lakhisarai B.A.U. Sabour Bhagal Pur 811318 Bihar India Hemant Kumar Department of Agronomy; Chandrashekhar Azad University of Agriculture and Technology, Kanpur, 208002 (UP)-India Robin Kumar Indian Institute of Farming System Research, Modipuram, Meerut-250110, U.P., India
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Contents Chapter
Page No.
1. Food and Nutritional Security through Technological Intervention of Vertical Farming of Vegetables in India
01-17
2. Effect of Weather and Climate on Crop Production, Soil Fertility and Incidence of Pest and Disease
19-33
3. Sustainable Agriculture to Ensuring Food Security
35-50
4. Synthetic Seed: A Novel Technology
51-68
5. Enhancing Nutrient use Efficiency through Next Generation Fertilizers in Vegetable & Field Crops
69-101
6. Male Sterility- The Genetic Mechanisms and It’s Uses
103-118
7. Impact of Climate Change on Temperate Vegetables
119-131
8. Environmental Effects of Irrigated Agriculture
133-145
9. Assessing Heterotic Potential in Major Field Crops and Animals
147-179
10. Conservation Agriculture: Towards A New Paradigm of Agricultural Sustainability
181-206
11. Conservation Agriculture Based Sustainable Water Management Technologies for Sustainable Rice Production
207-224
12. Soil Carbon Sequestration and Greenhouse Gas Emission with Conservation Agriculture for Climate Change
225-240
Chapter - 1 Food and Nutritional Security through Technological Intervention of Vertical Farming of Vegetables in India Authors Vineet Kumar Indian Institute of Farming System Research, Modipuram-250110, U.P., India Mukesh Kumar Department of Horticulture, Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut-250110, U.P., India Ashish Dwivedi Department of Agronomy Sumit Kumar Indian Institute of Farming System Research, Modipuram-250110, U.P., India R.K. Naresh Department of Agronomy
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Chapter - 1 Food and Nutritional Security through Technological Intervention of Vertical Farming of Vegetables in India
The Sky Greens Vertical farm The urban population in India which stands at 377 million is expected to grow by 404 million by 2050 (World Urbanization Prospects, 2014). The Page | 3
nutritional requirements of this increased urban population have to be met. Also, with growing affluence and increasing nutritional awareness among the city dwellers about nutrition, there will be increased demand for vegetables, fruits, eggs, meat, dairy products and even flowers. The direct consumption of food grains has decreased while the demand for food products higher up in the food chain, especially processed food, has gone up in recent years. On the other hand, about 65.5 million people live in urban slums and sprawls which lead to intra generational nutritional inequality. There is considerable food and nutritional insecurity in the urban areas the situation being worse in smaller towns. Especially vulnerable are women and children; about 50% of the women are anaemic, and undernourishment resulting in severe energy deficiency is rampant among women. People living in urban areas have much less control over the supply and quality of the food they consume as compared to the rural population. The food prices, especially those of vegetables, fruits and pulses, which heavily influence the quantum of their intake, are often subject to huge fluctuations due to many factors ranging from the vagaries of the monsoon to spread of diseases to the changes in price of crude oil in the international market and to the changes in policies governing import and export of agricultural commodities. They also have no control over the use of pesticides and other chemicals used in producing the food, which has serious implications for nutritional value and safety of the food consumed. Instances where farmers grow organic food for their own consumption and insecticide laden produce for sale have been reported. By the time it reaches the urban consumer the food will not be fresh and maybe refrigerated or artificially ripened. Use of chemicals to increase shelf life of the produce is also prevalent. Vertical farming (VF) will go a long way in addressing these concerns to a great extent. It can provide fresh produce to city dwellers without the need for resource intensive transportation, refrigeration and storage facilities, by reducing the time and distance from farm to fork. Being labor intensive it will also provide jobs and can become a source of income and thus contribute to poverty alleviation. Vertical farming has been found to be particularly helpful for poor women in urban and peri urban areas as it provides a means for meeting their families’ nutritional needs and getting some income as they work near their homes, simultaneously taking care of their families. VF has a significant role in urban environmental management as it can combat urban heat island effects and function as an urban lung in addition to providing visual appeal. Vertical Farming as a key element in food security strategies. However formal recognition of VF and its integration into the urban planning process is necessary for it to be successful.
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The world’s population is expanding at an annual rate of about 1.3% and is projected to double its present level of 6.5 billion by 2063. At the same time, rapidly warming climates are threatening to disrupt crop yields. With global agriculture facing some worrisome prospects – some experts predict serious food shortages by 2100 for half of the world’s population – new technologies are emerging with some possible solutions to the planet’s growing food needs. Vertical farming is gaining importance in the present scenario of lesser availability of land for cultivation coupled with increased urbanization and consequent fragmentation of land holdings. Further, conversion of agricultural land to non-agricultural purposes is posing a serious threat to agricultural production. Vertical farming is a technology that applies soil free methods like hydroponics and aeroponics to the growing of plants in spaces outside of traditional farms. Fruits and vegetables are literally grown vertically, making this type of farming ideal for urban locations and in areas lacking arable land. In these controlled environments, water and energy can be used efficiently and it can be easier to combat pests and plant diseases. With 50% of Indian population is projected to live in cities by 2050 thus in this situation when climate change and mental illness due to overcrowding, pollution etc. would be at peak and reliance on conventional farming would not be possible then vertical urban indoor farming or Roof Top Garden ( RTG) farming would be lucrative option by then. (*Vertical farming is defined as the concept of cultivating plants or animal life within skyscrapers or on vertically inclined surfaces, whereas building integrated agriculture (BIA) is the practice of locating high-performance hydroponic greenhouse systems on and in mixed-use buildings to exploit the synergies between the building environment and agriculture-like energy and nutrient flows) Verti crop is designed to increase production volume for field crops up to 20 times while using only 5% of the water usually needed in conventional farming. A 100 square meter machine can grow up to 11,200 plants at a time. Vertical farming solutions can serve the needs of vulnerable populations without a reliable food supply, help protect food and nutritional security and address environmental concerns like water consumption. Also, the technology can meet the needs of the human population while reducing the pressure to clear precious habitat for crops. While indoor farming is not a new idea – greenhouse-based agriculture has been around for centuries – vertical farming cranks things up several notches by potentially producing enough quantity to sustain large cities using resources mostly found within city limits. Some other benefits of the technology include year-round crop production, no weather related crop failures and the elimination of agricultural runoff. And since food Page | 5
grown in this manner can be produced in an urban area on a large scale, food transportation miles can be kept to a minimum, saving additional energy. Vertical farming might have started becoming popular internationally but in India it has not been very popular. Rural areas are providing food to the country’s population traditionally. The reasons behind this dependency are diverse at different places. At some place it is lack of government support and policies while at other places it is lack of interest among people to practice this change and taking time out of their daily life and getting involved in it. Lack of availability of land or open space or interest of government to identify such potential spaces. What is Vertical Farming? There’s far more pressure on even open field growers to continually grow. The land’s getting tired. There’s bigger disease pressure, so vertical farming really does give a very good environmental solution to areas that are looking to be self-sustainable. We’re going to struggle to supply enough food for the world in the next 20 years, so it’s utilizing space and it’s going upwards and it’s in existing spaces in big cities. From a logistical point of view, it’s really giving a good option. In another word, vertical farming is the practice of producing food and medicine in vertically stacked layers, vertically inclined surfaces and/or integrated in other structures (such as in a skyscraper, used warehouse, or shipping container). The modern ideas of vertical farming use indoor farming techniques and controlled-environment agriculture (CEA) technology, where all environmental factors can be controlled. These facilities utilize artificial control of light, environmental control (humidity, temperature, gases...) and fertigation. Some vertical farms use techniques similar to greenhouses, where natural sunlight can be augmented with artificial lighting and metal reflectors (Hix and John. 1974). It’s growing slowly, so we’re trying to understand exactly where the industry is going. We are really at the head of the curve and not waiting for people to come to us. How Does Vertical Farming Work? There are several different spaces that have been bucketed under the same vertical farming. So you’ have got vertical farming that’s taken spaces of warehouses in specific areas and they’re setting up. They’ve got a specific growing unit that stacks vertically. The commercial side of vertical farming is pretty cool, because it’s setting Page | 6
up the same growing system you can plug into your shed at home, and you can grow anything baby leaf. That system will allow you to continue to grow. And it’s in places that can’t grow open field vegetables because of the environment or there’s no land or no availability. These growers are setting up and building in these big factories, just utilizing old space. Food and Nutritional Security through Vertical Farming Urban food security depends on different factors: availability of food, access to food, and quality of food. With urban farming, all of these factors can be improved. All cultivation methods described can have a significant contribution to communities and their families’ food security. In respect to production for self-consumption, regardless of the income level, food and nutrition security can be improved by growing food in a home or community garden (Kortright and Wakefield 2011). By implementing urban horticulture in cities of the future, a greater scale of food security could be achieved. However, to gain global food security, attention has to be paid to both urban and rural agriculture. With urban horticulture alone, global food security cannot be achieved. However, urban food production on a large scale could take some pressure from rural agriculture. Urban horticulture could also help reach a certain balance between food availability in rural and urban areas. But even with a highly developed worldwide urban horticulture, rural agriculture will keep its significance concerning global food security (Dubbeling et al. 2010). Cuba is a very special example when it comes to the scale of urban farming. After the break down of the Soviet Union, Cuba had lost their major trade partner. As a consequence, urban agriculture evolved as the solution for self-sufficiency and food security. Because of the lack of inputs like fertilizers, pesticides, or fuel for food transportation into the city, labor-intensive, chemical-free, and urban became the main characteristics of Cuban food production. Problems and Possible Alternative Approaches in Vertical Farming in India In India and abroad as vertical farming is still not a reality as a large scale practice. The two major problems have been financial and technological feasibility. Since vertical farming or indoor farming requires contemporary building materials and renewable energy systems such as light shelves, light pipes and fiber optics which deliver natural light deep into buildings to provide energy for photosynthesis, and skilled workers to run it thus its rate of return does not seem profitable to investors. Where as in other hand conventional Page | 7
farming does not require either of it, but if one sees from the point of future then Z-farming (Zero-Acreage) and vertical farming can become the lucrative option for investors too. This is so because in scenario of climate change dependency on outside environment for conventional farming would be unfeasible also with global warming reaching its peak and urban heat island effect increasing in cities urban farming in way of roof top gardening (RTG) can be a possible lucrative option for the future. There are various types of agriculture and farming system in urban areas now a day. Some of them can be taken for vertical farming as a futuristic vision of India. The Agriculture land is reducing day by day and even its cost is increasing. The farming systems common to urban area can be analyzed (Lovell 2010). Vertical Farming – Possible Future of India The urban population in India expected to grow by 404 million by 2050 (World Urbanization Prospects, 2014). As cities in India like any other cities of the world are continually increasing in size with the increase in population thus it is quite possible in future that the types of land use practices will gradually encroach and engulf onto land which are currently utilized for agriculture (Pati et al., 2015). A. Vertical farming as way forward for increasing liability of future Indian cities If liability in cities is seen in Indian context at present then the condition is not virtuous, many metropolitan cities like Mumbai and Delhi are facing severe shortage of water, food and housing. Also with increasing population in cities its drawbacks related to overcrowding, pollution, lack of social concern and fading community bonding, culture etc. would be at major issue in the of land of diversity and culture. According to a recent report by the World Bank, the economic impact of the ambient air pollution in India is as high as atleast1.6% of its GDP. The problems of asthma and other lung related ailments are precisely due to the 'lack of lungs' in the cities along with air pollution. Thus reflecting these issues vertical farming can be a way out to increase the liability index in future cities of India as they can become the lungs of future vertical cities in buildings increasing community bonds in one hand and thus saving the existing forests from being cut due to need of land for conventional farming on other. B. Vertical faming as a water management tool for future. Water management would be a major issue for future cities of India, even Page | 8
at present cities like Mumbai, Pune and Delhi are facing severe shortage of water. According to the published report of Indian express of October 2015, Mumbai. The total usable water quantity in all the seven lakes supplying water to the city is 11 lakh million litres, three lakh million litres less than what was recorded on the 2014. Thus the city is currently facing a 15 per cent water deficit, which has forced the civic body to continue with the water cuts. With water shortage further degeneration, urban indoor faming can be a way out for ensuring food security in cities as tin case of aeroponics farmer’s use up to 95% less water than traditional farmers for farming thus further resolving issue of shortage of usable water for ensuring food security in the future. C. Vertical farming a possible replacement to conventional farming in future The amount of miles that food travels in cities from source of production will increase many folds in future if this way of dependency of cities for food and nutrition security on rural conventional farming will continue as today (today most of the food in cities is imported from other places). In this situation, future cities would have to produce their own food and with increasing land prices conventional land farming would not be possible but vertical farming or roof top farming( called as Zero –Acreage Farming as they are characterized by non-use of land) would be the possible approach and solution for nutrition to cities. We can analyses the available spaces in Delhi for vertical farming as the chart are showing the reduce spaces for vertical agriculture due to urbanization. So we have limited space for vertical farming so as considering the futuristic urbanism we have to adopt the option for vertical farming as well as incorporation of technology in urban agriculture areas. Farming have been around since early times for around of thousands of years and they are as essential for our daily lives as it was since early times and will continue to be vital and more demanding in future in one or the other way form providing food to supplying industries with much-needed resources including cotton, hemp and lumber to feeding to the mass urban population of the future. Vertical farming or Z-farming or farming on vacant open spaces, all can be favorable way for ensuring this demand of future in India and globally. With many countries of Europe, USA and Singapore has already risen to many folds towards this future farming, but in India it still has a long way to go ahead as vertical farming is still restricted to a few individually driven interest projects. With several benefits inherent in this method of farming E.g. It does not need an multi acre farm as it is vertical, it is good for environment as it can be used as water recycler (Some of the most recent vertical farms situated
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in the United States are also recycling waste material from the cities’According to report of Vertical Farming: Enter the Urban Farmer 22 January 2017, 19:00),grown food are completely free from pesticides thus organic and healthy, a more reliant and stable production source as it does not depend on outside environment. These are few benefits to count thus there is need of institutional support along with interest in people to participate in it and this possible by spreading awareness of benefits associated with it, strengthening policies like incentivizing farming for making it attractive to the urban dwellers, financial and technological support by government to developers of urban farmers or moving forward to a concept of „sharing backyard „ so that different communities can be reached in need of space or grower. One can see a progressive growth of vertical farming in India once all these are done and moving on this way forward this can act as urban regeneration tool for present and future cities by giving social (creating and enhancing social interaction, economic enhancing job opportunities in cities) and environmental benefits to the future cities. 1.
The urban hydroponics model of Vertical Farming is both presently realizable and profitable. The investment return is comparable to stock market averages.
2.
Properly implemented renewable energy sources can significantly reduce utilities expenditures, justifying their initial capital cost.
3.
Corporate and institutional investors are willing to finance Vertical Farming as a result of the operations significant secondary benefits.
4.
Vertical Farming presents a unique investment opportunity as it aims to revolutionize our understanding of food production and urban development.
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A View of Vertical Farming Once the experimental nature of vertical farms has been explored and the knowledge has been gathered to implement these effectively, they could be used to affect even more substantial gains with the ability to build and maintain these operations. Imagining a future where urban vertical farming becomes an important driver of the food production industry, the consequences on a social and political level would be difficult to predict, but they would be substantial. Major shifts in food distribution networks would ensue and therefore changes in political trade balances between nations and regions. Urban farms would compete and most likely gain the upper hand in the production of the majority of food in urban regions, leaving agricultural land to be used for more specialized uses, or to be returned to a natural state. Of course the production of food crops on land will quite likely remain financially beneficial as its primary investments are low, but as oil and energy prices rise, the transportation of these crops will gain an increasing share in the cost of traditionally cultivated food. On a sociological level people in dense urban environments would be partially reconnected with the cycle of resources that exists in the natural world. Waste would be locally treated and used to grow nutrients that are then consumed locally. The requirements of the vertical farms in terms of labor and maintenance would mingle a modern agrarian work force with that of more typical urban dwellers, which might prove for an interesting cultural interchange. It might serve to re-establish a certain respect and understanding for natural processes in the educational system as farms and schools can be co-located and other functions are integrated as well. It would not be a large stretch of the imagination to envision the merger of public places and food production, after all if Chinese gardens did it in ways we admire now, why not apply it to a new urban development? For developing worlds the farms could be a center for development, and
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substituting some high technology solutions with labor intensive solutions provide for employment for a substantial number of people. For developing areas it would mean a more reliable source of food, a more solid infrastructural foundation to build a society upon and a basis for a more solid economy. In addition it would likely reduce the amount of food related traffic within the city, although that is difficult to quantify. The quality of food could be regulated better and the water filtration properties of a vertical farm are paramount to healthy future development, this being a major issue in many developing areas (Specht et al. 2013). It could assist in providing employment for women in regions where women have lower (agricultural) social status and provide for a framework of reintegration of these classes and an emancipation of this status. Problems in Vertical Farming and Possible Solutions The need for vertical farming in India and the ways it can contribute to the economy and poverty alleviation in the section “Need for Vertical Farming in India”. However vertical farming is not without problems. Success of vertical farming depends on how well the issues regarding land, water and environmental pollution are addressed. The main issue with vertical farming is the availability of small piece of land for cultivation. In fast growing large cities where there is no more free space available, setting aside land for agricultural use is not feasible. Even where some free land is available the price can be so high that it is not possible for people to acquire the land for farming purposes. A study done on the effectiveness of the green belt as an urban growth boundary in Ghaziabad and Delhi found that there was no significant reduction in prices of land within and outside the city limits. Successive master plans have absorbed illegal and unplanned revenue layouts, i.e., private layouts that are culled out from agricultural land and converted for non-agricultural uses, into the city, often illegally and without necessary approvals etc (Despommier and Dickson, 2009). On the outskirts of many cities agricultural land is either converted for commercial purposes or bought and left fallow in anticipation of a price rise. Price of farmland has increased three to hundred fold in different parts of India. We found that the price at which the owners are willing to sell an acre of farmland 30 km from the Hyderabad airport is as high as Rs 3 crore and that for farmland 75 km from the airport is Rs 10-15 lakh per acre. Around 98 million out of total 120 million farm holdings in India belong to small and marginal farmers. Consumption expenditure of marginal and small farmers exceeds their estimated income by a substantial margin and therefore there is Page | 12
a high level of poverty among small farmers. The high price their land would fetch on selling compared to the meager amount they make from farming makes them sell the land and exit agriculture. In the process, the area under agriculture reduces. In many instances farmers have become laborers and farmland has become unaffordable to farmers in peri urban areas and even in villages. Some of them have sold their land to builders and live off rental income from apartments constructed on their land. Hence, it is not possible to buy agricultural land in peri urban areas and undertake farming as a profitable venture. Even the farmers who continue with agriculture and the new entrants would rather go in for high value cash crops than staples. This is where the government can step in to ensure that some land is set aside for farming purposes wherever feasible. Steps should be taken to stop speculative buying and illegal conversion of agricultural land. Strong enforcement of planning norms in the urban and peri urban areas is needed to prevent illegal conversion of agricultural land. It can also impose tax on vacant plots and houses to prevent unproductive use of land. Setting up schemes for leasing vacant plots for cultivation and encouraging the use of roof tops and backyards of houses and apartments as well as premises of schools and other institutions for farming are some of the ways space can be found for urban farming. Homeowners with space in their backyards or rooftops where they want to farm but are unable to do so themselves must be connected with people willing to grow food there for a fee. For example in Canada the ‘Sharing Backyards’ project connects homeowners who have a yard with people who want to grow food but do not own any land (source: Radio Canada). Large water requirement for crop production is another major hurdle for urban agriculture. Cities in India are struggling to meet the fresh water requirements of its residents for human needs. In many cities the utilities are able to provide only a fraction of the water requirements of its residents. The balance is met through wells drilled in the owners’ own premises or purchased from private tanker water suppliers who charge a large sum of money. Indiscriminate use of ground water for farming will lead to falling water tables thereby undermining the water security of the city. A majority of Indian cities are not located in water abundant regions. Due to encroachment of tanks and ponds and diversions of water most tanks and ponds in these cities have already dried up. Others are heavily polluted with waste and sewage and hence unusable. In many urban areas around the world including humid regions aquifers are getting depleted as pumping takes place within small geographical areas creating "cones of depression". For example, according to the Central
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Ground Water Board, India (2011), groundwater development in and around the Ahmedabad – Gandhinagar urban area has reached a critical stage while in Delhi, Ghaziabad and Bengaluru ground water is being pumped at a rate higher than the recharge rate with improper management of sewage causing nitrate pollution in the ground water as well. Using grey water and treated waste water for irrigation, a manifold increase in water productivity in agriculture as well as using lower quality water unfit for drinking for farming are the solutions to this problem. Farmers in Chennai have already been buying treated waste water and farmers along the Musi River in Hyderabad use the water from the river which is mostly effluent let into it by apartments, houses and industries. Given that 80% of the fresh water supplied ends up as waste water, treating the waste water to a level that makes it reusable for crop production, but will not cause health hazards to the farmers and consumers, will help close the loop in urban water management. Israel uses saline water and recycled sewage water for agriculture and has been conducting research on varieties and species of plants that are salt-tolerant and resistant to soil pathogens and on using grafted vegetable plants wherein a susceptible scion is grafted onto a resistant root stock. For example, cultivars resistant to Fusarium oxysporumf. Sp vas infectum race 3 (FOV3), which posed a threat to Pima cotton (Gossypium barbadense L), were developed which are superior in yield and quality compared to the susceptible ones, even in non-infested soil. Watermelons and cucumbers are grafted onto different root stocks to prevent damage by soil borne diseases. Improper and excessive use of pesticides and fertilizers in farming can pollute the soil and water in urban areas. Levels of pollution in cities are higher than in rural areas in the soil, water and air. Emissions from factories and automobiles lead to the presence of heavy metals and other toxic chemicals in water, soil and air while untreated and partially treated sewage lead to the presence of pathogens. This exposes the people who work in the urban farms and to a lesser extent the consumers of the produce to health risks. Suitable checks and precautions need to be exercised to prevent diseases triggered or produced by these pollutants. In earlier days, houses used to have kitchen gardens and fruit trees which at least catered partially to the needs of the family. These days most houses and apartments in cities do not have much free space around them. Even houses and housing societies that have some cultivable land undertake landscaping that involves non edible vegetation that emphasizes on beauty rather than utility. Builders, housing societies and individual owners must be encouraged and given technical support to include edible plants and fruit trees Page | 14
as part of their landscaping. Tax incentives can also be given to housing colonies and apartments to undertake landscaping that includes fruit trees, vegetables, herbs, etc. Factors Contributing To Success of Vertical Farming The reasons why people engage in vertical farming are varied. For the urban poor it is a means of getting vegetables and fruits which otherwise are beyond their reach and also making a living selling the produce. For others it is a way to deal with the fluctuating prices of vegetables, to consume fresh produce that has not been refrigerated or transported over long distances or to ensure that the food they eat is organic or pesticide free. Then there are some urban farmers for whom horticulture is a hobby. Vertical farming has been undertaken in cities with diverse socio economic conditions and having varying degrees of institutional support with different levels of success. While necessity was the factor that made VF successful in Havana the inability to procure pesticide free vegetables was what led the people of Kerala to take to organic farming. In a very densely populated city like Mumbai citizens are using innovative methods to have access to fresh produce. Farming in the slums of Cuttack, along the railway track in Mumbai and on the banks of the Yamuna in Delhi and Musi in Hyderabad helps the poor to meet their nutritional requirements and earn some money too in the process. The Pune City Farming Project initiated by the Pune Municipal Corporation did not take off and interest in kitchen gardens has been slow to catch on. In Kerala where production of organic vegetables has increased and expected to grow further, about 60% of the 33,310 households in Thiruvananthapuram who were given grow bags, seeds, plants and instructions by the State Horticulture Mission continued with rooftop farming (Down To Earth, 2015). Residents of Hyderabad can avail a subsidy for rooftop farming but the practice is not widespread. In many cities the poor urban farmers are fighting against odds to sustain their farming activities, relying on waste water like along the Musi River in Hyderabad or farming without legal sanction as on the banks of the Yamuna in Delhi. However, in cities like Chennai, Hyderabad and Pune there is institutional support but the number of residents taking up rooftop farming is less. The reasons can be varied including lack of space as in an apartment, lack of time or interest or lack of water. For example in a city like Bengaluru, many apartments buy water supplied through tankers for their daily needs. In the same cities where there is not much interest for roof top farming there are the urban poor who farm in the fringes of the city, Hyderabad and Chennai being
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examples. The farmers along Musi may be selling their produce at local markets thereby obviating the need for apartment dwellers to produce their own on their terraces. It can be seen that vertical farming is most successful when there is a need for and an interest in pursuing farming among a large section of the inhabitants of a city and there is institutional support for it. Institutional support is crucial for the farmers to get access to necessary resources. VF became extensively practiced in Havana because food availability declined by as much as 60% and residents had to produce their own food. More and more people started cultivating vegetables on their roof tops in Kerala because that was the only way they could ensure that the vegetables they ate were free from pesticides. In Mumbai farming on terraces and balconies helps recycle kitchen waste and provides fresh organic fruits and vegetables. In all cities there are poor people for whom vertical farming is a means to feed the family and a source of income. With increasing urbanization of India’s population it is essential that importance is given to vertical farming to improve food and nutritional security. At least partial self-sufficiency in food will protect the poor from the uncertainties in food availability brought about by climate variability, price fluctuations, changes in oil price and the like. At present our cities are faced with problems of water shortages, inadequate systems to manage municipal waste and waste water, air, and water and land pollution and urban poverty. These problems will only get intensified as the population increases. Changes in weather patterns like floods and droughts will add to these woes. The available information and infrastructure have to be streamlined towards making VF a viable proposition in India. It is also necessary to weed out inefficiencies and corrupt practices as is seen in the speculative trading in land and illegal conversion of agricultural land for other purposes and polluting our water bodies with untreated sewage. Once this is done we foresee a very positive future for vertical farming in the country. Advantages of vertical farming There’s no question that vertical farming has enticing potential benefits. The first is yield. Vertical farming can produce crops year-round, which increases production efficiency by a multiplier of 4 to 6 depending on the crop. There would also be less wastage and spoilage, as most of the crops could be sold fresh in a market or restaurant from the same facility. It’s estimated that 30% of harvested crops today are lost due to spoilage or infestation. Page | 16
Secondly, vertical farming has less risk associated with it. Big weather events such as floods, droughts, or storms can put a dent into agricultural activity fast, costing farmers billions of dollars. Farming indoors can reduce the risk of these types of events to as low as possible. Lastly, vertical farming is inherently more sustainable. By stacking farms vertically, the productivity per unit of land can be many times higher and arable land can be saved for other purposes. Further, there are no transportation costs to get the crops to market, and energy and water can be recycled within the building. Methane digesters can even help convert organic waste to energy to help power the building. References 1.
Hix, John. 1974. The glass house. Cambridge, Mass: MIT Press.
2. Pati, Ranjan; Abelar, Michael (27 May 2015). "The Application and Optimization of Metal Reflectors to Vertical Greenhouses to Increase Plant Growth and Health". Journal of Agricultural Engineering and Biotechnology: 63–71. doi:10.18005/JAEB0302003. 3. Despommier, Dickson 2009. "Growing Skyscrapers: The Rise of Vertical Farms."". Scientificamerican.com. Retrieved 2010-11-10. 4. Lovell ST (2010) Multifunctional urban agriculture for Sustainable land use planning in the United States. Sustainability 2:2499–2522. doi:10.3390/su2082499. 5. Kortright R, Wakefield S (2011) Edible backyards: a qualitative study of household food growing and its contributions to food security. Agric Hum Values 28:39–53. 6. Specht K, Siebert R, Hartmann I, Freisinger UB, Sawicka M, Werner A, Thomaier S, Henckel D, Walk H, Dierich A (2013) Urban agriculture of the future: an overview of sustainability aspects of food production in and on buildings. Agric Hum Values Springer Science+Business Media Dordrecht. doi:10.1007/s10460-013-9448-4 7. Dubbeling M, de Zeeuw H, van Veenhuizen R (2010) Cities, poverty and food—multi-stakeholder policy and planning in urban agriculture. RUAF Foundation, Rugby, p 173
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Chapter - 2 Effect of Weather and Climate on Crop Production, Soil Fertility and Incidence of Pest and Disease Authors Ajit Singh Department of Soil Science and Agriculture Chemistry SardarVallabhbhai Patel University of Agriculture & Technology, Meerut-250110, U.P., India S.R. Mishra Department of Agriculture Meteorology, N.D University of Agriculture & Technology, Kumarganj, Faizbada-224229 U.P., India U.P. Shahi Department of Soil Science and Agriculture Chemistry, SardarVallabhbhai Patel University of Agriculture & Technology, Meerut-250110, U.P., India Man Mohan Kumar Department of Soil Science and Agriculture Chemistry, SardarVallabhbhai Patel University of Agriculture & Technology, Meerut-250110, U.P., India
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Chapter - 2 Effect of Weather and Climate on Crop Production, Soil Fertility and Incidence of Pest and Disease
Introduction Climate/weather is an important component of crop production causing high variability in yield potentials even in highly favorable and high technology agricultural ecosystems. During the last 50 years, human activates all over the world have exploited the natural resources to meet their needs inducing a disturbed ecosystem with dangerous signal of continuous global warming and climate change scenarios. These activities have induced a global climate change of increase of 1 to 60C during the past 100 years resulting in extreme variability that 2002 and 2003 were declared as the warmest years (IPCC, 2001). A common conclusion globally has been felt that the expected impact of climate change on crop production may be small, with negative impacts over low latitudes and positive impact over high latitudes. Therefore, it is worthwhile to have a brief review on climate change complexities in odder to mitigate their adverse effects on agricultural production in the 21 st century. Currently 95 per cent of our food is produced by 30 different kind of plant genetically varieties, but with declining stock of wild plant varieties will limit the production of new strains (Kellogg and Schware, 1986). Howere, the weather conditions that prevail during crop growth period decides yield potentials, even though, all the other inputs required by the plant are supplied at the optimum level. A tremendous variation in the productivity of crops is because of the prevailing weather conditions. An occurrence of drought and outbreaks of pests and diseases cause severe crop losses. The farmers needs to be educated, well in advance, about the weather parameters, the occurrence of pest and diseases as well as their timely management practices to avoid the yield losses. A knowledge of weather parameters and their direct as well as indirect effects on crop growth and productivity. The common elements that determine climate are solar radiation, rainfall, atmospheric temperature, humidity and wind. All these have their own Page | 21
significance for the life of crop plants. The importance of an individual elements depends to certain extent on the intensity of the other elements. Options of cropping systems in different regions of the country and the management largely depend on the climate. Solar Radiation Solar radiation is the primary source of energy which supports all lives on the earth. Crop production is an exploitation of solar radiation. The atmosphere however, acts as a regulator in the types of solar radiation and none of the comic, gamma and X-rays reach the earth. The ultraviolet radiation of this segment reaching the earth surface is very low and is normally tolerated by plants. Solar radiation in the higher than visible wave length segment, referred to as infrared radiation, has thermal effects on plants. In the presence of the water vapors, this radiation does not harm plants, rather it supplies the necessary thermal energy to the plant environment. Temperature Air temperature is the most important weather parameter for plant life because of the following factors. 1. Physical and chemical processes within the plants are governed by temperature and these processes in true control biological reactions that take place within the plants. 2.
The diffusion rate of gases and liquids changes with temperature.
3.
Solubility of the different substances is dependent upon temperature.
4.
The rate of reactions varies with variations in temperature.
5.
Equilibrium of various systems and compounds is a function of temperature.
6.
Temperature effects the stability of the enzyme system.
The growth of higher plants is restricted to a temperature between 0 to 60 C and the optimum is 10 to 400C. Beyond these limits, plants are damaged severely and even get killed. The maximum production of dry matter occurs when the temperature ranges from 20 and 30 0C. 0
Soil Temperature In many instances, soil temperature is of greater importance to plant life than air temperature, e.g. beech and oak trees can withstand air temperature of -250C but roots of these cannot tolerate even up to -160C. Greater the soil Page | 22
temperature, higher will be the decomposition of organic matter. Humidity Relative humidity is associated with moisture content of air. As the atmospheric humidity increases, the temperature decreases. This phenomenon increases the heat of the leaves because not much of heat energy is used under reduced transpiration. A moderately high 60-80% R.H. is conducive for growth and development of plants. A very high R.H. is beneficial to maize, sorghum, sugarcane, etc., while it is harmful to crops like sunflower and tobacco. It is always safe to have a moderate R.H. of above 40%. Rainfall Precipitation is the primary source of water to the earth. About 75% of the global area depends solely on rain for production. In India, rainfed agriculture is carried out in about 70% of the cultivable area which contributes about 42% of total food production. When the rainfall is less than 500mm, only pasture grasses can be raised. If the rainfall range between 500-700mm, a single monsoon crop with intercrops is raised. When the rainfall is 750-900mm, two crops are raised with some adjustment in the sowing time. In areas of more than 900 mm rainfall, two crops are raised. Wind Wind influences plant life, both physiologically and mechanically. The influence is more pronounced on plants on flat lands near the sea coast and or the slopes of mountains. The influences of strong wind pressure from fixed directions, the normal form and position of the shoots are permanently deformed. Another severe injury to plants caused by strong wind is lodging. This injury is common in paddy, maize, sorghum, wheat and sugarcane. Strong wind breaks the twigs and sheds fruits from plants. Further, crops and trees with shallow roots are often uprooted. When the plants cover is not thick, strong winds remove the dry soil, exposing their roots and killing them, eroded materials from one place becomes a hazard to the existing small plants in places where it is deposits. This deposited material reduces the aeration around the roots and plants. Impact of Climate Change on Crop Production on India In an agrarin contury like India with staggering increase in population and food demands, even a slight decline in annual food production is a matter of great concern. Rice and wheat are the most dominant cereal crops of India, a Page | 23
picture of the likely performance of these twocrops is emerging from results os studies which have conducted during the recent years. Rice Murty (1991) studied the imapct of likely of the global weather and associatrd changes in carbondioxide, temperature, UV radiation, drought spells, flooding influence on tropical rice. The dry season tempertature may exceed the thershold value of 350C during anthesis of rice resulting in acute spikelet sterlity. These affects are further aggravated by low solar radiation during wet season. Mathauda and Mavi (1994) simulated the variabilities in the rice yield in the India Punjab under different climate scenarion. The simulated rice yields are in close agreement with the finding of the above said study. The decline in grain yield under the warm climate scenarios indicated the dire need for selecting/evolving suitable genotypes which will have the potentials to produce as good as under persent climate conditions. Wheat Abrol et al (1991) analysed the role of expected increase in CO2 levels concurrent with the increase in mean annual temperature above the existing normal seasonal fluctuations on the wheat crop in India.thus the situation will not be grim since such an increase in CO2 concentration would conterbalance the delerious effect of temperature on grain yield. Mavi et al (1993) conducted a study to assess the impact of climate changes on the performance of wheat crop in Punjab through the simulation technique. Historical daily weather data from November to April were collected for the 30 years period (1960-61 to 1989-90) on solar radiation. Maximum and minimum temperature and rainfall. Physical Properties and Mechanical Composition of Soil Soil is a three phase system comprising of the solid phase made of mineral and organic matter and various chemical compounds, the liquid phase called the soil moisture and the gaseous phase is called the soil air. Mechanical composition of a soil refers to its solid phase composed of mineral fraction. The components of fine earth are sand, silt and clay. Soil texture: The relative prortion of sand, silt and clay determines the soil texture. The term soil texture is an expression of the predominant size or size range of the particles. Soil structure: The arrangement of individual soil particles with respect to each other into a pattern is called soil structure. Soil structure has a Page | 24
pronounced effect on soil properties, viz, erodibility, porosity, hydraulic conductivity, infiltration and water holding capacity. Effect of Weather and Climate on Soil Fertility Red Soil (Alfisol) Red soils are agriculturally important found in major portion of dry lands. They are generally low in organic matter, available N and P. Soil pH ranges from 5.8 to 6.7. Rooting depth of crops is limited by the presence of compact subsoil. Many crops are susceptible to even moderate droughts. These soils are having the characteristics of rapidly sealing the surface after the rainfall. Water supply in the soil is reduced by limited infiltration due to lower conductivity. Problem of crusting affects the crop establishment. Soil moisture deficit is the major factor related to rainfall climatology affecting crop production. Soil erosion is the major factor reducing the fertility due to highly variable seasonal rainfall pattern. Black Soil (Vertisol) Black soils in India cover an area of about 72.9 m. ha which accounts for 22.2% of the total geographical area of the country. These are generally rainfed and experience considerable fluctuations in crop production due to climate variability. The clay content of the soil ranges from 40 to 60%, occasionally going to as high as 80%. Organic carbon content remains low ranging from 0.3 to 0.7%, pH of the soil normally ranges from 7.5 to 8.6%. The cation exchange capacity is 35-50 meq/100g. Inversion takes unique feature of the vertisols or deep black soils. Vertisols are necessarily deep. The soils invariably have wide and deep shrinkage cracks on the surface that changes with variation in the soil moisture regime. The cracks remain open depending on soil moisture and evaporation. The deep black soils, because of their high clay content, expanding nature of clay and depth, have a very high water holding capacity enabling crops to with stand drought at different stages of the crop. Laterite Soils The texture of the topsoil is loamy or clayey with many concretions. Laterite soils are generally associated with undulating topography in regions with a relatively high annual rainfall. These soils cover 13 m. ha in India. These soils are mostly dominated in hilly and high rainfall regions and slightly acidic in nature due to leaching of bases. They are rich in Iron and Aluminum. Alluvial Soil They are generally loamy sands or sandy loams, very deep with moderate Page | 25
clay content. These soils are having firmly high water holding capacity. The drainage characteristics are highly varying. Water stagnation is the major problem affecting crop productivity during heavy rainfall seasons. Sierozemic Soil These soils are sand, loamy sand and sandy loam in texture. Soil erosion through winds is common. Since these soils are light textured, water and nutrient holding capacity is less. Sub-soil Salinity is common due to extreme aridity. Kharif or Rabi cropping is possible in deep soils. But in loamy sands and sand, only the Kharif crops can be raised. Submontane Soil The soils are silty loam in texture and are medium to deep. Landslides and soil erosion are common. High rainfall lead to heavy soil erosion and major portion of top fertile soils are lost. Incidence of Pest and Disease Considerable crop losses caused due to pests and diseases in the humid and sub humid tropics. Many of the restrictions on productivity and geographical distribution of plants and animals are imposed by pests and diseases. The geographical distribution of pests is mainly based on climatic factors. The climatic conditions show a gradient from place to place and there is a related gradient in the abundance of a particular pest / disease. The periodic or seasonal nature of incidence and out breaks of several pests and diseases of many crops can be ascribed to weather conditions as the triggering factors. These epidemics of diseases are principally weather dependent, either in terms of local weather conditions being favourable for growth and development of the casual organisms or the prevailing winds helping to disseminate airborne pathogens or spores of diseases such as mildew, rusts, scabs and blights. The migration and dispersion of insect pests depend on the wind speed and direction besides the nature of air currents. Some plant pathogenic viruses suitable for the development of these vectors favor the transmission of such diseases. A surfeit of pests and diseases, which infest plants are kept in chock by seasonal fluctuations in atmospheric temperature or relative humidity and other weather factors. Insect pest outbreaks occur as a result of congenial weather conditions, which facilitate their un-interrupted multiplication. The weather and climate greatly influence the quantity and quality of food provided by the host crops to the associated species of pests. The abundance or otherwise of the pestiferous species is thus dependent on climatic Page | 26
conditions, indirectly also. The surface air temperature, relative humidity, dew fall, sunshine, cloud amount, wind, rainfall and their pattern and distribution are the primary weather factors influencing the incidence or outbreaks of pests and diseases of crops. In the humid tropics, the weather variables namely air temperature, intermittent rainfall, cloudy weather and dewfall may play a crucial role in the outbreaks of pests and diseases. The impact of various weather components on pests and diseases is experienced in a location and crop specific manner. Among the major pests associated with crops, insect, mite and nematode species are of a serious nature in terms of their abundance and damage potential. If the occurrence of pest / disease in time and space can be predicted in advance with reasonable accuracy on the basis of relevant weather parameters, appropriate and timely control measures can be programmed. Appropriate insecticide / fungicide interventions can certainly reduce the pesticide load in the environment and the related pollution and health hazards. Weather Pests and Diseases Weather and climate play an important role in the pest and disease outbreaks in crop. There exists a significant relationship between the plant diseases and prevailing weather conditions. Weather is the main vase for season to season variations in the severity of diseases occurrence. Weather fluctuations are the main source of uncertainty in the crop production. Pest and diseases have direct influence on the crop plants. Every year considerable losses in the crop production are caused by the pests and plant diseases all over the world. Therefore, the control of pest and disease is helpful for reducing the losses in the grain yield of the crops. Plant diseases are influenced by microclimate within the crop field, which itself is controlled by weather conditions. Effect of Weather Parameters on the Plant Diseases 1.
Temperature
2.
Humidity and Precipitation
3.
Light
4.
Wind
5.
Rain
Pest and Disease Forecasting Pest and diseases forecasting is based on the recorded day of various weather parameters in relation to their incidence. Most of the pests and Page | 27
diseases are directly influenced by various weather parameters. Every organism is sensitive to the variations in weather conditions. The development and multiplication depend upon the current weather conditions as well as the behaviour of the weather in the next few days. Wheat Rust In India, during summer season, high temperature do not allow either the wheat crop or the rust to survive in the plain areas. Climatic conditions are favourable for the wheat rust to survive in the Himalayan region during summer on the host plant of Barberry. Wheat rust can move from Nilgiri hills towards north in central India (Joshi and Palmer, 1973). Different Type’s Wheat Rust Wheat rust can be divided into three types 1. Yellow rust- Yellow rust is mainly confined to the northern parts of India due to its low temperature requirement. In the wheat season, the weather conditions are favourable for the yellow rust in north India. Yellow rust spores move from Himalaysto plains of north-west India along with northerly winds. Weather Conditions Favourable for the Appearance of Yellow Rust Are Given Below:a)
Mean air temperature should range between 9 to 13 0C
b) Relative humidity should be more than 70per cent c)
There must exist partly cloudy conditions
2. Brown rust- Brown rust can survive over a wide range of temperature. Therefore, northern and southern hills act as source regions of infection. Brown rust can appear in the entire wheat belt under favourable weather conditions. This rust appears in Punjab the month of February. Weather Conditions Favourable for Its Multiplication are Given Below:a)
Mean air temperature between 15 to 200C should prevail for a week.
b) Relative humidity should be more than 70 per cant c) Intermittent cloudiness must exist in the end of January or first week of February. 3. Black rust- Though the black rust can survive in the northern hills throughout the summer season, the source of inoculums concerned in the epidemiology of the black rust is the Nilgiri hills of the south. This rust appears in Punjab usually by the end of February to mid-March. Page | 28
Favourable Weather Conditions for Its Multiplication are Given Below:a)
Mean air temperature should range between 16 to 27 0C.
b) Relative humidity should be more than 70 per cent. c)
There should be excessive dew.
Light Blight of Potato During winter season, western disturbances cause cloudiness, rains dew and fog over North India. When these weather parameters become favourable, late blight of potato appears. But during summer season, favourable weather conditions are found in the hilly areas of north India. Therefore, incidence of late blight of potato is common in hilly regions. Forecast of Late Blight of Potato Several studies have been conducted to predict late blight of potato by using various environmental conditions. Late blight of potato could be predicted by using synoptic charts and warning were issued four days ahead for spraying the potato crop against late blight (Bourke, 1957). Disease of Rice Several studies have been conducted to identify the weather conditions which are favourable for the incidence of may rice diseases. Blast Disease of Rice The Weather Conditions Favourable for the Incidence of Disease are Given Below i.
Minimum temperature should be less than 260C.
ii.
Relative humidity should be more than 90 per cent.
Stem Rot of Rice Following Weather Conditions are Favourable for the Incidence of the Diseasei.
Temperature should range between 19-370C during summer season and 17-260C during winter season.
ii.
High relative humidity should persist.
iii. Rice crop grown under irrigated conditions is more susceptible to this disease.
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Bacterial Leaf Blight Weather conditions favourable for the incidence of the disease are given below (Lenka, 1998): i.
Temperature should range between 30.4-32.70C.
ii.
Relative humidity should range between 86-93 per cent.
iii. Sunshine hours should range between 3.3-7.8 hours per day Diseases of Groundnut Leaf Spot:- It is an important disease of groundnut. Leaf spot may be of two types. Early leaf sport and late spot. Generally these diseases can damage the crop by 10-15 per cent. It has been observed that primary source of infection is the plant residue left in the fields. Dew, fog and rainfall are important sources of moisture, which keep the leaves wet. Losses may be more in those areas where the crop is grown under irrigated conditions because of higher humidity. Favourable Weather Conditions for the Appearance of Leaf Spots are Given Below: i.
Temperature should range between 22-350C.
ii.
Humid conditions caused by excessive rainfall should persist.
iii. Higher duration of leaf wetness due to dew, fog and rainfall. Diseases of Pulses Ascochyta Blight of Chickpea Favourable Weather Conditions for the Disease are (Singh et al, 1982): i.
Temperature should be around 20-250C.
ii.
There should be high and prolonged rainfall.
iii. There should be intermittent cloudiness and dew. iv. Wetting, splashing rains and strong winds are favourable for disease spread. Lentil Rust This disease appears at flowering and podding stage in the form of pycinia and aecia. Aeciospores germinate at 17-220C and infect other plants forming either secondary Aecia or Uredia depending upon prevalent temperature of 250C (Singh and Sharma, 2005). Cercospora Leaf Spot of Mungbean and Urdbean Page | 30
Weather Conditions Favourable for the Disease are Given below (Soob and Singh, 1984): i.
Mean temperature should be between 22.5-23.50C.
ii.
Relative humidity should range between 77 to 86 per cent.
iii. Sunshine should be more than 5 hours per day. iv. There should be more number of rainy days. Phytophthora Blight of Pigeonpea Favourable Weather Conditions for the Incidence of Disease (Agarwal and Khare, 1987) i.
Humid weather conditions and temperature ranging from 20-250C are favourable for the initiation and rapid development of the disease.
ii.
Maximum disease severity occurs when maximum temperature is around 270C and relative humidity should be around 92 per cent during rainy days.
Meteorological Factors in Relation to Pest out Break Some of the important pest of those crop are discussed here in relation to their weather requirement. Rice stem borer:- High stem borer infestations are noted in paddy planted from October to January and low infestations on crop planted from June to October. The months are active between a temperature range of 19330C and the maximum number of eggs are laid at 29-300C and 90% RH. Rice gall midge:- Favourable conditions for infestation were at T min= 19.8 C, T max= 35.20C with relative humidity 89.94% and mean rainfall 4.5 to 62.5 mm. (per 5 day period). 0
Brown plant hopper:- During monsoon dry and warm period proceeded by heavy precipitation of more than 30 mm per week for at least 2 weeks during September with T min in the range 21-230C, relative humidity of 6570% and 7-9 sun shine hours during dry spell. Rice grasshopper:- The dry and warm weather during hatching and moulting phase favours the multiplication of the pest causing a heavy outbreak. Cotton spotted bollworm:- During boll formation stage (in July/August) the infestation occurs at a rapid rate. The optimum value of RH-I is 95-100%, BSS is 5-7 ha and week rainfall of 17-210 mm for infestations. In Page | 31
October/November, the larval activities are more when Tmin is ranging between 19-200C and Tmax is in between 30-320C. Sugarcane shot borer:- Favourable conditions are T max=37.8-41.40C, T min=24.4-31.10C RH-I= 23-73%, RH-II=16-61%. Colorado potato beetle:- Very active at temperature range 16-270C. Annual rainfall of 600-1500 mm is favourable for its optimum development. Egg laying is maximum at 250C and considerable mortality occurs at 30 0C. Incubation period is 5 days at 300C and 19 days at 120C. A temperature of 380C is lethal for larva. References 1.
Abrol, Y.P., A.K. Bagga, N.V.K. Chakravarty and P.N. Wattal. (1991). Imapact of Rice in temperature on the productivity of Wheat in India, proce symp. On imapact of Global climatic changes on Photosynthesis and Plant Productivity. Oxford & IBH. 551-552.
2.
Agarwal, S.C and Khare, M.N. (1987). Development of stem blight of pigeonpea in relation to environmental factors. India. J. of Mycology and Plant Pathology 17, 305-309.
3.
Bishnoi, O.P. Applied Agroclimatology. Oxford book company Jaipur India.
4.
ICAR.
5.
IPCC, 2001. Climate change. The Scientific basic (eds). Houghton, J.Y. Ding Griggs, M., Nouger, X., Dali; K. Mexkell; C Johnson. Combridge University Press. Cambridge U.K.
6.
Joshi, L.M and Palmer, L.T. (1973). Epidemiology of stem, leaf and stripe ruts of wheat in northern India. P.L. Dis. Reptr. 57: 8-12.
7.
Kellogg William and Schware Robert. (1986). Climate change and society p.p 68-69. Boulder, Co. Westview press.
8.
Lenka, D. (1998). Irrigation and Drainage, Kalyani Publishers, Noida.
9.
Mahi, G.S. and Kingra, P.K. Fundamentals of Agrometeorology. Kalyani Publishers.
10. Mathauda, S.S and Mavi, H.S. (1994). Imapact of climate change in Rice Production in Punjab (India). Climate change and rice symp. International Rice Research Instiute, Manila, Philippines. (Submitted) 11. Mavi, H.S. Introduction to Agrometeorology (second edition). Oxford & IBHPublishing CO. PVT. LTD. Page | 32
12. Mavi, H.S., Singh, G., Mathauda S.S., Singh, R., Mahi, G.S. and Jhorar, O.P. (1993). Climate change and wheat yield in the Punjab (India) Proc. Symp. On climate change Natural Disaters and Agricultural Strategies. BHU, Beijing: 58-65. 13. Murty, K.S (1991). Impact of Global climatic change on photosyn thates and productivity of rice. Proce Symp. on Impact of Global climatic changes on photosynthates and plant productivity. Oxford & IBH. 673683. 14. Singh, G and Sharma, Y.R. (2005). Disease management in pulses. In pulses (Eds. G Singh, HS Sekhon and JS kolar). Agrotech publishing Company, Udaipur: 485-517. 15. Singh, G., Singh, K and Kapoor, S. (1982). Screening for sources of resistance to Ascochyta blight of chickpea. International Chickpea Newsletter 6, 15-17. 16. Sood, V.K and Singh, B.M. (1984). Effect of sowing date and row spacing on the development of leaf spot (Cercospora canescens) in urdbean. Indian Phytopathology 37, 288-293. 17. Varshneya, M.C. and Pillai, P.B. Text book of Agricultural Meteorology. Published by
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Chapter - 3 Sustainable Agriculture to Ensuring Food Security Authors Ankit Sharma Agricultural Process and Food Engineering Yogendra Singh Agricultural Process and Food Engineering Ashish Dwivedi Department of Agronomy; Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut-250110, U.P., India
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Chapter - 3 Sustainable Agriculture to Ensuring Food Security
Background A sustainable agriculture is a system of agriculture that will last. It is an agriculture that maintains its productivity over the long run. Sustainable agriculture is both a philosophy and a system of farming. It has its roots in a set of values that reflects an awareness of both ecological and social realities. It involves design and management procedures that work with natural processes to conserve all resources, minimize waste and environmental damage, while maintaining or improving farm profitability. In practice such systems have tended to avoid the use of synthetically compounded fertilizers, pesticides, growth regulators, and livestock feed additives. These substances are rejected on the basis of their dependence on non-renewable resources, disruption potential within the environment, and their potential impacts on wildlife, livestock and human health. For example, synthetically compounded fertilizers and pesticides generally suppress biological activity in the soil. Some growth regulators and feed additives are implicated in retarding the decomposition of manure and are potential human health hazards. Instead, sustainable agriculture systems rely on crop rotations, crop residues, animal manures, legumes, green manures, off-farm organic wastes, appropriate mechanical cultivation, and mineral bearing rocks to maximize soil biological activity, and to maintain soil fertility and productivity. Natural, biological, and cultural controls are used to manage pests, weeds and diseases Introduction A sustainable agriculture is a system of agriculture that will last. It is an agriculture that maintains its productivity over the long run. Sustainable agriculture is both a philosophy and a system of farming. It has its roots in a set of values that reflects an awareness of both ecological and social realities. It involves design and management procedures that work with natural processes to conserve all resources, minimize waste and environmental damage, while maintaining or improving farm profitability. Working with natural soil processes is of particular importance. Sustainable agriculture systems are designed to take maximizes advantage of existing soil nutrient and Page | 37
water cycles, energy flows, and soil organisms for food production. As well, such systems aim to produce food that is nutritious, without being contaminated with products that might harm human health (McLeod P and Rashid, 2011). In simplest phrases, sustainable agriculture is the manufacturing of meals, fiber, or exceptional plant or animal merchandise using farming techniques that protect the environment, public health, human groups, and animal welfare. The phrase sustainable has grown to be very popular in recent years and it's far now used to explain loads of things (RoyBolduc and Hijri, 2011; Densilin DM, et al 2011). Food security is a pressing problem in India and in the world. According to the Food and Agriculture Organization of the UN (FAO), it is estimated that over 190 million people go hungry every day in the country. Evidence for India’s food challenge can be found in the fact that the yield per hectare of rice, one of India’s principal crops, is 2177 kgs per hectare, lagging behind countries such as China and Brazil that have yield rates of 4263 kgs/hectare and 3265 kgs/hectare respectively. The cereal yield per hectare in the country is also 2,981 kgs per hectare, lagging far behind countries such as China, Japan and the US. The slow growth of agricultural production in India can be attributed to an inefficient rural transport system, lack of awareness about the treatment of crops, limited access to modern farming technology and the shrinking agricultural land due to urbanization. Add to that, an irregular monsoon and the fact that 63% of agricultural land is dependent on rainfall further increase Sustainable agriculture techniques enable higher resource efficiency. They help produce greater agricultural output while using lesser land, water and energy, ensuring profitability for the farmer. These essentially include methods that, among other things, protect and enhance the crops and the soil, improve water absorption and use efficient seed treatments. While Indian farmers have traditionally followed these principles, new technology now makes them more effective. For example, for soil enhancement, certified biodegradable mulch films are now available. A mulch film is a layer of protective material applied to soil to conserve moisture and fertility. Most mulch films used in agriculture today are made of polyethylene (PE), which has the unwanted overhead of disposal. It is a labour intensive and timeconsuming process to remove the PE mulch film after usage. If not done, it affects soil quality and hence, crop yield. An independently certified biodegradable mulch film, on the other hand, is directly absorbed by the microorganisms in the soil. It conserves the soil properties, eliminates soil contamination, and saves the labor cost that comes with PE mulch films. The Page | 38
other perpetual challenge for India’s farms is the availability of water. Many food crops like rice and sugarcane have a high-water requirement. In a country like India, where majority of the agricultural land is rain-fed, low rainfall years can wreak havoc for crops and cause a slew of other problems - a surge in crop prices and a reduction in access to essential food items. Again, Indian farmers have long experience in water conservation that can now be enhanced through technology. Seeds can now be treated with enhancements that help them improve their root systems. This leads to more efficient water absorption. In addition to soil and water management, the third big factor, better seed treatment, can also significantly improve crop health and boost productivity. These solutions include application of fungicides and insecticides that protect the seed from unwanted fungi and parasites that can damage crops or hinder growth, and increase productivity. In addition to these, there are several general goals associated with sustainable agriculture, consisting of holding water, reducing the use of fertilizers and pesticides, and selling biodiversity in plants grown and the ecosystem. Sustainable agriculture additionally specializes in retaining monetary balance of farms and assisting farmers improve their techniques and satisfactory of existence (Tang, 2012). Ensuring Our Food Security Since the dawn of civilizations agriculture is one sector that impacts and in turn is impacted the most by environment. Hence sustainability of the human race and this world depends a lot on the environmental friendliness of our agriculture. India is facing a food crisis thanks to the systematic destruction of farmlands and food production systems over the last five decades through uncontrolled use of chemical fertilisers, pesticides, monocropping and other intensive agricultural practices. Instead of looking at the real problem the government is favouring false solutions like genetically engineered (GE) food crops. Ecological farming is the answer to the problems being faced by agriculture in our country today. It will also keep agriculture sustainable. This form of agriculture conserves our soil and water resources, protects our climate, enhances agro-diversity, ensures biodiversity, meets the demand for food and safeguards livelihoods. In short, it ensures that the environment thrives, the farm is productive, the farmer makes a net profit and society has enough nutritious food. India has a long history of agriculture. Over centuries, farmers in this country devised practices to keep our farms sustainable. Practices like mixed cropping, crop rotation, using organic manure and pest management kept our
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agriculture sustainable. But things changed for the worse with the onslaught of a chemical intensive model of agriculture, imposed through the so called Green Revolution in 1965. It was therefore not surprising when the International Assessment of Agricultural Science and Technology for Development [IAASTD], an initiative of the United Nations and World Bank, concluded that small-scale farmers and agro-ecological methods are the way forward if the current food crisis is to be solved. This initiative involved a three year review of all the agricultural technologies in the past 50 years by around 400 scientists across the world. The IAASTD said that to meet the needs of local communities, indigenous and local knowledge need to be declared as important as formal science. This is a significant departure from the destructive chemicaldependent, one-size-fits-all model of industrial agriculture. The report also acknowledges that genetically engineered crops are highly controversial and will not play a substantial role in addressing the key problems of climate change, biodiversity loss, hunger and poverty. Definitions of Sustainable Agriculture Sustainable agriculture is farming in sustainable ways based on an understanding of ecosystem services, the study of relationships between organisms and their environment. It has been defined as "an integrated system of plant and animal production practices having a site-specific application that will last over the long term", for example: 1.
Satisfy human food and fiber needs
2.
Enhance environmental quality and the natural resource base upon which the agricultural economy depends
3.
Make the most efficient use of non-renewable resources and on-farm resources and integrate, where appropriate, natural biological cycles and controls
4.
Sustain the economic viability of farm operations
5.
Enhance the quality of life for farmers and society as a whole
“A sustainable agriculture does not deplete soils or people." Sustainable agriculture is a form of agriculture aimed at meeting the needs of the present generation without endangering the resource base of the future generations. In order to feed the burgeoning population more food has to be produced and this has to be done without degradation of the resource base. Expanding agriculture to ecologically fragile areas means greater threat to environment. Sustainable agriculture is a balanced management system of renewable Page | 40
resources including soil, wildlife, forests, crops, fish, livestock, plant genetic resources and ecosystems without degradation and to provide food, livelihood for current and future generations maintaining or improving productivity and ecosystem services of these resources. Sustainable agriculture system has to be economically viable both in the short and long term perspectives. Natural resources- not only provide food, fiber, fuel and fodder but also perform ecosystem services such as detoxification of noxious chemicals within soils, purification of waters, favourable weather and regulation of hydrological process within watersheds. Sustainable agriculture has to prevent land degradation and soil erosion. It has to replenish nutrients and control weeds, pests and diseases through biological and cultural methods. Because agricultural systems are so diverse, based on farm size, location, crop being grown, socioeconomic background, among many other factors, and because the movement has become so widespread globally, sustainable agriculture has come to represent different things to different people. Nevertheless there are some common threads, concepts, and beliefs. In the most general terms, sustainable agriculture describes systems in which the farmer reaches the goal of producing adequate yields and good profits following production practices that minimize any negative short-and longterm side effects on the environment and the wellbeing of the community. The major goals of this approach are thus to develop economically viable agro-ecosystems and to enhance the quality of the environment, so that farmlands will remain productive indefinitely. Methods of Sustainable Agriculture Two of the various possible practices of sustainable agriculture are crop rotation and soil modification, every designed to make targeted that vegetation being cultivated can acquire the important vitamins and minerals for healthful expand. Soil amendments would encompass utilizing locally to be had compost from neighborhood recycling facilities. These neighborhood recycling facilities aid produce the compost wished by way of the regional organic farms.
Crop rotation: Crop rotation is likely one of the most effective procedures of sustainable agriculture. Its rationale is to maintain away from the consequences that include planting the equal plants throughout the equal soil for years in a row (Mahapatra et al 2014). It allows deal with pest troubles, a0073 many pests choose distinctive crops. If the pests have a consistent ingredients give they may be able to widely broaden their population dimension.
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Cover crops: Many farmers select to have crops planted in a discipline always and by no means depart it barren, this can purpose accidental results. By way of planting cowl plants, which include clover or oats, the farmer can achieve his desires of stopping soil erosion, suppressing the increase of weeds, and improving the great of the soil Using cowl vegetation also reduces the want for chemicals consisting of fertilizers.
Natural pest predators: So as to maintain powerful control over pests, it's far vital to view the farm as surroundings as opposed to a factory. Coping with your farm in order that it is able to harbor populations of these pest predators is an effective as well as a complicated method. The usage of chemical insecticides can result in the indiscriminate killing of pest predators (Chapman and Pratt, 1961).
Integrated pest management: This is an approach, which simply relies on organic instead of chemical techniques. IMP also emphasizes the importance of crop rotation to fight pest control. Once a pest problem is recognized, IPM will mean that chemical solutions will most effective be used as a closing resort. Alternatively the correct responses could be the use of sterile men, and bio control agents consisting of ladybirds
India – Policies for Sustainable Agriculture The Indian government’s policies have always emphasized food grain self-sufficiency, which has not necessarily coincided with agricultural sustainability. The growth of agricultural production and productivity, which had risen significantly during 1970s and 1980s, declined during 1990s. These slowdowns have worsened since 2000; both overall agricultural production and food grains production have shown negative growth rates in 2000-01 to 2002-03 periods (GoI, 2002). Decline in the growth rates of agricultural production and productivity is a serious issue considering the questions of food security, livelihood, and environment. As such, a critical examination of the approaches for sustainable agricultural development is necessary. This examination must be framed not only by India’s ongoing need to ensure food self-sufficiency but also by the consequences of access to international markets. Challenges Faced by Indian Agricultural Sector As mentioned earlier, several major challenges are facing Indian
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agricultural sector, and the primary stakeholders affected by these challenges include the i) agri-producers, ii) agricultural consumers, iii) the government and iv) the environment. Each of these stakeholders can influence the level of impact these challenges may have, for example the agricultural practices of producers can influence the level of food security. Similarly, governmental initiatives and policies play a vital role in providing food security. The First Key Aspect to Consider is That of Food Security Food security can be defined as i) the access to nutritionally adequate food at affordable prices, ii) is culturally accepted, and iii) can be accessed through non-emergency means at all times (Ramabulana 2011). According to a 2011 Food and Agricultural Organization of the United Nations (FAO) report, 839 million people in developing countries are undernourished. Climate Change The second key aspect to consider is that of climate change. Although globally producers have succeeded in providing in the growing supply of food products, conventional agricultural practices are held responsible for various environmental problems such as decelerating soil fertility and the decline in biodiversity (Reddy 2010; Singh and Grover). In the recent past, the costs of current food production practices to the environment and whether these practices are sustainable have been questioned (Gregory and George 2011). However, the non-financial benefits of adopting more environmentally friendly production methods, such as positive environmental outcomes and health benefits to consumers, cannot easily be expressed in monetary terms. Scientists from the Universities of Yale and Columbia in the USA, in collaboration with the World Economic Forum, issue a biennial report that measures 132 countries’ environmental performance indices (EPIs). These indicators indicate a country’s environmental health and ecosystem vitality. Biofuels The third aspect to consider is that of biofuel production. Biofuels have been simultaneously upheld as a method to reduce the impact of the use of fossil fuels and as a risk to food security due to it being a potential competitor for agricultural land used to grow crops for food consumption (Gregory and George 2011). Some Key Undesirable Side Effects of Modern Agriculture 1.
Unsustainable irrigation programs throughout the world are resulting in an undesirable buildup of salinity and toxic mineral levels in one out of five hectares under irrigation. Thus, agricultural water, a nonPage | 43
renewable resource whose use has tripled globally since 1950, has to be used more efficiently to minimize salinization problems. 2.
Excessive soil erosion, in the range of fifteen to forty tons per hectare annually, results in the loss of productive farmland in many parts of the world. Forested areas, a refuge for wildlife and biodiversity (biological diversity), are then often turned into agricultural fields to compensate for the loss of the abandoned eroded areas.
3.
The indiscriminate use of pesticides is affecting human health and wildlife populations, as first reported to the population at large in Rachel Carson's book Silent Spring (1962).
4.
The increased concentration of farms into larger and larger farm holdings is reducing the number of small family farms, believed by many to represent the heart of rural communities and to be key stewards of the environment.
5.
The trend toward larger farms and plantation-type monocultures is leading to a loss of global biodiversity. Biodiversity, many argue, may be a critical ecological feature that allows the continued survival of humans on earth.
Basic Elements of Sustainable Agriculture Sustainable agriculture’s benefit to farm and community economies is grounded in four well-established economic development principles and a fifth, concern for the community: Input Optimization: Sustainable production practices maximize onfarm resources. Internally derived inputs, such as family labor, intensive grazing systems, recycled nutrients, legume nitrogen, crop rotations, use of renewable solar energy, improved management of pests, soils and woodlands are a few examples of substituted resources. Studies have shown that these substitutions can be made while maintaining yields and often result in increased net farm earnings. These earnings can benefit the community by increasing local retail sales and providing a stronger tax base. Diversification: To develop healthy soils and reduce purchased inputs, sustainable agriculture emphasizes diverse cropping and livestock systems. Diversification can lead to more stable farm income by lowering economic risk from climate, pests, and fluctuating agriculture markets. This helps to keep farmers on the land and helps buffer the local economy from the shock of a dramatic decline in a single commodity/industry. Conservation of Natural Capital: It is standard accounting practice to Page | 44
depreciate capital assets. It has not been standard practice for farmers to depreciate natural capital that is depleted by farming methods that do not conserve resources. Nevertheless, the loss is real, eventually affecting yields, farm profitability, and sustainability. In sustainable agriculture, economic value is created by maintaining the productivity of land and water resources while enhancing human health and the environment. Capturing Value-Added: The marketing of crops and products grown is by far the weakest link in the farmers’ role in the ‘field to table’ food system. To create and maintain a truly sustainable agriculture, farmers will have to develop ways of retaining a higher percentage of value-added on the farm. While individuals farmers can and do design, process and direct-market their own products, many other value-added strategies require more resources than one farmer can handle financially. Therefore, these value-added strategies will require the formation of a coop of local farmers and a collaborative relationship with the local community. Community: The elements of sustainable agriculture are integral to all communities. If we are to support sustainable agriculture, we must recognize the rural/urban interconnection, the conflicts and tremendous opportunities. The positives of a sustainable farming system include shared commitment to profitability, food security, food safety, open space for water recharge, natural habitats for flora, fauna and recreation and a cooperative and supportive social and economic community infrastructure. Currently our urban communities are separated from farming communities not only in philosophy, but also in their mutual understanding, particularly in their knowledge of the entire food production and distribution system. Recognition of the role farming has played in stabilizing our community is critical or we shall continue to disintegrate our rural fabric and preferred standards of living. In other words, we must rekindle a sense of caring about the welfare of our neighbors in order for viable rural and urban communities to survive. Approaches of Sustainable Agriculture Many of the approaches in conventional agriculture (minimum tillage, chemical banding) would fall into the "efficiency" category. They demonstrate a reduction in resource use and associated negative environmental impact, and in many cases a reduction in input expenses for the farmer. They represent, however, only an initial step towards a truly sustainable system. Efforts to substitute safe products and practices (botanical pesticides, biocontrol agents, imported manures, rock powders and mechanical weed control) are also gaining popularity. Despite the reduced negative Page | 45
environmental damage associated with them, they remain problematic. Botanical pesticides also kill beneficial organisms, the release of bio-controls does not address the question of why pest outbreaks occur dependence on imported fertilizer materials makes the system vulnerable to supply disruptions and excessive cultivation to control weeds is detrimental to the soil. The systems that focus on redesign of the farm are the most sophisticated, generally the most environmentally and economically sustainable, over the long term. These farm systems recycle resources to the greatest extent possible, meaning that little is wasted, few pollutants are generated, and input costs are reduced substantially. For example, chicken and orchard operations have been successfully integrated. The manure is used as a fertilizer, the chickens eat pests that attack the fruit, the feed bill for the chickens is greatly reduced, and the eggs and/or meat can be consumed or sold. Three to seven year crop rotations can be designed that minimize tillage, use legumes and green manures to maintain soil fertility, prevent pest and disease outbreaks, and provide a diverse diet for livestock. Pigs and goats can be used to renovate wooded lands in preparation for sheep pasture. The pigs and goats replace the petrochemical energy that would be consumed in machines, herbicides and fertilizers. All these practices involve redesigning the farm. As in conventional agricultural systems, the success of sustainable approaches is very dependent on the skills and attitudes of the producers. The degree to which different models of such farms are sustainable is very variable, and is dependent on the physical resources of the farmer, and the degree deficiencies in support farm, the talents and commitment of the support available. The current from government, universities, and agricultural professionals means that farmers must often rely on their own talents and commitment. Plant Production Practices Sustainable production practices involve a variety of approaches. Specific strategies must take into account topography, soil characteristics, climate, pests, local availability of inputs and the individual grower's goals. Despite the site-specific and individual nature of sustainable agriculture, several general principles can be applied to help growers select appropriate management practices: Selection of Site, Species and Variety Preventive strategies, adopted early, can reduce inputs and help establish a sustainable production system. When possible, pest-resistant crops should be selected which are tolerant of existing soil or site conditions. When site Page | 46
selection is an option, factors such as soil type and depth, previous crop history, and location (e.g. climate, topography) should be taken into account before planting. Diversity Diversified farms are usually more economically and ecologically resilient. While monoculture farming has advantages in terms of efficiency and ease of management, the loss of the crop in any one year could put a farm out of business and/or seriously disrupt the stability of a community dependent on that crop. By growing a variety of crops, farmers spread economic risk and are less susceptible to the radical price fluctuations associated with changes in supply and demand. Properly managed, diversity can also buffer a farm in a biological sense. For example, in annual cropping systems, crop rotation can be used to suppress weeds, pathogens and insect pests. Also, cover crops can have stabilizing effects on the agroecosystem by holding soil and nutrients in place, conserving soil moisture with mowed or standing dead mulches, and by increasing the water infiltration rate and soil water holding capacity. Cover crops in orchards and vineyards can buffer the system against pest infestations by increasing beneficial arthropod populations and can therefore reduce the need for chemical inputs. Using a variety of cover crops is also important in order to protect against the failure of a particular species to grow and to attract and sustain a wide range of beneficial arthropods. Optimum diversity may be obtained by integrating both crops and livestock in the same farming operation. This was the common practice for centuries until the mid-1900s when technology, government policy and economics compelled farms to become more specialized. Mixed crop and livestock operations have several advantages. First, growing row crops only on more level land and pasture or forages on steeper slopes will reduce soil erosion. Second, pasture and forage crops in rotation enhance soil quality and reduce erosion; livestock manure, in turn, contributes to soil fertility. Third, livestock can buffer the negative impacts of low rainfall periods by consuming crop residue that in "plant only" systems would have been considered crop failures. Finally, feeding and marketing are flexible in animal production systems. This can help cushion farmers against trade and price fluctuations and, in conjunction with cropping operations, make more efficient use of farm labor. Soil Management A common philosophy among sustainable agriculture practitioners is that Page | 47
a "healthy" soil is a key component of sustainability; that is, a healthy soil will produce healthy crop plants that have optimum vigor and are less susceptible to pests. While many crops have key pests that attack even the healthiest of plants, proper soil, water and nutrient management can help prevent some pest problems brought on by crop stress or nutrient imbalance. Furthermore, crop management systems that impair soil quality often result in greater inputs of water, nutrients, pesticides, and/or energy for tillage to maintain yields. In sustainable systems, the soil is viewed as a fragile and living medium that must be protected and nurtured to ensure its long-term productivity and stability. Methods to protect and enhance the productivity of the soil include: 1.
Using cover crops, compost and/or manures
2.
Reducing tillage
3.
Avoiding traffic on wet soils
4.
Maintaining soil cover with plants and/or mulches
Efficient Use of Inputs Many inputs and practices used by conventional farmers are also used in sustainable agriculture. Sustainable farmers, however, maximize reliance on natural, renewable, and on-farm inputs. Equally important are the environmental, social, and economic impacts of a particular strategy. Converting to sustainable practices does not mean simple input substitution. Frequently, it substitutes enhanced management and scientific knowledge for conventional inputs, especially chemical inputs that harm the environment on farms and in rural communities. The goal is to develop efficient, biological systems which do not need high levels of material inputs. Growers frequently ask if synthetic chemicals are appropriate in a sustainable farming system. Sustainable approaches are those that are the least toxic and least energy intensive, and yet maintain productivity and profitability. Preventive strategies and other alternatives should be employed before using chemical inputs from any source. However, there may be situations where the use of synthetic chemicals would be more "sustainable" than a strictly nonchemical approach or an approach using toxic "organic" chemicals. For example, one grape grower switched from tillage to a few applications of a broad spectrum contact herbicide in the vine row. This approach may use less energy and may compact the soil less than numerous passes with a cultivator or mower. Consideration of Farmer Goals and Lifestyle Choices Management decisions should reflect not only environmental and broad social considerations, but also individual goals and lifestyle choices. For Page | 48
example, adoption of some technologies or practices that promise profitability may also require such intensive management that one's lifestyle actually deteriorates. Management decisions that promote sustainability, nourish the environment, the community and the individual. References 1.
Bengston M, et al. Chlorpyrifos-methyl plus bioresmethrin; Methacrifos; Pirimiphos-methyl plus bioresmethrin; and synergised bioresmethrin as grain protectants for wheat. Pesticide Sci. 1991; 11:61-76.
2.
Centre for Science and Environment (1999), The Citizen’s Fifth Report: Part II – Statistical Database, eds. Anil Agarwal, Sunita Narain and Srabani Sen, New Delhi.
3.
Chadha, G.K., Sen, S., and H.R. Sharma (2004), State of the Indian Farmer: A Millenium Study, Vol. 2: Land Resources, Ministry of Agriculture, Government of India, New Delhi, India.
4.
Chapman HD and Pratt FP. Methods of analysis for soil, plants and water. University of California, Division of Agriculture Science. 1961.
5.
Densilin DM, et al. Effect of Individual and Combined Application of Biofertilizers, Inorganic Fertilizer and Vermicompost on the Biochemical Constituents of Chilli (Ns - 1701). J Biofertil Biopestici. 2011:2:106.
6.
Government of India (2000), National Agriculture Policy – 2000, Ministry of Agriculture, New Delhi.
7.
Government of India (2001a), India: Nation Action Programme to Combat Desertification, Volume – I. Ministry of Environment and Forests, New Delhi.
8.
Government of India (2002), Tenth Five Year Plan 2002-2007, Volume – II, Planning Commission, New Delhi.
9.
Gregory PJ, George TS 2011. Feeding nine billion: The challenge to sustainable crop production. Journal of Experimental Botany, 62(15): 5233-5239.
10. Mahapatra BK, Sarkar UK, Lakra WS (2014) A Review on Status, Potentials, Threats and Challenges of the Fish Biodiversity of West Bengal. 11. Maiyappan S, et al. Isolation, Evaluation and Formulation of Selected Microbial Consortia for Sustainable Agriculture. J Biofertil Biopestici. 2010; 2:109.
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12. McLeod P and Rashid T. Laboratory Toxicity Profile of an Organic Formulation of Spinosad against the Eggplant Flea Beetle, Epitrix Fuscula Crotch. J Biofertil Biopestici. 2011; 2:103. 13. NRSA (2002), Wastelands Atlas of India, Department of Space, Hyderabad, India. 14. Ramabulana TR 2011. The rise of South African agribusiness: The good, the bad and the ugly. Agrekon, 50(2): 102-110. 15. Roy-Bolduc A and Hijri M. The Use of Mycorrhizae to Enhance Phosphorus Uptake: A Way Out the Phosphorus Crisis. J Biofertil Biopestici. 2011; 2:104. 16. Singh IP, Grover DK 2011. Economic viability of organic farming: An empirical experience of wheat cultivation in Punjab. Agricultural Economics Research Review, 24: 275-281. 17. Tang S. Developing and Analysing Pest-natural Enemy Systems with IPM Strategies. J Biofertil Biopestici. 2012; 3:101. 18. Vyas V. S. (2003), India’s Agrarian Structure, Economic Policies and Sustainable Development, Academic Foundation Publishers, New Delhi.
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Chapter - 4 Synthetic Seed: A Novel Technology Authors Divya Prakash Singh Assistant Professor, Department of Seed Science, BFIT, Sudhowala, Dehradun. Chandan Kumar Singh Research Associate, Department of Plant Pathology, Regional Plant Quarantine Station, Amritsar, Punjab Hadi Husain Khan Research Associate, Department of Entomoogy, Regional Plant Quarantine Station, Amritsar, Punjab
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Chapter - 4 Synthetic Seed: A Novel Technology
Introduction and Importnce: The synthetic seed technology has been developed to use somatic embryos and/or other micropropagules as seed analogues successfully in the field or greenhouse, and their mechanical planting at a commercial level (Bapat 2009). The discovery of tot potency of plant cells in 20th century and utilization of this concept in further years marked the beginning of a new era of plant biotechnology. Synthetic seed (Syn seed or artificial seed) is an emerging field with a vast potential for plant propagation, delivery and storage. Seeds in most of the crops are meant for propagation and storage because of ease in production and handling. However plants which are vegetativelypropagatedthere is problem of storage and handling. Basic aim of this technology is to convert different micropropagules, mainly somatic embryo into synthetic seeds which can be grown in the field or greenhouse when required. Production of seed occurs as an outcome of a sexual procedure; on that account, in cross-pollinating species the naturally produced seeds are genetically different to individual parent (Senaratna 1992). Nowadays, artificial seed technology is one of the most important tools to breeders and scientists of plant tissue culture. It has offered powerful advantages for large scale mass propagation of elite plant species. In general, synthetic seeds are defined as artificially encapsulated somatic embryos, shoot tips, axillary buds or any other meristematic tissue, used for sowing as a seeds and possess the ability to convert into whole plant under in vitro and in vivo conditions and keep its potential also after storage (Capuano et al., 1998). The somatic embryo can be encapsulated, handled and used like a natural seed was first suggested by Murashige (1977) and efforts to engineer them into synthetic seed have been ongoing ever since Kitto and Janick (1982),Gray (1987). Bapatet al., (1987) proposed the encapsulation of shoot tip in Morusindica; this application has made the concept of synthetic seed set free from its bonds to somatic embryos and broadens the technology to the Page | 53
encapsulation of various in vitro derived propagules. An implementation of artificial seed technology to somatic embryogenesis or the regeneration of embryos is based on the vegetative tissues as an efficient technique that allows for mass propagation in a large scale production of selected genotype (Araet al., 2000). The aim and scope for switching towards artificial seed technology was for the fact that the cost-effective mass propagation of elite plant genotypes will be promoted. There would also be a channel for new transgenic plants produced through biotechnological techniques to be transferred directly to the greenhouse or field.The artificial seed technology has been applied to a number of plant species belonging to angiosperms. Difference between Synthetic vs. Natural Seeds Synthetic seeds
Natural seeds
Produce from asexual process
Produce from sexual process
Do not involve the fusion of gametes
Involve the fusion of male and female gametes
Produce from the vegetative cells
Produce from the germ cells
Contains genetic constituents from single parents
Contains genetic constituents from both parents
No genetic recombination take palace
Genetic recombination take palace
Contains only embryo and endosperm and seed coat are absent
Contains embryo, endosperm and seed coat
Need for Synthetic Seeds? In some of the economically important crops, propagation through natural seed is not successful due to;
Heterozygosity of seeds particularly in cross pollinated crops
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Minute seed size eg; orchids
Presence of reduced endosperm
Some seeds require mycorrhizal fungi association for germination eg: orchids
When no seeds are formed…
Where in-vivo propagation techniques are time & space consuming e.g. propagation of certain horticultural crops.
Elimination of parental lines in hybrid seed production i.e. elimination of costly process of hybrid seed production.
Maintenance of self-incompatible or male sterile lines
Cryo-preservation of artificial seeds can be done for germplasm conservation of recalcitrant spp.
Artificial seeds are free of pathogens thus, the transportation of pathogen free propagules across the international borders can be done easily avoiding bulk transportation of plants, quarantine and spread of diseases.
A number of useful materials such as nutrients, fungicides, pesticides, antibiotics and microorganisms (eg. rhizobia) may be incorporated into the encapsulation matrix.
A Brief History of Synthetic Seed •
Steward et al. (1958) – Reported on somatic embryogenesis in plants
•
Murashige (1977) – First idea of synthetic seeds and proposed that somatic embryos can be encapsulated, handled and used like a natural seed for transport, storage and sowing.
•
Kitto and Janik (1982) – First report on synthetic seeds in carrot
•
Molleet al. (1982). Produced artificial seeds of carrot.
•
Redenet al. (1984).developed a technique for encapsulation of individual SE of alfalfa.
•
Redenbaughet al. (1984)-developed a technique for hydrogel encapsulation (Calcium alginate as coating agent) of individual somatic embryos of alfalfa.
•
Bapat and Rao (1989 ) – Synthetic seeds in Sandal wood and Mulberry
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•
McKersie (1989 )- Synthetic seeds in hybrid Alfalfa
•
Onishiet al.(1994) – Automation
Principle Synthetic seed contains an embryo produced by somatic embryogenesis enclosed with in an artificial medium that supplies nutrients and is encased in an artificial seed covering. As a result somatic embryos are identical genotype. What is Somatic Embryo?
Somatic embryo are bipolar structures with both apical and basal meristematic regions, which are capable of forming shoot and root respectively.
SEs have been used for micro-propagation of several plant spp and in some spp they are the only route available for the purpose e.g. oil palm and date palm.
Procedure of Somatic Embryogenesis:
(Kumar 2012)
Petiole explants plants are surface sterilized and cultured on SH medium (Schenk and Hildebrandt, 1972) containing 2,4-D, kinetin and many other nutrients. 2,4-D activates the cell cycle of many cells in the petiole - those in the vascular cambium develop into a callus, whereas some sub-epidermal cells develop into a somatic embryo. Page | 56
The initial somatic embryos, which are only small dense cell clusters at this stage, are embedded in a callus mass of non-differentiated cells.
To liberate these proembryonic structures, and to stimulate the formation of more embryos, the callus is dispersed in a liquid medium to form a suspension culture containing 2,4-D but not kinetin
After 7 days, the suspension is sieved and transferred to solid medium lacking 2, 4-D On this medium the embryos develop through morphological stages that appear to be globular, heart and torpedo.
Maturation Phase I: Once the majority of embryos reach the torpedo stage (7-10 days after sieving) they are transferred to an enriched medium containing a high level of sucrose, nitrogen and sulphur to prevent precocious germination and to enable deposition of storage reserves. The embryos rapidly accumulate fresh and dry weight, reaching 1-2 mg dry weight per embryo. Maturation Phase II: To induce the acquisition of desiccation tolerance, the somatic embryos are placed on a modified medium containing abscisic acid (ABA) for 3 days. Then they are removed from the medium, washed to remove sugar and other nutrients, and dried. The standard method of drying is to place the somatic embryos in a sealed chamber over a saturated salt solution designed to give specific relative humidifies. Daily for one week, the embryos are transferred to a progressively lower relative humidity chamber and finally are dried at ambient conditions. At this stage, the embryos have reached approximately 15% moisture and can be stored for a year or more with good viability.
Different Stage of Embryo Development Initiation Somatic Embryogenesis Requires - Auxins, cytokinins and low sucrose content - Specific explants
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Types of Somatic Embryogenesis 1) Direct Embryogenesis It refers to the development of an embryo directly from the original explant tissue without an intervening callus phase. 2) Indirect Embryogenesis It is the formation of embryos from callus or cell suspension or from cells or group of cells or of cell or somatic embryos is known as indirect embryogenesis. Steps of Direct Somatic Embryogenesis
Steps of Indirect Somatic Embryogenesis
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Some Examples of Synthetic Seeds In vitro propugales for encapsulation
Crop
Somatic embryos
Papaya, Brinjal, Mango, Carrot, Capsicum, Cauliflower, Broccoli, Celery
Axiliary buds/ adventitious buds
Grape, Citrus, Pineapple
Shoot tip
Banana, Apple, Kiwifruit
Production of Synthetic Seeds
Synthetic seeds: It is living seed-like structure derived from somatic embryoidsIn vitro culture after encapsulation by a hydrogel.
Such seed are encapsulated by protective gel like calcium alginate against microbes and desiccation.
Steps of Synthetic Seed Production
How are Synthetic Seed Made?
Shoot buds cut from shoot cultures can be used for synthetic seed production. They are cut to 2-3mm in size and placed in the encapsulation matrix (Sodium alginate).
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Those cultured plant parts allowed to form Somatic embryos which are ideal for synthetic seed production.
Using a sterile 10 ml pipette, the shoot bud or somatic embryo is drawn up with some encapsulation matrix.
•
The shoot bud or somatic embryo is dropped into the complexation solution (Calcium nitrate) and a capsule is formed and allowed to harden.
•
Capsule hardness can be controlled by the concentration of the complexation solution and the complexation time.
•
Size of the capsule is determined by the size of the shoot bud or somatic embryo and the inner diameter of the pipette used.
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•
The capsules or synthetic seeds are collected by decanting off the complexation solution and rinsed in water.
•
The synthetic seeds should be pliable enough to cushion and protect the embryo, yet allow germination and growth of the shoot bud or somatic embryo.
•
It should be rigid enough to withstand rough handling during manufacture, transportation and planting.
•
For the artificial seeds to remain dormant until planting, a thin layer of water-soluble resin is used to coat the encapsulation matrix.
Encapsulation Procedures of encapsulation were firstly hypothesized in 1978 by Murashige who assumed their possible use to protect somatic embryos regenerated by in vitro culture during manipulation in laboratories. He provided the first definition of synthetic seed or artificial seed as “an encapsulated single somatic embryo”. Procedure of Encapsulation
Coating Three–four millimeters-longexplants, excised from in vitro or in vivo plant material are singly dipped into a gelling orencapsulating solution for a few seconds. For this purpose, sodium alginate is the mostfrequently used due to its moderate viscosity, low spin ability of solution, no toxicity to theexplants, low cost and biocompatibility. Moreover, sodium alginate is Page | 61
employedbecause it provides better protection to the encapsulated explants against mechanicaldamages, depending on its concentration (usually ranging from 2 to 5% w/v), level ofviscosity or commercial type, and from the complexation conditions. Many othersubstances were essayed as coating agents, in substitution to sodium alginate, like sodiumalginate with gelatin, potassium alginate, polyco 2133, carboxymethyl cellulose,carrageenan, gelrite, guargum, sodium pectate, tragacanth gum (Falcinelliet al,. 1993), (Redenbaughet al., 1993 ) and (Saiprasad., 2001) Complexation In order to give hardness to involucres, the alginate-coated explants are dropped into a calcium chloride solution (1.0- 1.5% w/v) for 20–40 min. Ionexchange takes place during this time, obtaining the replacement of Na+ by Ca++ forming calcium alginate (Redenbaugh and Walker 1990). When the monovalent ion of sodium is replaced by divalent ions of calcium, ionic crosslinking among the carboxylic acid groups occurs, and the polysaccharide molecules form a polymeric structure called “egg-box” (Barbotinet al., 1993) Thus, the coating acquires the necessary consistence to assure protection against mechanical damages and dehydration risks. Hardening of calcium alginate bead is affected by the concentration of sodium alginate and calcium chloride and it may vary also in relation to the complexation time. Usually, higher texture corresponds to good protection during transport and manipulation, but higher difficulty to break the coating by the explant, after sowing. Rinsing Washing the hardened involucres of explants in distilled water is required several times in order to remove the toxic residual ions of chloride and sodium. After washing, encapsulated explants can be stored before transferring on sowing substrate to inducevegetative activity in the enclosed plantmaterial. The encapsulated procedure shows efficiencywhen the enclosed explants maintain viability (i.e., green colour, with no necrosis oryellowing appearance along the period betweenencapsulation and use), regrowth ability (i.e., growth of explants with consequent breakage ofthe involucre and extrusion of at least one smallshoot or root after sowing). Usually, to achievethese conditions, nutrients and/or growthregulators were added besides the rinsing waterin the solutions employed for coating andcomplexation. The composition of the nutritivesolution is similar to that employed for the invitro shoot proliferation of themicropropagation, but usually with allcomponents at half concentration. This solutionis currently called artificial endosperm andmimics the role of the seed endosperm becauseit provides nutritive support to the Page | 62
encapsulatedexplant, especially during its storage andregrowth, following the sowing (Carlson and Hartle 1995) and (Gardi 1999) Materials Needed for Encapsulation Gel (concentration) (% w/v)
Complex Agents Consternation (µM)
Sodium alginate (0.5-5.0) Sodium alginate with gelatin (2.0-5.0) Carragenan (0.2-0.8) Locust bean gum (0.4–1.0)
Calcium salt (100-300) Calcium Chloride (30-100) Potassium Chloride Ammonium Chloride (500)
Methods of Encapsulation A. Dropping Procedure
The most useful encapsulation system. Drip 2-3 % sodium alginate drops from at the tip of the funnel and the somatic embryos are inserted.
Keep the encapsulated embryos complex in calcium salt for 20 min.
Rinsed the capsules in water and then stored in an air tight container.
B. Automate Encapsulation Process This is the quick method of synthetic seed production. a)
Blank alginate capsules were planted in speeding trays using a vacuum seeder. b) The blank capsules are planted in the field using a stanhay planter. c) A hydrophobic coating is required for mechanical handling.
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Types of synthetic seeds A. Desiccated Synthetic Seed B. Hydrated Synthetic Seed A. Desiccated Synthetic Seed
Seeds are produced from somatic embryos either naked or encapsulated in poly-oxy-ethylene glycol (Polyoxy) followed by their desiccation.
Desiccation can be achieved either slowly over a period of one or two weeks sequentially using chambers of decreasing relative humidity, or rapidly by unsealing the petri dishes and leaving them on the bench overnight to dry.
SEs may also be hardened by treating them with ABA during their maturation phase
Such types of synthetic seeds are produced only in plant species whose somatic embryos are desiccation tolerant.
Kim &Janicle (1982) 1st developed desiccated synthetic seeds from SE of carrot. (5% solution of polyethylene oxide)
B. Hydrated Synthetic Seed
Seeds are produced by encapsulating the somatic embryos in hydrogels like sodium alginate, potassium alginate, or sodium alginate with gelatine etc.
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Encapsulation or synthetic seed or artificial seed are used to provide protection to the artificially produced propagules.
Redenberghet al., (1986) develop hydrated synthetic seeds by mixing SE of alfalfa, celery & cauliflower with sodium alginate followed by dropping into a solution of calcium chloride/nitrate to form calciumalginate.
Desirable Attributes of Synthetic Seed Coat •
Non damaging to the somatic embryo
•
Durable during storage, transportation and planting
•
Protect the embryo while allowing for germination and conversion
•
Contain nutrients, micro-organism necessary for germination
•
Enable the formation of mono-embryogenic synthetic seed
Storage of Synthetic Seeds: •
In general synthetic seeds can be stored for 6 months at 4 oC
•
Dried alfalfa somatic embryo can be stored at room temperature with 40 – 50% RH for one year (Seneratnaet al., 1990)
•
No decline in survival of carrot somatic embryos for eight months under 45% RH. (Rai, 1992)
•
Incorporation of ABA in maturation medium enhanced the storability in sugarcane (Ravi and Anand2012)
Potential Uses of Synthetic Seeds
Reduced cost of transplanting
Carrier of adjuvant such as microorganism, plant growth regulators, pesticides, fungicides, nutrients antibiotics
Large scale monoculture
Can be conceivably handled as seed using conventional planting equipment
Analytical tools
Production of large no of identical embryos
Determination of role of endosperm in embryo development germination
Study of somaclonal variation
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Limitations: •
High end technology involved in synthetic seed production
•
Asynchrous development of somatic embryos
•
Improper maturation of somatic embryos that makes them inefficient for germination and conversion in to normal plants
•
Lack of dormancy and stress tolerance in somatic embryos that limit the storage of synthetic seeds
•
Somaclonal variations which may alter the genetic constituent of the embryos
Future Challenges The concept of direct manipulation of the embryo through somatic embryogenesis and production of synthetic seed from the somatic embryo offers immense potential for the production of superior performing seed of a number of crops. However, numerous technical hurdles associated with have to be improved. Conclusion •
Standardization of methods for synchronization of developing propagules followed by automation of whole process like sorting, harvesting, encapsulation and germination of the coated propagules can enhance pace in production of synthetic seeds.
•
This technology can be a great aid to conventional methods for supplying adequate quantity and quality propagules towards food security.
•
Synthetic seed technology is yet to be commercialized for large scale applicability.
•
Appropriate policy initiatives must be under taken for further research and commercialization of synthetic seeds.
References 1.
Ara H, Jaiswal U, Jaiswal VS (2000). Synthetic seed: prospects and limitations. Current Science 78:1438-1444.
2.
Bapat VA, Mahatre M, Rao PS. (1987). Propagation of Morusindica L. (Mulbery) by encapsulated shoot buds. Plant Cell Rep. 6:393-395.
3.
Bapat VA. (2009). Synthetic seeds: A novel concept in seedbiotechnology. Nuclear Agriculture and Biotechnology Division. Page | 66
4.
Barbotin, JN., Nava Saucedo, JE., Bazinet, C., Kersulec, A., Thomasset, B., Thomas, D. (1993). Immobilization of whole cells and somatic embryos: coating process and cell-matrix interaction. Synseeds: Applications of Synthetic Seeds to Crop Improvement. CRC Press Inc, Boca Raton, California.
5.
Capuano C, Piccioni E, Standardi A. (1998). Effect of different treatments on the conversion of M.26 apple rootstock synthetic seeds obtained from encapsulated apical and axillary micropropagated buds. Journal of Horticulture Science 73:299-305.
6.
Carlson, WC., Hartle, JE.(1995). Manufactured seeds of woody plants. Somatic Embryogenesis in Woody Plants, Vol. 1: History, molecular and biochemical aspects and applications. Kluwer Academic Publishers, Dordrecht.
7.
Falcinelli, M., Piccioni, E., Standardi, A. Ssemesinteticonellepianteagrarie: problemie prospettive. SementiElette, 2: 3-13.
8.
Gardi, T., Piccioni, E., Standardi, A. (1999). Effect of bead nutrient composition on regrowth ability ofstored vitro-derived encapsulated microcuttings of different woody species. Journal of Microencapsulation, 16(1): 13-25.
9.
Gray DJ. (1987). Synthetic seed technology for the mass cloning of crop plants: problems and prospects. Horticulture Science22:795-814.
(1993).
10. Kitto SK, Janick J. (1982). Polyox as an artificial seed coat for asexual embryos.Horticulture Science 17: 488-490. 11. Kumar U. (2012).Synthetic seeds production.Agrobios (India) pp-5-6.
for
commercial
crop
12. Murashige T. (1977). Plant cell and organ culture as horticultural practice.Acta Horticulture 78:17-30. 13. Rai MK, Asthana P, Singh SK, Jaiswal VS, Jaiswal U. (1992). The encapsulation technology in fruit plants—a review. Biotechnology Advance 27:671–679. 14. Ravi D and Anand P. (2012). Production of artificial seeds: A review. International Research Journal of Biological Sciences. Vol. 1 (5), 74-78. 15. Redenbaugh, K., Fujii, JAA., Slade, D. (1993). Hydrated coatings for synthetic seeds.Synseeds: Applications of Synthetic Seeds to Crop Improvement. CRC Press Inc., Boca Raton, California. Page | 67
16. Redenbaugh, K., Walker, K. (1990). Role of artificial seeds in alfalfa breeding. Plant Tissue culture: applications and limitations. Development in Crop Science. Elsevier, Amsterdam. 17. Saiprasad, GVS. (2001). Artificial seeds and their applications. Resonance, 6(5): 39-47. 18. Senaratna T. (1992).Artificial seeds. Biotechnology Advance 10:379–392
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Chapter - 5 Enhancing Nutrient use Efficiency through Next Generation Fertilizers in Vegetable & Field Crops Authors R.K.Naresh Department of Agronomy Mukesh Kumar Department of Horticulture S.P.Singh K.V.K.Baghpat Ashish Dwivedi Department of Agronomy Robin Kumar Indian Institute of Farming System Research, Modipuram, Meerut-250110, U.P., India
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Chapter - 5 Enhancing Nutrient use Efficiency through Next Generation Fertilizers in Vegetable & Field Crops
Invariably, many agricultural soils of the world are deficient in one or more of the essential nutrients needed to support healthy plants. Acidity, alkalinity, salinity, anthropogenic processes, nature of farming, and erosion can lead to soil degradation. Additions of fertilizers and/or amendments are essential for a proper nutrient supply and maximum yields. Estimates of overall efficiency of applied fertilizer have been reported to be about or lower than 50% for N, less than 10% for P, and about 40% for K. Plants that are efficient in absorption and utilization of nutrients greatly enhance the efficiency of applied fertilizers, reducing cost of inputs, and preventing losses of nutrients to ecosystems. Inter- and intra-specific variation for plant growth and mineral nutrient use efficiency (NUE) are known to be under genetic and physiological control and are modified by plant interactions with environmental variables. There is need for breeding programs to focus on developing cultivars with high NUE. Identification of traits such as nutrient absorption, transport, utilization, and mobilization in plant cultivars should greatly enhance fertilizer use efficiency. The development of new cultivars with higher NUE, coupled with best management practices (BMPs) will contribute to sustainable agricultural systems that protect and promote soil, water and air quality. The changes in climate that are predicted to occur during the next century present many challenges to sustainable crop production and food security. A burgeoning world population accompanied by increasing standards of living will require unprecedented levels of production of food, fiber, and industrial crops. This needs to be achieved with little further increase in the area of arable land and with finite and increasingly expensive supplies of fertilizer. Greater productivity needs to occur at a time when large areas of the world’s agricultural land will experience increases in the frequency and severity of heat stress and drought (Handmer et al. 2012). Improvements are also needed in the nutrient content of the major stable food crops to alleviate the chronic nutritional problems that occur in many countries, but particularly in developing countries (Graham et al., 2007). These challenges have brought
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the importance of plant nutrition to sustainable agricultural production into sharp focus and have highlighted the need to improve nutrient use efficiency (NTUE). The higher yields that will be required to maintain (or improve) food security will require increased uptake of most of the essential nutrients at a time when shortages of some fertilizers are being predicted (Cordell et al. 2009). Most agricultural soils are deficient in one or more essential nutrients or have other nutritional constraints to yield. The substantial increases in global grain production that have occurred up to now have been based, in part, on improvements in crop nutrition. However, successes of the past are no guarantee for future improvements. It is acknowledged that the yield improvement that was associated with using increasingly high rates of fertilizer has led to rates of nutrient input in excess of crop requirements, leading to low NTUE, a waste of input of nutrients, and reductions in soil and water quality in many regions of the world (Vitousek et al. 2009). On the other hand, there are still regions of the world where chronically low soil fertility is limiting agricultural production. Improvements in NTUE will rely on identifying weaknesses in current production practices and correcting past failures, as well as developing novel approaches to improve nutrient supply and nutrient efficiency. Despite the central role of plant nutrition in sustaining the productivity of agricultural systems, the effect of climate change on nutrient availability and uptake has received little consideration. Attention has focused on breeding for tolerance to heat and drought resistance and only brief mention is made about crop nutrition, and then comments are confined largely to nitrogen nutrition (Olesen et al., 2011). Balanced nutrition of crops is not only important in its own right, but maintaining an adequate level of crop nutrition is also important to help plants cope with biotic and abiotic stress (Cakmak and Kirkby 2008). Consequently, the productivity and resilience of crop production in the face of changes in climate will be linked to the ability to maintain the nutritional health of crops and to enhance the NTUE of the cropping system. There are two approaches to improving NTUE: using crop management to improve the supply and efficiency of nutrient uptake and its conversion to a harvestable product, and improving the ability of crop plants to take up and use nutrients from the soil and fertilizer. The two approaches are complementary and substantial gains in the NTUE of a farming system are likely to come when both strategies are used. We have witnessed the effect of combining variety improvement with fertilizer use in the past when high yielding varieties of crops allowed higher rates of fertilizer (and other inputs) to be applied, leading to large increases in productivity; ich also resulted in an increase in NTUE (Ortiz-Monasterio et al. 1997). The effects of climate change on productivity will be variable and will be influenced by the ability Page | 72
of farmers to adapt to a changing environment. This will be affected not only by their financial resources, and access to information and technology but also their perception of risk and the foibles of human decision making (Hayman et al. 2011). Growing a new variety with superior traits is frequently a low-risk investment and farmers readily adopt new varieties if they perceive a benefit in doing so. Modern high-yielding varieties have been widely adopted in developing countries because they have increased yields and yield stability (Renkow and Byerlee 2010). Genetic improvement in NTUE has the potential to make an important contribution to overcoming the challenges of climate change, improving productivity and 10 Nutrient Use Efficiency 335 moderating the adverse effects of climate change on the sustainability of agricultural systems. It may be especially important in developing countries where poverty and lack of infrastructure limit the options of farmers to respond to climate change and who, as a consequence, are the most vulnerable to climate change. The cause for low NUE and declining response to N fertilizers can be grouped as follows (NAAS 2005) Nutrient Supply and Soil Fertility
Susceptibility of N fertilizers to losses by various mechanisms.
Imbalanced use fertilizers.
Poor management for secondary and micronutrients, especially S, Zn, Mn, Fe and B.
Use of high analysis fertilizers like urea and diammonium phosphate (DAP) and inadequate addition of organic manures.
Inappropriate rate, time and method of application.
Low status of soil organic carbon and soil degradation due to high salinity, sodicity, acidity, water-logging and having adverse effect on below-ground biodiversity, especially of agriculturally-important micro-organisms.
Agronomic Practices
Delayed sowings/plantings.
Low seed rate resulting in poor crop stands.
Poor weed management.
Inefficient irrigation and rainwater management.
Large scale monoculture and non-inclusion of legumes in cropping Page | 73
systems.
Lack of consideration of previous cropping in the same field.
Lack of capturing water x nitrogen synergistic interaction.
Inadequate plant protection.
Non-availability of seeds of HYVs at affordable price and at the appropriate time.
Lack of more efficient N using genotypes. The suggested approaches to minimize N losses and increase use efficiency include the following option (Roy and Pederson 1992):
Identification of the most suitable fertilizer material.
Manipulation of the application techniques including split application and placement.
Manipulation of particle size, use of coating materials and other chemicals.
Judicious and economical application of fertilizers for synergistic interactions.
Application of organic sources along with mineral fertilizers.
Efficient agronomic management practices such as tillage, irrigation, mulching, weed control, plant population and use of varieties with higher NUE.
Efficient input use can be achieved by assessment of available inputs and conservation against possible losses, integrated use of inputs in a synergistic manner, optimal allocation of inputs among the competing demands to achieve maximum return, maximizing input use efficiency by developing suitable site specific technologies. Efficient Nutrient Management Nutrient plays a key role in increasing agricultural production through intensive cropping. Sustainable agriculture can be achieved by efficient utilization of this costly input. Nutrient use efficiency can be improved by checking the path ways of nutrient losses from soil-plant system, making integrated se of nutrients from all possible sources, optimal allocation of nutrients to cops and maximizing the utilization of applied and native nutrients by the crops.
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Checking the Pathways of Nutrient Losses Nutrient present in soil and added through fertilizers and manures are lost by gaseous loss, leaching loss, runoff/erosion losses and fixation in soil. Efficient nutrient management demands understanding the pathways of nutrient losses and developing technologies to minimize these losses. Reducing Gaseous Loss Part of the applied N is lost from soil by volatilization of ammonia and part of the nitrogen is lost as N2O and N2 gas by denitrification. Volatilization loss of ammonia can be minimized by mixing of nitrogen fertilizers in soil rather than broadcasting on soil surface, deep placement of urea super granules (USG) in puddle rice field, using urease inhibitors like thiourea, methyl urea, caprylohydroxamic acid, phenyl phosphorodiamidate (PPD), ammonium thiosulphate etc. and adding inorganic salts of Ca, Mg or K with urea. Some coated material like sulphur coated urea (SCU), gypsum coated urea (GCU), plastic coated urea (PCU), mud ball urea and synthetic slow release urea based fertilizers viz., isobutylidene diurea (IBDU) and crotobylidene diurea (CDU) etc. may be used to retard the rate of urea hydrolysis and thereby, reducing ammonia volatilization. Nitrous oxide (N2O) is mainly produced by denitrification of NO 3-under anaerobic condition, as in lowland rice fields. Nitrous oxide is one of the greenhouse gases that are believed to be forcing global climate change. Dentrification loss can be minimized by avoiding the use of NO 3— form of nitrogenous fertilizer (e.g. calcium ammonium nitrate, potassium nitrate etc.) in rice and use of nitrification inhibitors viz., Dicyandiamide (DCD), N-serve (2-Chloro, 6-Chloro methyl pyridine), AM (2-Amino, 4-Chloro, 6-methyl pyrimidine), coated calcium carbide (CCC), neem coated urea, deep placement of urea sugar granules (USG) in flooded rice field and efficient and efficient water management. Reducing Leaching Loss Mobile nutrients (e.g. NO3--) are lost from the soil-plant system with the percolating water. Besides reducing the nutrient may pollute the groundwater. The groundwater having more than 10 mg NO3--, N per litre is unfit for drinking purpose (WHO). Leaching loss of NO3— can be minimized by balanced fertilization, split application of urea synchronizing with crop demand, manipulation of water application and rooting depth, appropriate crop rotations and use of slow release fertilizers and nitrification inhibitors like N-serve, DCD, AM, CCC and neem-coated urea. Despite the success of synthetic nitrification and unrease inhibitors in research farms they have poor Page | 75
acceptability among farmers because of high cost. However, the use of products plants like neem for coating urea can be popularized among the farmers to affect N economy and minimize long-term environmental consequences of denitrification and nitrate leaching. Reducing Runoff and Erosion Losses Many water-soluble nutrients are lost through runoff. This loss can be minimized by proper crops land management and selection of proper crops and cropping systems, tillage and mulching. Nutrients sorbed on the surface of soil particles-clays and silt and soil organic matter are lost when the top soil is eroded by water or wind. Proper soil conservation measures should be adopted to minimize this loss. Reducing Fixation of Nutrients in Soil In acid soils phosphorus is fixed as Fe++ and Al++ phosphates and in neutral and calcareous soils it gets fixed as Ca++ phosphate. The availability of these fixed phosphates is very low. Phosphate-fixation in acid soil can be reduced by combined application of rock phosphate and single super phosphate and liming of acid soils. In both acid and calcareous soils phosphorus fixation can be minimized by band placement of phosphatic fertilizers along with crop rows. Use of rock phosphate along with acid forming materials like pyrites or phosphate-solubilizing microorganisms help in solubilizing of sparingly soluble rocks. Vesicular-arbuscular mycorrhizal (VAM) fungi are helpful in mobilizing both applied and native P reserves. K ++ and NH4++ ions are also fixed in the interlayer of 2:1 clay minerals like illite, vermiculite etc. nutrients fixed on soil-plant system but are not available to the crop in a short term period. However, these are released at later stages of crop growth. Optimizing Nutrient Use Efficiency The fertilizer industry supports applying nutrients at the right rate, right time, and in the right place as a best management practice (BMP) for achieving optimum nutrient efficiency. Site Specific Nitrogen Management (SSNM) SSNM is a concept which involves field specific N management strategies that includes quantitative knowledge of field specific variability in crop N requirement and expected soil N supplying power. The fundamental underlying assumption of this concept is to establish an optimum synchronization between supply and demand of N for plant growth. On the basis of when and what type of decisions are made, SSNM can be grouped in Page | 76
two categories, (1) prescriptive SSNM, (2) corrective SSNM. In former approach of N management, the amount and its application time are analyzed prior to sowing based on N supplying power of the soil, expected crop N requirement for assumed yield target, expected N efficiency of fertilizer products in use. Contrast to this, corrective nitrogen management strategy involves use of diagnostic tools to assess nitrogen status of standing crop. The interpretation of these recorded data is serving as the basis for decisions about timing and quantity of N applications (Schroeder et al., 2000). Chlorophyll meters (SPAD), nutrient expert and leaf color charts (LCC) are the promising and gaining importance in recent years for corrective N management in cereals. Site-Specific Nutrient Management (SSNM) aims to optimize the supply of soil nutrients over time and space to match the requirements of crops through four key principles (Table 1). The principles, called the “4 Rs”. Table 1: Examples of key scientific principles and associated practices of 4R nutrient stewardship SSNM principle
Scientific basis
Product
Ensure balanced supply of nutrients Suit soil properties
Rate Time Place
Assess nutrient supply from all sources Assess plant demand Assess dynamics of crop uptake and soil supply Determine timing of loss risk Recognize crop rooting patterns Manage spatial variability
Associated practices Commercial fertilizer, Livestock manure Compost, Crop residue Test soil for nutrients, Balance crop removal Apply nutrients: Pre-planting, At planting, At flowering, At fruiting Broadcast, Band/drill/inject Variable-rate application
Right Rate Crops require a certain amount of plant nutrients for production of profitable crops. Part of this nutrient quantity can be supplied from the soil, and the remainder must come from fertilizer, either synthetic sources or organic forms (such as livestock wastes composts) or green manure crops. The first key to practicing the right rate concept is soil testing. Before the crop is planted and any fertilizer has been applied, soil testing can help determine the portion of the crop nutrient requirement that is already available from the soil. Using a strong research information base, the recommendation for the right rate of fertilizer can be made from the soil test result. Most crops are location and season specific depending on cultivar, management practices, climate, etc., and so it is critical that realistic yield goals are established and that nutrients are applied to meet the target yield. Page | 77
Over- or under-application will result in reduced nutrient use efficiency or losses in yield and crop quality. Soil testing remains one of the most powerful tools available for determining the nutrient supplying capacity of the soil, but to be useful for making appropriate fertilizer recommendations, good calibration data is also necessary. Unfortunately, soil testing is not available in all regions of the world because reliable laboratories using methodology appropriate to local soils and crops are inaccessible or calibration data relevant to current cropping systems and yields are lacking. Other techniques, such as omission plots, are proving useful in determining the amount of fertilizer required for attaining a yield target (Witt and Dobermann 2002). In this method, N, P, and K are applied at sufficiently high rates to ensure that yield is not limited by an insufficient supply of the added nutrients. Target yield can be determined from plots with unlimited NPK. One nutrient is omitted from the plots to determine a nutrient-limited yield. For example, an N omission plot receives no N, but sufficient P and K fertilizer to ensure that those nutrients are not limiting yield. The difference in grain yield between a fully fertilized plot and an N omission plot is the deficit between the crop demand for N and indigenous supply of N, which must be met by fertilizers. Nutrients removed in crops are also an important consideration. Unless nutrients removed in harvested grain and crop residues are replaced, soil fertility will be depleted. The right rate refers to the amount of fertilizer needed for the crop production season and is based on extensive research over locations, crops, varieties, and years. The right rate also refers to the amount of fertilizer applied at one time in the growing season. For example, the farmer needs to know, depending on the cropping system used, the right rate of fertilizer to apply in the following scenarios: In the pre plant application, while the mulched bed is made for plasticulture vegetables
As a starter fertilizer for direct-seeded crops like maize, or cotton
As the amount to inject (fertigation) into the drip irrigation system at any one time
In a single side-dressing during the growing season for an unmatched crop
In a single fertigation through the center-pivot irrigation system
Sometimes the right rate to apply at any one time is related to the nutrient involved. For example, in plasticulture crops, all of the phosphorus may be Page | 78
applied to the soil while the bed is made. Likewise, a portion of the nitrogen and potassium may be applied while the bed is being made and the remainder applied through the drip irrigation system. Right Time The right timing of nutrients takes into consideration the growth pattern of the crop and, therefore, natural changes in nutrient demand during the season. Crop development begins slowing from seed germination or transplanting, then increases through fruiting, and finally slows down at maturation. This pattern for crop development is referred to as sigmoidal growth. Anticipating changes in growth and nutrient demand is important so that fertilizer application can be timed to meet the needs of growth. The right timing is often interrelated with the right rate and right placement. For example, as the drip-irrigated tomato crop develops, the rate changes with time so that smaller rates are applied later in the growing season. Greater rates of nutrients are applied at or just before the time when the vegetative growth rate is maximal and fruits are being developed. Rainfall is difficult to predict; however, when possible, fertilizer application should be timed to minimize the chance of leaching of nutrients due to heavy rainfall. Right Place: For maximum nutrient efficiency, nutrients need to be placed where the plant will have the best access to the nutrients. For most crops, the right placement is in the root zone or just ahead of the advancing root system. Most nutrient uptake occurs through the root system, so placing the nutrients in the root zone maximizes the likelihood of absorption by the plant. Banding and broadcasting are two general approaches to nutrient placement. Banding is the placement of fertilizer in concentrated streams or bands in the soil, typically near the developing plant. Broadcasting is the spreading of fertilizer uniformly over the surface of the soil. Whether to use banding or broadcasting often depends on the type of crop and the development or spread of the root system. Broadcasting is usually most effective either later in the season when roots of a row-crop have explored the space between the rows, or for forage crops that cover the entire soil surface. Fertigation of nitrogen through a center-pivot irrigation system for corn may be a type of fertilizer broadcasting system. Placement and timing interact because as the crop develops, the root system expands. Placement of fertilizer ahead of the advancing root system Page | 79
for unmatched crops, like potato or cotton, avoids damage to the root system by the fertilizer application equipment. Another example of this interaction would be for fertigation with a pivot irrigation system. The first side-dressings of nitrogen early in the growth cycle for corn may be applied by knifing liquid fertilizer to the side of the row, followed later in the season with applications through the irrigation system. These combinations of timing and placement maximize the likelihood of nitrogen uptake by the plant related to the expansion of the root system. The tillage system may affect the placement of nutrients. For example, incorporating a nutrient may not be possible in certain minimum tillage systems. In no-till corn production, early nitrogen and phosphorus applications can be made by banding near the seeds with the planter, with later applications of nitrogen by the center-pivot irrigation system. The right placement is also related to the nutrient in question. For example, phosphorus can become fixed in unavailable forms when it is mixed in with some soils. The main reason P is banded is that it is immobile in the soils and therefore has to be placed nearer to the roots (or the roots have to grow towards the P granule). In sandy loams, P applied to the surface will get adsorbed and can accumulate over time. Accumulations also occur in soils applied with P sourced from organic or manure related amendments. In these situations, banding of the fertilizer reduces, at least temporarily, the mixing of the fertilizer with the soil and increases the chance that phosphorus will remain in a soluble form for root uptake. For example, banding starter-phosphorus may be preferable to broadcasting. The right placement may also relate to the form of the nutrient source, such as urea nitrogen. Nitrogen from urea may be subject to loss by volatilization when the urea is left on the surface of soil with a high pH. Incorporating the urea or applying a small amount of irrigation to move the urea into the soil helps reduce volatilization losses. In certain situations and for certain nutrients, foliar applications of fertilizer may be preferred. For example, micronutrients may be more efficiently applied to the foliage for iron or manganese when the soil pH is high. Right Source Selecting the right source of fertilizer or the right material to deliver the nutrients is important. The right source can be related to the following questions:
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What source of nutrient(s) would be the least expensive per unit of delivered nutrient?
Should an organic source (compost or manure) of nutrient be considered?
When is a controlled-release fertilizer the right source?
What sources can simultaneously deliver more than one needed nutrient?
When should a liquid form be used instead of a dry form?
When should the salt index of the fertilizer be considered in selecting the right source?
The right source often involves the ease of application of a nutrient and cost per unit of nutrient. In addition, efficiency of nutrient use may be considered. For example, a controlled-release nitrogen source may be preferred to deliver small amounts of nutrients throughout the growing season, instead of larger amounts of nitrogen delivered in a few side-dressings from a soluble source. The right source may be manure if the farmer would like to take advantage of the organic matter supplied along with the plant nutrients. The organic matter may increase the water-holding capacity and nutrient supply of the soil. Best management practices ensure effective use of fertilizers in improving the efficiency of all inputs used in cropping systems. The goal of their use is to apply the most appropriate sources at the right rate, time, and place. Opportunities abound for improving nutrient use efficiency effectively:
Genetics and management practices assuring maximum economic yields.
Enhanced-efficiency fertilizer products using controlled-release technologies.
Precision agriculture technologies to sense crop needs and improve application.
Increased use of on-farm measures evaluating nutrient use efficiency.
Decision support tools applying science at the farm level.
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SPAD Chlorophyll Meter Chlorophyll meters have proven useful in fine-tuning in-season N management. The SPAD-502 chlorophyll meter is a simple, portable, diagnostic and nondestructive light weight device used to estimate leaf chlorophyll content (Minolta, 1989). Chlorophyll meter techniques provide a substantial saving in time and resources and offer a new strategy for synchronizing nitrogen (N) application with actual crop demand. The chlorophyll meter readings have been positively correlated with destructive chlorophyll measurements in many crop species and considered as a useful indicator of the need of N top-dressing during the crop growth. Nitrogen is one of the major nutritional elements that limit crop yields. Farmers in many parts of the world likely to apply this element in excess amount for achieving high yield. Excessive N application decreased grain yield and increased N loss in a wheat-soil system. Therefore, plant need-based N fertilizer use is crucial for high N use efficiency. However, determining the optimal fertilizer dose is one of the most difficult tasks. Many studied suggests that a positive correlation between N uptake, leaf N concentration, leaf chlorophyll content, and grain yield (Guendouz et al., 2014; Goncalves da Silva et al., 2011). These relationships also suggest that N management could be made effectively by measuring leaf relative chlorophyll content. It is interesting that leaf chlorophyll content or leaf greenness may provide a better estimate of potential yield than leaf N concentration. In this regard the SPAD chlorophyll meter can be used as an alternative to nitrogen nutrition index (NNI) to measure N status in field crops. Therefore, SPAD values have been successfully used for N fertilizer management in rice, wheat and maize. Grain Yield and Flag Leaf SPAD Value Relationship The flag leaf SPAD reading showed positive strong correlations with grain yield (Table 2). Combatively higher values of correlation coefficient (r) Page | 82
were maintained in flag leaves from 67 to 97 DAS. The 'r' value decreased to some extent starting from 99 DAS indicating that SPAD values of flag leaves up to 96 DAS is important for yield prediction in wheat. Swain and Sandip (2010) also observed a significant and positive correlation between flag leaf N content and SPAD value (R2=0.80) and SPAD value at different growth stages and grain yield of rice. Table 2: Relationship between flag leaf SPAD values with grain yield in wheat Stage of crops and corresponding SPAD reading (DAS)
Coefficient of co-relation (r) with grain yield (g/plants)
67
0.928**
71
0.991**
74
0.982**
77
0.997**
80
0.983**
83
0.985**
87
0.975**
90
0.983**
93
0.987**
96
0.984 **
99
0.891**
102
0.852**
**indicate significance at 1% level. Multiple Regression Equation We formulate the following multiple regression models for grain yield and SPAD values at different growth stages of wheat: (i) Y1= -2.13+0.102x1 (r2=0.58) (ii) Y1= -1.92+0.001x1+0.100x2 (r2=0.96) (iii) Y1= -2.33+0.012x1+0.011x2+0.085x3 (r2=0.97) (iv) Y1= -2.18+0.021x1+0.099x2+0.142x3-0.152 x4 (r2=0.98) (v) Y1= -3.47+0.001x1+0.318x2+0.140x3-0.541x4+0.238x5 (r2=0.98) (vi) Y1=-2.90-0.029x1-0.088x2+0.016x3+0.003x4-0.008x5+0.218x6 (r2=1.00) (vii) Y1=-2.90-0.029x1-0.085x2+0.016x3-0.006x5+0.216x6+0.001x7 (r2=1.00) where, y1= wheat grain yield (g/plants) and x1, x2, x3, x4, x5, x6 and x7 are Page | 83
the SPAD readings at 45, 50, 55, 60, 65, 70 and 75 DAS, respectively. From the multiple regression models, it is clear that there are strong significant effects of SPAD values at 50 DAS and continued to 75 DAS corresponding to the vegetative and reproductive stages of crop. This implies that maintaining of leaf chlorophyll content during this period is very important for higher grain yield. In this period appropriate management of soil fertility would be necessary for sustainable wheat yield. This model provides a good fit in the chi-square test. Leaf Color Charts (LCC) LCC is a diagnostic tool which can help farmers for making appropriate decisions regarding the need for nitrogen fertilizer applications in standing crops. Conventionally farmers use eye observations to know the crop nutrient status particularly nitrogen. The LCC can act as a plant health indicator diagnostic tool particularly to optimize the nitrogen supply of rice based cropping systems. The LCC is economical and easy to use diagnostic tool for precise N management especially in rice-wheat cropping system. Conceptually it is based on the measurement of relative greenness of plant leaves which directly co-related with its chlorophyll content. Nitrogen is a principle component of leaf chlorophyll so its measurement over various phenological stages serves as the indirect basis for nitrogen management. Green Seeker To reduce the amount of wasted reactive nitrogen (N) reaching the environment and to achieve high N fertilizer use efficiency, a site-specific N management strategy using Green Seeker™ optical sensor (GS) was evaluated in dry direct-seeded rice (DDSR) in the north western India. Green Seeker TM optical sensor (GS) is emerging as a tool for site-specific need based N fertilizer management in cereals. It uses normalized difference vegetation index (NDVI) based on reflectance of radiation in the red and near-infrared bands. Application of a prescriptive dose of N in two or three equal split doses, followed by a corrective N dose guided by GS at panicle initiation stage resulted in an increase in rice yield levels comparable to that obtained by following general recommendation at lower total N fertilizer application. N use efficiency was also improved by more than 12% when N fertilizer management was guided by GS as compared to when general N fertilizer recommendation was followed. Precision Farming Precision farming is an information and technology based farm input Page | 84
management system which aims at the use of technologies and principles to identify, analyse and manage spatial and temporal variability associated with all aspects of agricultural production within fields for maximum profitability, sustainability, enhancing crop performance, protecting land resources and maintain or improve the environment quality (McBratney et al., 2003) Measurement of variability in the field with respect to N and application of right amount of N at right time by the use of variable rate applicator, remote sensing, geographic information systems (GIS) and global positioning systems (GPS) technology may act as important information tools for the farmers to improve NUE under specific conditions of each field. Remote or local N sensors can be used in sophisticated management approaches to assess crop needs for supplemental N (Schmidt et al., 2002). These practices include the timely and precise application of N fertilizer to meet plant needs varying across the landscape. Geographical Information System (GIS) Geographic information system is a technology for handling available data regarding to geographic features of the crop field. It is an organized assembly which consist of collection of geographic data by using computer hardware and software on the one hand and precisely store, retrieve, analyze and display all form of geographically referenced information according to use. GIS can display analyze information in the form of maps that allow not only better understanding of interactions among yield, soil fertility, insectpest, weed flora and other factors and processes that control crop yield but also provide an opportunity for decision making based on spatial variability. Global Positioning Systems (GPS) Global Positioning Systems (GPS) is a common tool to collect spot data for agricultural, urban, and natural resources including soil, water bodies and crops. This is satellite based information system, which accurately determines the location of object anywhere on Earth. GPS system enables farmers for judicial use of inputs such as fertilizers, sprayers, and tillage operation to reduce excess uses. They can also be used to precisely apply crop inputs based on variable rate and frequently use in soil sampling, draw weed map, disease and insect infestations in fields with yield monitors and record crop yields in fields. Nutrient Expert Based N Management Proper nutrient management in exhaustive maize and wheat based systems should aim to supply adequate fertilizers based on the demand of the component crops and apply in ways that minimize loss and maximize the use Page | 85
efficiency (Basso et al., 2011). In this regard nutrient expert is an emerging N management diagnostic tool wherein the input variables such as fertilizers are applied in the right amount, at the right place and at right time (variable rate application) as per demand of the crop-plants (Pampolino et al., 2012). It helps to improve the input use efficiency, economy of fertilizer use and ensures sustainable use of natural resources. The steps involved in smart N management using nutrient expert are as follows A) ensuring an optimal density of crops, B) Evaluate ongoing nitrogen management practices, C) establishment of meaningful yield goal, D) determine quantum of indigenous soil N, E) Required N fertilizer rates for above selected yield goal, F)Translate fertilizer N rates into fertilizer sources, G) Develop an efficient application strategy for N fertilizers, H) compare the expected or actual benefit of ongoing and improved N management practices (Majumdar et al., 2013). Emerging and Established Technologies to Increase Nitrogen Use Efficiency Classic Fertilizer Sources Organic fertilizers were the most popular N sources in the past. Their N content ranges between 1% and 3% and, as a consequence of their low N content, these sources must be applied at high rates (several tons per hectare). Manufactured fertilizers became important sources of N only in the last century. From 1860 to the early 1990s, anthropogenic N production globally increased from 15 to 156 TgNyr−1 (Galloway et al., 2004). Among inorganic fertilizers, anhydrous ammonia contains the highest concentration of N (>80%, which constitutes the major advantage of using this source. In addition, it has a low cost in several countries. As it is a gas and must be pressurized for storage and handled as a liquid, it requires specialized equipment for storage, handling, and application. In addition, the effect on soil pH produced by this source might require lime to maintain a desired soil p H. This later effect is not exclusively from anhydrous ammonia but from all ammoniacal sources. Aqua ammonia (ammonium hydroxide) is composed of 25% to 29% of NH3 by weight. Transportation limits aqua NH3 production to small, local, and fluid fertilizer plants and since ammonia volatilizes quickly at temperatures above 10 °C, it is usually injected into soil depths of 50 to 100 mm or applied on the surface and incorporated immediately with temperatures over 10 °C. Ammonium nitrate (NH4NO3), from an agronomic point of view, is an excellent fertilizer because it combines two different N forms. It was reported that it allows improving the baking quality of wheat. However, its low N Page | 86
content compared to other sources makes the transportation, storage, and application more expensive per unit of N. Ammonium sulfate ((NH4)2SO4) is a source of both N and S that can be advantageous for acid-requiring crops (e.g., rice) and in high-pH soils (while it is undesirable in acidic soils). The main disadvantage of ammonium sulfate is its relatively low N content (21% N) compared to other sources. However, ammonium sulfate is popular in many parts of the world, particularly in some rice-producing areas. Monoammonium (NH4H2PO4) and diammonium ((NH4)2HPO4) phosphates are more important P sources than N sources due to their relative low N concentration. The advantage of these globally popular fertilizers resides in their dual nutrient composition. Ammonium chloride (NH 4Cl) is a low N source highly used for rice in Japan, China, India, and Southeast Asia. Ammonium chloride is a suitable N source for chloride (Cl−) responsive crops (e.g., cereals or coconut). Ammonium chloride, like ammonium sulfate, is undesirable in acid soils because it increases acidity and its use is limited to chloride-tolerant crops. Ammonium bicarbonate (NH4HCO3) is a source with low N content (19% N) that has been used almost exclusively in China. Urea (CO (NH2)2) is the most widely used N source worldwid. Favorable characteristics of manufacturing, costs, handling, storage, and transport make urea a very competitive N source. Some of the disadvantages of urea are that its use is associated to significant ammonia volatilization losses and it contains biuret, which is a phytotoxic compound that affects sensitive crops (e.g., citrus, and pineapple). Free NH3 released from urea hydrolysis also has toxic effects on germinating seedlings during the emergence stage. Ureaammonium nitrate solutions (UAN) are produced from urea and ammonium nitrate and are also popular N solution fertilizers. One of the major drawbacks of UAN solutions is the tendency to salt-out during cold weather. Nitrate salts such as sodium nitrate (NaNO3), potassium nitrate (KNO3), and calcium nitrate (Ca (NO3)2) are additional N sources available as fertilizers. Sodium nitrate, NaNO3 (16% N), was in the past a major source of N in Chile, while KNO3 (13% N) is common in horticultural crops such as tomatoes, potatoes, tobacco, leaf vegetables, citrus fruits, peaches, and other crops. Calcium nitrate (Ca (NO3)2, 15% N, 19% Ca) is a common fertilizer for winter vegetable production and for foliar sprays for celery, tomatoes, and apples. Controlled and Slow N Release Fertilizers Controlled-release and slow N release fertilizers that minimize losses through volatilization and leaching were identified as promising tools to
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mitigate the negative effects of nitrous oxide (N2O) and methane emissions (CH4) on global climate and also sources that increase the recovery of applied N fertilizer. These fertilizers release soluble N (NH4 and/or NO3) over several weeks or months and they increase the amount of fertilizer recovered by improving the synchronization between N availability and crop demand. Most products involve nitrification and urease inhibition and/or low water solubility compounds that undergo chemical and/or microbial decomposition to release N. However, the precise rate of release cannot be controlled. In such sense, some authors have distinguished controlled-release from slow-release fertilizers because they release nutrients by physical processes such as diffusion. Slow N release fertilizers, in contrast, are those that release nutrients by chemical or biochemical processes (e.g., aldehydes). The main disadvantage of slow release fertilizers is the cost, which can be four to eight times the cost of conventional fertilizers (e.g., urea).Therefore, they are primarily used in turfgrass, landscaping, ornamental, vegetable crops, greenhouse crops, and in transplantation of coniferous seedlings. Urease inhibitors have been commercially used in some countries with some degree of success. Shoji et al. (2001) showed in a field experiment that the use of a controlled release fertilizer (dicyandiamide and polyolefin coated urea) instead of conventional N sources (UAN and ammonium polyphosphate) increased potato tuber yields and N use efficiency by 17% and 58%, respectively. Additionally, Delgado and Mosier, (1996) reported that ureadicyadiamide (DCD) significantly reduced the emissions of N2O and N losses to the environment. The principal purpose of using nitrification inhibitors is to keep the N fertilizer in the NH4 form for a longer period. Nitrification inhibitors also may reduce denitrification N losses by decreasing the amount of NO3− available for denitrification. Although nitrification inhibitors were originally developed to minimize N losses, they have also been proposed as a mean of altering the predominant form of N in the soil. Coarse textured soils with low soil organic matter are generally the most responsive to nitrification inhibitors. However, the management of nitrification inhibitors is complex because it is difficult to predict when and how much N will be lost, while conditions favorable for NO3− leaching may develop after the inhibitor has degraded. In addition, a consistent yield increase from the use of nitrification inhibitors was not always observed (Abalos et al., 2014). Sulfur-coated urea has the greatest suitability where multiple applications of N during the growing season are needed, particularly on sandy soils under high rainfall or irrigation. It is advantageous to be used on sugarcane, pineapple, grass forages, turf, and ornamentals, fruits such as cranberries and strawberries, and rice under intermittent or delayed flooding. Urea and organic compounds that Page | 88
inhibit the microbial activity and hydrolysis of urea rely on microbial decomposition as the primary mechanism of N releases (Havlin et al., 2004). Urea-triazone is a controlled-release N compound predominantly used for foliar applications that exhibits excellent absorption properties with no toxicity to plants. Polymer-coated fertilizers (PCFs), on the other hand, are the most advanced products in controlling N release and improving nutrient efficiency. Because most polymer-coated products release by diffusion through a semipermeable membrane, the rate of release can be altered by composition of the coating and the coating thickness. For example, it is possible to alter the rate in which polymer-coated urea release N in time intervals that spanned from 20 to 90 days (Shoji et al., 2001). Due to the relatively high cost of these products, their use has been restricted mostly to high-value products. Microorganisms Used for Crop N Nutrition Several microorganisms are currently used in agriculture, and many others show potential to be used in the future. There are indications that microbial inoculants could be integrated into fertilization programs and could potentially reduce nutrient inputs (Bindraban et al., 2015). There are, however, still doubts about the beneficial effect, effectiveness, negative interactions and potential risks, especially concerning the stability of the inoculants over time and under varying climatic conditions. Microorganisms of the genus Rhizobium sp. are currently used worldwide, since they fix N2 in symbiosis with leguminous crops. The inoculation of soybean with the optimal species/strain has a significant impact on the yield and quality (Collino et al., 2015). A positive response to inoculation depends on limited N availability and that the inoculant bacteria are present in a higher concentration and has greater capacity to compete than native populations. Interactions between Rhizobium sp. and vesiculararbuscular mycorrhizas (VAM) in the rhizosphere of leguminous crops were reported to increase N uptake due to an increased availability of P and higher C translocation to the N fixing nodules. Several experiments in different environments suggest that Azospirillum sp. inoculation may increase yield of certain cereals (García et al., 2012). Azospirillum sp. have been proven to fix effectively N2, however the beneficial effects of inoculation have been mainly attributed to increased root development and thus to increased rates of water and mineral uptake. A slight yield increase of the inoculated plants over the control suggests that these inoculations combined with an integrated management strategy, might be Page | 89
suitable for low input systems. The group of rhizospheric microorganisms known as plant growth– promoting bacteria (PGPB) includes bacterial genres as Azospirillum, Azotobacter, Pseudomonas, Acetobacter, Serratia, Bacillus, and Burkholderia. PGPB have shown potential to promote vegetative growth when they are used to inoculate row or horticultural crops. These microorganisms can have direct effects on plants like the production of growth regulators that are absorbed by the plant and stimulate the uptake of nutrients. The indirect effects that PGPB has on plants are attributed to the prevention of the plant’s being colonized by phytopathogens. Field grown wheat inoculated with three species of Bacillus sp. consistently increased wheat grain quality and the use efficiency of the applied fertilizer. Several reports show positive effects on growth and nodulation of leguminous crops when they were co-inoculated with Rhizobium sp. and PGPB. One explanation for the contrasting results is that the expected grain yield increases by PGPBs are usually below 5%, a threshold not easy to detect with conventionally designed field experiments. There are, however, commercial inoculants available for beans, lentils, and wheat that contain the fungus Penicillium bilaii, which increase the uptake of nutrients (Leggett et al., 2015). The use of those inoculants that are effective will help to develop novel management strategies for sustainable agriculture (Vacheron et al., 2013). The potential of phyllospheric microorganisms to enhance N nutrition is still not clear. Nevertheless, certain phyllospheric microorganisms could play a role in plant nutrition; e.g., the cyanobacteria Scytonema javanicum and Scytonema hofmanni have shown the capacity to influence the ability of legumes to fix N and to uptake NH3 on leaf surfaces. With advances in molecular and biochemical techniques, the research on how management practices impact soil activity has been expanded and developments increasing NUE are to be expected. New Potential N Sources Biomethanation is used as a technique to produce biofuel from biomass. Fermented residues left after biomethanation processes can be used for liquid fertilizer production and as raw materials for compost. The use of fertilizers derived from biomethanation has expanded in the last years. In Germany, for example, more than 4000 farm anaerobic bioreactors produce 390,000 t of N (Moller and Müller, 2012). This N is suitable for cereals and vegetables and is usually applied as liquid fertilizer (Nkoa, 2014). Nan-ofertilizers (1–100 nm), on the other hand, are highly reactive due to Page | 90
their small size and large surface area, compared to bulk materials. As a consequence, the positive effects of nanofertilizers on crop growth may occur at lower doses than with the same nutrient supplied in its bulk from. Although research on how they can be exploited in specific crops is incipient, recent results and patent requests suggest potential useful benefits (Gogos et al., 2012). Concerning N, it is possible to hypothesize that as N sources that are highly soluble in water, N nanofertilizers once applied would be transformed in highly dynamic forms and that this characteristic would make N nanofertilizers particularly suitable to correct rapidly severe N deficiencies. Recent research suggests that their nano-dimensions allow their uptake through stomatal openings and the base of trichomes (Subramanian et al., 2015). As with most new technologies, nanotechnology involves certain risks since it could have undesirable effects on non-target organisms such as plants and plant or soil microbes; thus, research for the development of nanofertilizers should be accompanied with studies addressing the environmental consequences of its use. What Is Nano Fertilizer? Nano-fertilizers “Nano fertilizers are synthesized or modified form of traditional fertilizers, fertilizers bulk materials or extracted from different vegetative or reproductive parts of the plant by different chemical, physical, mechanical or biological methods with the help of nanotechnology used to improve soil fertility, productivity and quality of agricultural produces. Nanoparticles can make from fully bulk materials [9]. At nano scale physical and chemical properties are differ than bulk material. Rock phosphate if use as nano form it may increase availability of phosphorus to the plant because direct application of rock phosphate nanoparticles on the crop may prevent fixation in the soil similarly there is no silicic acid, iron and calcium for fixation of the phosphorus hence it increase phosphorus availability to the crop plants [11]. Important Properties of Nano Fertilizers which Facilitate Higher Nutrient Use Efficiency The nano-fertilizers have higher surface area it is mainly due to very less size of particles which provide more site to facilitate different metabolic process in the plant system result production of more photosynthets. Due to higher surface area and very less size they have high reactivity with other compound. They have high solubility in different solvent such as water. Particles size of nano-fertilizers is less than 100 nm which facilitates more penetration of nano particles in to the plant from applied surface such as soil Page | 91
or leaves. Nano fertilizer have large surface area and particle size less than the pore size of root and leaves of the plant which can increase penetration into the plant from applied surface and improve uptake and nutrient use efficiency of the nano-fertilizer. Reduction of particle size results in increased specific surface area and number of particles per unit area of a fertilizer that provide more opportunity to contact of nano-fertilizers which leads to more penetration and uptake of the nutrient. Fertilizers encapsulated in nano-particles will increase availability and uptake of nutrient to the crop plants. Zeolite based nano-fertilizers are capable to release nutrient slowly to the crop plant which increase availability of nutrient to the crop though out the growth period which prevent loss of nutrient from denitrification, volatilization, leaching and fixation in the soil especially NO3-N and NH4-N. Particle size below 100 nm nano-particles can use as fertilizer for efficient nutrient management which are more eco-friendly and reduce environment pollution.Main reason for high interest in fertilizers is mainly their penetration capacity, size and very higher surface area which is usually differ from the same material found in bulk form. This is partially due to the fact that nano particles show a very high surface: volume ratio. Thus, the reactive surface area is proportionally over-represented in nano particles compared to larger particles. Particle surface area increases with decreasing particle size and the surface free energy of the particle is a function of its size. Achievements of Nano-Fertilizers Nano fertilizers providing greater role in crop production and several research study revealed that nano fertilizers enhanced growth, yield and quality parameters of the crop which result better yield and quality food product for human and animal consumption. This translates into an improvement to three major areas of production. Yields Several research studies revealed that application of nano-fertilizers significantly increase crop yield over control or without application of nanofertilzer it is mainly because of increasing growth of plant parts and metabolic process such as photosynthesis leads to higher photosynthets accumulation and translocation to the economic parts of the plant. Foliar application of nano particles as fertilizer significantly increases in yield of the crop. Nutritional Value Nano fertilizers provide more surface area and more availability of nutrient to the crop plant which help to increase these quality parameters of Page | 92
the plant (such as protein, oil content, and sugar content) by enhancing the rate of reaction or synthesis process in the plant system. Application of zinc and iron on the plant increase total carbohydrate, starch, IAA, chlorophyll and protein content in the grain. Nano-Fe2O3 increase photosynthesis and growth of the peanut plant. Health Some nutrient also responsible disease resistance to the plant and due to the more availability of nano nutrient to the plant it prevent from disease, nutrient deficiency and other biotic and abiotic stress which indicate that nano fertilizers enhance overall health of the plant. ZnO nano-particles also helpful to plant under stress conditions. Aqueous solutions of Ag+ and Au+ drastically reduced the body weight of P. ricini larvae. Advantages of Nano Fertilizers over Traditional Fertilizers Nano fertilizers are advantageous over conventional fertilizers as they increase soil fertility yield and quality parameters of the crop, they are nontoxic and less harmful to environment and humans, they minimize cost and maximize profit. Nano particles increase nutrients use efficiency and minimizing the costs of environment protection. Improvement in the nutritional content of crops and the quality of the taste. Optimum use of iron and increase protein content in the grain of the wheat (Farajzadeh et al., 2009). Enhance plants growth by resisting diseases and improving stability of the plants by anti-bending and deeper rooting of crops. [8] Also suggested that balanced fertilization to the crop plant may be achieved through nanotechnology. Effects of Nano-Fertilizers on Seeds Germination & Growth Parameters of the Plant Nano fertilizers can easily penetrate into the seed and increase availability of nutrient to the growing seedling which result healthy and more shoot length and root length but if concentration is more than the optimum it may show inhibitory effects on the germination and seedling growth of the plant. Nano particles have both positive and negative effects on the plant. Nano ZnO recorded higher peanut seeds germination percent and root growth compare to bulk zinc sulphate (Prasad et al., 2012). Similarly positive effective of nanoscale SiO2 and TiO2 on germination was reported in soybean (Liu et al., 2005). Reported higher seed germination, shoot length, root length under nano fertilizers treatment over control or without nano fertilizer treated seeds. Nano fertilizers increase availability of nutrient to the growing plant which increase chlorophyll formation, photosynthesis rate, dry matter production and result Page | 93
improve overall growth of the plant (Mahajan et al., 2013). There is evidence that certain nutrients might be required to facilitate seed germination, especially those needed for early-required amino acids. This suggests that coating seeds with nutrients could be a promising technique to improve N nutrition. Seeds can be coated with nutrients to allow better early contact between the emerging radical and nutrients released from the coating formulation. Seed coating with N alone demonstrated greater efficacy than N combined with P. However, coating with P enhanced P uptake by the plant. Yield & Yield Parameters Nano fertilizers enhance the seed germination, vigor, growth parameters (plant height, leaf area, leaf area index number of leaves per plant) dry matter production, chlorophyll production, rate of the photosynthesis which result more production and translocation of photosynthets to different parts of the plant. Nano-TiO2 treated seed produced plant recorded more dry weight, higher photosynthetic rate, chlorophyll-a formation compared to the control. This improve translocation of photosynthets from source (leaves) to sink (economic part of the plant it may be grain, tuber, bulb, stem, fibre and leaves.) which result in more yield and quality parameters from nano-fetilizers treated plants compare to without nano fertilizers treated plants or traditional fertilizers treated plants. After nutrients are used by crops and consumed by humans, animals, or through industrial processes to produce energy or any other good, the waste ends up in the environment. Recapturing of nutrients either directly lost from the field or after consumption by humans and animals should become a more integral part of fertilizer production. Recycling these nutrients reduces overall losses and helps to recapture nutrients for plant uptake. Optimal Allocation of Nutrients The available nutrients should be optimally allocated among the competing crops to get the maximum returns by following optimizing of nutrient production functions which relate crop responses to applied nutrients under given soil, climate and management factors. Fertilizer allocation to crops based on soil test crop correlation approach for targeted yield can help in improving the nutrient use efficient by crops. Enhancing Recovery of Added Nutrients by Crops The nutrient management practices that help in enhancing nutrient recovery by crops, maximizing yield and minimizing losses of nutrient lead to enhanced nutrient use efficiency. Some of these practices include selection of crops and cropping systems, balanced nutrition application and selection of Page | 94
proper, rate, time and method of nutrient application, optimum interaction with other inputs and amelioration of problem soils. Selection of Crops and Cropping Systems Proper genotype of a crop should be selected which can mine the nutrients from soil and applied sources and converts them into desired output. Crops and cropping systems should be selected such that the residual nutrient left by one crop is efficiently utilized by the crops. Balanced Fertilization Major factor responsible for the low and declining crop response to fertilizers is the continuous mining of soil without adequate replenishment to a desired extent (NAAS, 35). The continuous use of N fertilizers alone or with inadequate P and K application has led to mining of native soil P and K. it is estimated that about 28 million tons of NPK are removed annually by crops in India, while only 18 million tones or even less are added as fertilizer, leaving a net negative balance of 10 million tones. Further, soil are getting continuously depleted of S and micronutrients like Zn, B, Fe and Mn due to continued adoption of intensive cropping systems and use of high analysis fertilizers without adequate addition of organics. Balanced fertilizer use at the macro level in India is generally equated with a nutrient consumption ration of 4:2:1 (N: P 2O5:K2O). The N: P2O5:K2O ratio is as wide as 30.8:8.8:1 in Punjab, 48.2, 14.9:1 in Haryana and 53.0:19.3:1 in Rajasthan compared with all India average of 6.9:2.6:1 (FAI.2004-05). Balanced fertilizer i.e., use of fertilizer nutrients in right proportion and in adequate amount are considers as promising agro-techniques to sustain yield, increase fertilizer use efficiency and to restore soil health. Continuous heavy application of only one nutrient disturbs the nutrient balance and leads to depletion of other nutrients as well as to under-utilization of fertilizer N. the response of a crop to N not only depends on the status of N but also on the deficiency or sufficiency of other associated plant nutrients. Thus, balanced use of all nutrients is essential because no agronomic manipulation can produce high efficiency out of an unbalanced nutrient use. Crop Rotation Involving Legumes There is need to develop crop rotations involving legumes to tap the benefits of biological nitrogen fixation (BNF). Nitrogen use efficiency for cereals following legumes is greater than that for cereals following cereals or fallow. The role of legumes in N economy is well researched but the problem is how to increase N input and the options are increased system efficiency or Page | 95
increase in the area under the system. N derived from BNF in legumes varies from 40-80 per cent and residual effect on succeeding crops is variable and depends on several factors. The more intensive systems (growing more crops in a given period of time) require greater fertilizer N inputs but are economically advantageous to farming community. More intensive dry land cropping systems involving legumes in rotation lead to increased water use efficiency and also better maintain soil quality. The research has shown a positive impact of BNF on nitrogen economy of cropping systems but the vast potential of BNF has remained unrealized at the farmers' level due to many reasons and needs to be looked into from the holistic approach on nitrogen use in agricultural production systems. Some aspects which need immediate attention are: increasing public investment in microbiology for teaching, research and training, encouraging private investment in manufacture of biofertilizers, constitution of nodal agency for registration of manufacturers, establishment of quality control laboratories and act as a watch dog and promoting products through DAVP and media. The private sector needs to play a crucial role and set an example by employing qualified microbiologists for production, assuring quality through creation of brand equity, ensuring niche marketing through entrepreneurship ventures and providing dealers' involvement as advisor and friend on product and proper application. There is an urgent need to improve the inputs of organics and BNF and to increase the production of quality inoculants and popularize their use in Indian agriculture rapidly. Development of effective and competitive strains tolerant to high temperature, drought, acidity and other abiotic stresses are of high priority. Newer formulations of mixed biofertilizers, improvement of inoculants quality and devising effective delivery systems are crucial for making further progress in taking the BNF technology to farmers' fields. Breeding Input Efficient Crop Varieties Breeding and selecting crop cultivars that make more efficient use of water and fertilizer N (including higher N fixation and N partition) while maintaining productivity and crop quality has been a long-term goal of production agriculture. Development of nitrogen-efficient cultivars could help decrease fertilizer N inputs and resulting reactive N losses to air and ground water. These nitrogen-efficient cultivars could also be useful in regions where limited-resource farmers are unable to afford synthetic N fertilizers. Selection of N efficient genotypes that is the varieties which can extract more N from soil at lower availability will enhance the production in these regions. Molecular and biotechnological approaches for searching for regulatory targets for manipulation of N use efficiency are strengthened. Unraveling the Page | 96
details of N signal transduction to provide additional clues to improve N uptake and assimilation efficiency. Holistic Crop Management for Improving Nutrient Use Efficiency
Some suggestions for holistic management of crops include:
Adopt proven methods of individual nutrient use, with knowledgeintensive nutrient management.
Harness the positive nutrient interactions and control negative nutrient interactions
Maintain natural resource base, the soil quality and prevent environmental degradation.
Use biotechnological tools for reducing the nutrient use, viz. selective ion uptake or exclusion, herbicide tolerance, B t crops, efficient strains of bioinoculant and bio-control agents and tolerance to abiotic stresses (drought, salinity, low photo- and thermosensitivity).
Multi-nutrient deficiencies are emerging and hidden hunger status for secondary and micronutrients is evident. Nutrient-use efficiency depends on several agronomic factors including tillage; time of sowing, appropriate crop variety, proper planting or seeding, adequate irrigation, weed control, pest or disease management and balanced and proper nutrient corrects nutrient use. Balanced use of plant nutrients corrects nutrient deficiency, improves soil fertility, increase nutrient and water-use efficiency, improves crop yield and farmers’ income, and better the crop and environmental quality. These factors largely influence the use efficiency, either individually or collectively. The entire crop, management practices that promote better crop growth will invariably increase the nutrient-use efficiency. Adoption of best crop management practices and precise application techniques on system basis is essential to get higher input-use efficiency and profitability. To reap the benefits of balanced use of plant nutrients, it is important to have good-quality seed, adequate moisture and better agronomic practices with greater emphasis on timeliness and precision in farm operations. References 1.
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10. García de Salamone, I.E.; Funes, J.M.; Di Salvo, L.P.; Escobar-Ortega, J.S.; D’Auria, F.; Ferrando, L.; Fernandez-Scavino, A.2012. Inoculation of paddy rice with azospirillum brasilense and pseudomonas fluorescens: Impact of plant genotypes on rhizosphere microbial communities and field crop production. Appl. Soil Ecol., 61, 196–204 11. Gogos, A.; Knauer, K.; Bucheli, T.D.2012. Nanomaterials in plant protection and fertilization: Current state, foreseen applications, and research priorities. J. Agric. Food Chem., 60, 9781–9792. 12. Goncalves da Silva MA, Muniz AS, Mannigel1 AR, Porto1 SMA, Marchetti ME, Nolla A, Grannemann I. 2011. Monitoring and evaluation of need for nitrogen fertilizer topdressing for maize leaf chlorophyll Page | 98
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Chapter - 6 Male Sterility- the Genetic Mechanisms and It’s Uses Authors Dr. Akash Singh Department of Genetics and Plant Breeding, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut-250 110 Dr. S.K. Singh Department of Genetics and Plant Breeding, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut-250 110
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Chapter - 6 Male Sterility- the Genetic Mechanisms and It’s Uses
Introduction Male sterility refers to a condition in which nonfunctional pollen grains are produced in flowering plants. In flowering plants, the first case of male sterility was reported by Koelreuter in 1763. Later on, numerous of male sterility was reported in Angiosperms. Allard (1960) and Duvick (1966) presented a good account of male sterility in flowering plants. More recently, work on male sterility has been reviewed by frankel and Galum (1977) and Kaul (1988). Male sterility is being used for development of hybrids in both tetraploid and diploid seed in various plants. Male sterility helps in reducing the cost of hybrid seed production by eliminating the process of emasculation. Male sterility is a complex heredity phenomenon, prevents the selfpollination which otherwise occurs in many plant species and hinders breeding and hybrid seed production In general cases, male sterility were an important outbreeding device which prevents autogamy and permits allogamy. Male sterile plants have non-functional or non-viable pollen grains, which are formed through a chain of vital processes during microsporogenesis. These processes are under the genetic control of many loci that mutation of any locus may result in formation of non functional pollen grains or microspores and hence male sterility. In case of male sterility occurs in nature through spontaneous mutations as well as can be induced artificially by chemical or physical mutagens. Ethidium bromide has been found effective in inducing cytoplasmic male sterility in some plants. Male sterility results from the action of nuclear genes or cytoplasmic genes or both. Male sterility is caused due to pollen or anther abortion.
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Types of Male Sterility Male sterility is of three types, viz. 1) Genetic male sterility 2) Cytoplasmic male sterility 3) Cytoplasmic genetic male sterility Almost all crop plants presses male sterility if investigated property. These are briefly discussed below: Genetic Male Sterility (GMS): The pollen sterility that is caused by nuclear genes is termed as genic or genetic male sterility. This type of sterility has been reported in several crop plants like barley, wheat, maize, cotton, sorghum, lucerne, cucurbits, tomato and sugarbeet. In majority of cases, sterility is caused by single gene. However, in few cases two or more genes control male sterility. The male sterility alleles may rise spontaneously or it can be induced artificially. A male sterile line may be maintained by crossing it with heterozygous male fertile plant, such a mating produces 1:1 male sterile and male fertile plants. Utilization in Plant Breeding: Genetic male sterility is usually recessive and monogenic hence can be used in hybrid seed production. It is used in both seed propagated crops and vegetatively propagated species. In this progeny from crosses (msms X Msms) are used as a female and are inter planted with homozygous male fertile (MsMs) pollinator. The genotypes of msms and Msms lines are identical except for the ‘ms’ locus i.e. they are isogenic and are known as male sterile A) Maintainer B) Line respectively. The female line would therefore, contain both male sterile and male fertile and male fertile plants, the later must be identified and removed before pollen shedding. This is done by identifying the male fertile plants in seeding stage either due to the pleiotrophic effect of ms gene or due to phenotypic effect of closely linked genes. In this rouguing of male fertile plant from the female is costly operation and due to this cost of hybrid seed is higher. Therefore, GMS has been exploited commercially only in few crops by few countries. E.g. In USA used in castor while in India used for hybrid seed production of Arhar (cajanus cajan).
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In cases of cotton, GMS has been reported in upland, Egyptian and arboreum cottons. In tetraploid cotton, male sterility is governed by both recessive and dominant genes. However, male sterility governed by recessive genes is used in practical plant breeding. The merits and demerits of GMS are presented below: Merits 1) Large number of parents can be used in crosses, because all the genotypes have dominant genes for male sterility. 2) Only female parents of a good hybrid has to be converted. 3) GMS generally does not have undesirable agronomic characters. 4) It is possible to breed the varieties from segregating population of GMS. Demerits 1) GMS is less stable. Sometimes, sterile plants become fertile under low temperature conditions. 2) In GMS, the lines segregate into male sterile and fertile plants in 1: 1 ratio. 3) Conversion of a genotype into GMS (ms5ms6) needs selfing after each backcross to isolate recessive genes and hence more number of generations are required. 4) It requires more area as 50% of the population is fertile. 5) The quantity of seed produced is less. 6) There is possibility of admixture if fertile plants are not properly rogued out. Cytoplasmic Male Sterility (CMS): It occurs due to the involvement of non-nuclear genes. This type of male sterility is determined by the cytoplasm. Since cytoplasm of the zygote comes from the egg cell, the progeny of such male sterile plants will always be male sterile. This type of male sterility is of importance in certain ornamental species where the vegetative part is of economic value. Usually the cytoplasm of zygote comes primarily from the eggs cell and due to this progeny of such male sterile plants would always be male sterile. CMS may be transferred easily to a given strain by using that strain as a pollinator (recurrent parent) in the successive generation of backcross programmed. After 6-7 backcrosses the nuclear genotype of male sterile line would be almost identical to that of the recurrent pollinator strain. The male Page | 107
sterile line is maintained by crossing it with pollinator strain used as a recurrent parent in backcross, since the nuclear genotype of the pollinator is identical with that of the new male sterile line. Such a male fertile line is known as maintainer line or ‘B’ line and ‘male sterile line is also known as ‘A‘line. Cytoplasmic male sterile is not influenced by environmental factor and it resides in maize in mitochondria. Utilization in Plant Breeding CMS has limited application. It cannot be used for development of hybrid, where seed is the economic product. But it can be used for producing hybrid seed in certain ornamental species or asexually propagated species like sugarcane, potato, and forage crops. Cytoplasmic Genetic Male Sterility (CGMS) Such type of sterility arises from the interaction of nuclear gene (s) conditioning sterility with sterile cytoplasm. Jones and Davis first discovered this type of male sterility in 1944 in onion. This type of male sterility has provision for restoration of fertility, which is not possible in cytoplasmic male sterility. The fertility is restored by the R gene (s) present in the nucleus This is the case of cytoplasmic male sterility, where a nuclear genes restoring fertility in the male sterile line is known. The fertility restore gene ‘R’ is dominant and found in certain strains of the species. This genes restores male fertility in the male sterile line, hence is known as restores gene. This system includes A, B, and R lines. A line is a male sterile line, B is similar to ‘A’ in all features but it is a male fertile and R is restore line it restore the fertility in the F1 hybrid. Since B line is used to maintain the fertility and is also referred as maintainer line. The plants would be male sterile line in the presence of male sterile cytoplasm if the nuclear genotype is RR, but would be male fertile if the nucleus is RR or RR. New male sterile lines may be developed following the same procedure as in the case of cytoplasmic system, but the nuclear genotype of the pollinator strain used in transfer must be the fertility would be restored. Development of new restorer strain is somewhat indirect. First a restorer strain (R) is crossed with male sterile line. The resulting male fertile plants are used as the female parent in repeated backcrosses with the strain (C) used as the recurrent parent to which transfer of restorer gene is desired. In each generation, male sterile plants are discarded and the male fertile plants are used as female for back crosses. This acts as selection device for the restores gene R during the backcross programme. At the end of back cross programme a restorer line isogenic to the strain ‘C’ would be recovered. Page | 108
Utilization in Plant Breeding: Cytoplasmic genetic male sterility is widely used for hybrid seed production of both seed propagated species and vegetatively propagated species. It is used commercially to produce hybrid seed in maize, Bajara, cotton, rice, sunflower, jowar, etc. Thus, the combination of both nuclear genes and cytoplasmic factors determines the fertility or sterility in such plants. The merits and demerits of CGMS are presented below: Merits 1) In CGMS system, CMS is highly stable and is not affected by environmental factors. 2) In CGMS system, CMS 'A' line gives only male sterile plants. 3) Conversion of a genotype in CGMS system 'A' line is quicker and direct. 4) CMS requires less area for maintenance. 5) The quantity of seed produced is more. 6) There is no chance of admixture. Demerits 1) In CGMS, only limited number of crosses can be made due to availability of limited number of restorers. 2) In CGMS, both male and female parents of the hybrid need to be converted. 3) CMS is solely controlled by cytoplasmic genes and hence it may have some adverse effect on other characters. 4) It is not possible to breed a variety from CMS line. Maintenance of Male Sterility As already mentioned in cotton, two types of male sterilities are used. Maintenance procedure for each type is given below. Maintenance of GMS Lines GMS lines is maintained by sibmating between fertile and sterile plants. The pollination is done by hand. The identification of sterile plants is easy by trained eyes and thus 50% plant population is to be rogued out. Maintenance of CMS Lines The CMS line referred to as 'A' line is maintained by crossing to its counter 'B' line (Isogenic Line). Page | 109
The 'B' line, a sterility maintainer line, is maintained by selfing.
The 'R' line, a fertility restorer line, is maintained by selfing.
Conversion into Male Sterile Lines The potential female parents of hybrids can be converted into male sterile lines. To convert in GMS background, four to five backcrosses accompanied by alternate selfing is required. Finally, a line which is heterozygous for sterility and showing 1: 1 segregation is selected having all the characters of the recurrent parent. The local genotypes with good agronomic backgrounds can be converted into CMS line by attempting five to six backcrosses. Similarly, the desired male parents can be converted into restorer lines by five to six backcrosses along-with a 'Rf’ factor. Finally, a line, which is homozygous for 'Rf’ factor is selected. Many promising varieties and elite germplasm lines have been converted into CMS and restorer lines and few in GMS background (Table-1). Male Sterility
System Genotypes
GMS (4x) CMS
LRA 5166, SRT 1, DGMS 1, HGMS 2, GAK 32A, SHGMS-9, DGMS2, SHGMS-5
CMS
GMS (2x) R line
Germplasm - G 67, DMS A-8, RCMS A-2. GSCMS-15, 34, CAK32A, C1412, C 1998, CAK 1234, LCMS 6, JK 119, DMSA 15, IC 1547 Varieties - Rajat, LH 900, Supriya, G. Cot l0, Laxmi, Abadhita, BN, K2, LRA, 5166, H 777, G. Cot 14, Ganganagar Ageti, F 414, Bhagya, Kh3, Narmada, Deviraj GMS 4, GMS 2, GAK 20A, GAK 09, SGMS 2, SGMS 4, RGMS A-2, RGMS 3,SGMS 13, GMS 4-1, GAK 15A, GAK 26A, Sujay, GAK 423, GAK 8615 NH 258, AKH 545, GSR 22, AKH 39R, LR 29, AKH 26R, AKH 1167, GSR 6, DR 6, DR 1, AKH-01-143, LR 104
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Sources of Male Sterility There are three important sources of male sterility viz. interspecific crosses, spontaneous mutations and induced mutations. These are briefly discussed as follows: Interspecific Crosses The cytoplasms of three diploid species, viz. G. anomalum, G. harknessii and G. arboreum interact with nuclear genes of G. hirsutum and produce male sterility. The cytoplasm of G. arboreum and G. anomalum are heat-sensitive and therefore less stable. The cytoplasm of G. harknessii and genome of G. hirsutum interaction produce stable and dependable cytoplasmic male-sterility in cotton over all environments, though some adverse effects on ginning outturn, micronaire value and bacterial blight susceptibility have been reported. G. harknessii was the only available source of CMS until 1997. After concerted efforts, the cytoplasmic lines with G. aridum Skovt. (D4) has been developed by the Cotton Research Unit, PDKV, Akola. A new system of CMS has also been developed at the University of Arkansas, USA wherein G. trilobum cytoplasm was utilized. The new system of cytoplasm called CMS 8 (D-8) has undergone extensive testing to eliminate undesirable effects (eg. Low fibre maturity) of the G. hirsutum nucleus interaction with the G. trilobum cytoplasm. Another different source of CMS i.e. CMS-C1 has been recently developed by using G. sturtianum cytoplasm. Very recently, a new male sterility system of cytoplasmic nuclear genic male sterility has been evolved through interspecific breeding using a synthetic allopolyploid between G. anomalum x G. thurberi at Akola. The new male sterility system enables to avoid tedious work of incorporation of R genes into cultivated species / genotypes which is the main bottleneck of CGMS. Mutations Mutation is a sudden heritable change in an organism which does not arise due to recombination or segregation. This phenomenon leads to change in a gene, resulting in male sterility. Mutations are of two types, viz. spontaneous and induced. Spontaneous male sterility has been observed in upland and arboreum cottons. Male sterility can also be induced through the use of physical and chemical mutagens. Mutagen included male sterility has been reported in as many as 35 crop Page | 111
species including cotton. In G. arboreum, the first spontaneous male sterility mutant was identified in variety DS-5 at Haryana Agricultural University, Hisar. The gene is designated as ams1. The semi and complete male sterility has been isolated by various workers from the material treated by X-rays, gamma rays and Ethyl Methane Sulphonate (EMS). At Dharwad, cotton variety Abadhita was treated with gamma rays and various concentration of EMS. Male sterile mutant was obtained in case of double mutagen at 10 kR + 0.2 per cent EMS. In M2 generation, the segregation pattern of male sterile to fertile was 1: 1, indicating presence of GMS which was conditioned by post meiotic pollen abnormality. Induction of Male Sterility by Male Gametocides Male sterility can be induced through the use of chemicals, which are commonly known as male gametocides. Some of the chemicals used for induction of male sterility is FW 450 (Sodium B Dichloro-iso-butyrate) or MH-30 (Maleic hydrazide) and Ethidium bromide (a potent mutagen). Spraying of aqueous solution of FW-450 or MH30 induces male sterility in cotton. Pate and Duncan (1960) found that application of 2-3 dichloro-isobutyrate at the rate of 1.02 lb per acre showed selective toxicity to the male gametes. Higher concentration of treatments caused male as well as female sterility and various adverse effects like reduction in yield, boll and seed size and increase in lint percentage. Singh et al. (1989) studied the effect of some gametocides on pollen sterility and anther development in G.arboreum. The effect of FW 450 (Mendok), maleic hydrazide (MH) and Coumarin applied before and during bud initiation or at anthesis were examined. Highest pollen sterility was caused by 1.5% FW-450, ranging from 76.3 to 97.8%. Treatment twice, one before bud initiation and the second during bud initiation gave the highest rate of pollen sterility. Trials with selective male gametocides like FW 450, MH etc. has not been encouraging. The new selective chemosterilants like CHA (Chemical hybridizing agent) promoted by an American Company Chembred Inc. may be tried for this purpose. Effect of Environment on Male Sterility Environmental factors like temperature, photoperiod etc. have influence on male sterility. The G. harknessii cytoplasmic male sterility is very stable and is least affected by the environmental conditions and therefore can be utilized in varying environmental condition. The CMS lines of G. hirsutum with G. arboreum and G. anomalum cytoplasm were studied and it was observed that day temperature above 33°C was required for the consistent expression of male sterility in the sterile 'A' line. Increased day length Page | 112
generally led to increased level of sterility. It was reported that male sterility in cotton was induced mainly by high temperature. Temperature above 35°C in the active crop period resulted in abortion of flower buds and splitting of anthers. Genetic male sterility is unstable and there are chances of male sterile plants becoming male fertile under low temperature condition. Out of 16 different genes reported in G. hirsutum ms5ms6 is the stable source. However, both the arboreum GMS sources were found to be temperature sensitive. The sterile plants have been found to produce pollens when the temperature falls below 16°C. This type of temperature sensitive male sterility is referred to as T GMS. The advantage of this system is that such lines do not require separate maintenance as it produces viable pollen below 16°C. Development of MS Based Hybrids Male sterility has important application in the development of hybrids. All the three types of male sterility are used in crop improvement programme. In India, several hybrids have been developed in cotton using the GMS system. CPH2 (Suguna) was the first male sterility based hybrid released in as early as 1975 from CICR Regional Station, Coimbatore. However, this GMS based hybrid did not spread much for lack of seed production efforts. The G. harknessii cytoplasmic male sterility with fertility restoration gene sources were used in developing the hybrid CAHH 468 (PKV Hy-3). A brief comparison of MS based and conventional hybrids is given in Table 2. Few private seed company hybrids also represent this category. Table-3 shows some public and private bred MS based hybrids. Table 2: Comparison of MS based and conventional hybrids MS Based Hybrids Conventional Hybrids Planting ratio for female to male is 4: 1 or Planting ratio for female to male is 2:2. 3: 1 Half day labours are required for pollination case of GMS (in few labours are required for identifying and roguing of fertile plants)
Full day labours are required for emasculation and pollination
For one kg seed production, one female labour
For one kg of seed production, three female labours are required per day.
One female labour can pollinate 20003000 flowers
One female labour can emasculate and pollinate 200- 00 flowers.
Quantity of seed produced is more due to high Seed setting as there is no mutilation of the female part.
Quantity of seed produced is less as there are more chances of mechanical injury during emasculation.
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Immature seed % is low.
Immature seed % is high.
Shedding % of crossed bolls is negligible.
Shedding % of crossed bolls is more due to mechanical injury.
Self pollinated bolls is negligible (chance only in GMS)
Self-pollinated bolls are high.
Spread of hybrids is rapid.
Spread of hybrids is slow.
Use of F2 seed as planting material is not possible.
Use of F2 seed, as planting material is possible.
Table 3: Main features of hybrids released using male sterile line Name of hybrid
Year of release
Yield (q/ha)
GOT (%)
MFL (mm)
Spinning counts
Suguna
1978
30
35
25
40
ANKUR 15
1983
30
35
26
MECH 11
1984
25
38
28
Area in which Type of released hybrid Tamil Nadu
HH
50
Vidarbha
HH
50
MS and AP
HH HH
MECH 4
1990
25-30
35
29
50
MS,GS, MP,RS
PKV HY-3 (CAHH 468)
1993
15R
36
25
40
Vidarbha
HH
PKV HY4 (CAHH 8)
1996
20R
35
30
50
Vidarbha
HH
ANKUR 09
1997
30
37
27
40
MS,GS, MP
HH
AAH 1
1999
24
38
16
250 mm), when allowed to dry and age, due to organic mucilage and/stable organo-mineral complexes and oriented clays left lined in the burrowing walls (Six et al., 2004). The effect of earthworms on the soil structure is not only mediated by abundance but also by the functional diversity of their communities (Verhulst et al., 2010). Therefore, they vary in their ecological behaviour, thus, their effect on soil structure is different. Moreover, earthworms play a major role in the recycling of nutrients and formation of stable aggregates. In addition the stability of cast depends on the quality of ingested material (Six et al., 2004). Soil Microbial Biomass (SMB) Soil microbial biomass is a reflection of soil to store and recycle nutrients, such as C, N, P & S and SOM and has a high turnover rate relative to total SOM. The dominant factor controlling the availability of SMB is the rate of C input and also availability of N resources in the soil (Six et al., 2004). A uniform and continuous supply of C from organic crop residues serves as the energy source for microorganisms. Previous studies has shown that as the total organic C pool increased or decreases, as results of changes in C input in the soil, the microbial pool also increases or decreases (Franzluebbers et al., 1999). Microorganism’s plays an important role in physical stabilization of soil aggregate and this was found to be linked to glomalin content which is an indication of degree of hyphal network development. These fungal hyphae form extended network in cultivated soil and are activated by contact with seedlings. In contrast to tillage system, in no-till conservation agriculture, the mycorrhizal system is more stable. Plow tillage promote the release and decomposition of previously protected SOM in the soil, initially increasing soil microbial biomass. The availability of nitrogen in the early stages of CA adoption usually decrease in the soil due to increase in microbial activity from surface residue decomposition and lack of incorporation in the soil and this is more pronounced in organic material with higher C/N ratios. The effect of tillage practice on SMB-C and N seems to be mainly confined in the surface layers with stronger stratification when tillage is reduced This can be attributed to higher level of C substrate available for microorganism growth, better soil physical condition and water retention under reduced tillage. Conservation Tillage and Carbon Sequestration Several study compared soil organic carbon (SOC) in conservation and conventional tillage systems. The results from analysis suggest that switching from conventional cultivation to zero till would clearly reduce on-farm
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emissions. VandenBygaart et al. (2003) found that reduced tillage increases the amount of carbon sequestered by an average of 320-150 kg C ha-1 in 35 studies of western Canada and that the removal of fallow enhanced soil carbon storage by 150-60 kg C ha-1 based on 19 Studies. West and Marland (2002) reported that carbon emission from conventional tillage (CT), reduced tillage (RT) and no tillage (NT) were respectively 72.02, 45.27, 23.26 kg C ha -1 in case of corn cultivation and 67.45, 40.70, 23.26 kg C ha -1 for soybean cultivation based on annual fossil fuel consumption and CO 2 emission from agricultural machinery. Mosier et al. (2006) reported that based on soil C sequestration, only NT soils were net sinks for GWP and economic viability and environmental conservation can be achieved by minimizing tillage and utilizing appropriate levels of fertilizer. Greenhouse Gas Emission with Conservation Agriculture In this section we deal with the net emissions of N2O and CH4 from soils as a result of CA practices. It is also important to note that there can be considerable impacts of CA compared to conventional agriculture with changes in the intensity of mechanical tillage, less irrigation, and possibly less N fertilization and the associated reduced use of fossil fuels with CA. These effects are not considered in this paper. Jain et al., 2014 estimates, on farm burning of 98.4 Mt of crop residues led to the emission of 8.57 Mt of CO, 141.15 Mt of CO2, 0.037 Mt of SOx, 0.23 Mt of NOx, 0.12 Mt of NH 3 and 1.46 Mt NMVOC, 0.65 Mt of NMHC, 1.21 Mt of particulate matter for the year 2008–0. CO2 accounted for 91.6% of the total emissions. Out of the rest (8.43%) 66% was CO, 2.2% NO, 5% NMHC and 11% NMVOC (Fig. 1 (a). Burning of rice straw contributed the maximum (40%) to this emission followed by wheat (22%) and sugarcane (20%) (Fig.4 (b). Highest emissions were from the IGP states with Uttar Pradesh accounting for 23%, followed by Punjab (22%) and Haryana (9%). Burning of agricultural residues, resulted in 70, 7 and 0.66% of C present in rice straw as CO 2, CO and CH4, emission respectively, while 20, 2.1% of N in straw is emitted as NOx and N 2O, respectively, and 17% as S in straw is emitted as SOx upon burning. Sahai et al. (2007) have measured the emission of trace gases and particulate species from burning of wheat straw in agricultural fields in Pant Nagar, Uttar Pradesh.
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Figure 1. (a) Emission of different pollutants and GHGs due to field burning of crop residues. (b) Contribution of different crops in burning (Jain et al., 2014).
Nitrous Oxide N2O is a potent and long-lived GHG, having a global warming potential 298 times that of carbon dioxide (CO2) and remaining in the atmosphere for up to 114 years. N2O is produced in soils in the microbiological processes of nitrification and denitrification. Nitrification - the oxidation of ammonium to nitrate - occurs in aerobic conditions while denitrification - the reduction of nitrate (NO3) to N2O and N2 - takes place in anaerobic conditions. The relative contribution of these two N pathways to N2O formation depends on episodic changes in soil aeration and water filled pore space (WFPS). Residues management and crop rotations can affect N2O emissions by altering the availability of NO3 − in the soil, the decomposability of C substrates. The reduction of N2O to N2 is inhibited when NO3 − and labile C concentrations are high. The retention of crop residues and higher soil C in surface soils with CA play major roles in these processes. Under anaerobic conditions associated with soil water saturation, high contents of soluble carbon or readily decomposable organic matter can significantly boost denitrification (Dalal et al., 2003) with the production of N2O favored with high quality C inputs. Methane Methane has a lifetime of 12 years and a global warming potential 25 times that of CO2 over a 100 year time horizon. Agricultural soils contribute to CH4 emissions as a result of methanogenic processes in waterlogged conditions that are usually associated with rice production. Flooded rice production contributes 15% of total global CH4 emissions (IPCC, 2010). The magnitude of CH4 emissions is primarily a function of water management with Page | 236
the addition of both mineral and organic fertilizers having a significant influence. The addition of organic fertilizers has the potential to increase emissions by over 50% relative to non-organic fertilizers. In contrast to N2O, CH4 can be consumed (oxidized) by soil microorganisms and resulting in a CH4 sink which is sensitive to both temperature and soil water content (Dalal et al., 2008). The total CH4 flux from soils is therefore the difference between the production of CH4 under anaerobic conditions and CH4 consumption. Agricultural soils, particularly those that have been fertilized, have a significantly lower CH4 oxidation rate compared to natural soils and higher oxidation rates are observed in temperate compared to tropical soils (Dalal et al., 2008). Obstacles to adoption of conservation agriculture by farming community The adoption of agricultural management practices capable of sequestering C is hampered both by environmental (weather, etc.) and sociopolitical factors. The latter constraints, including the supply and demand for agricultural products, production costs, subsidies, incentives to reduce environmental impacts and social, aesthetic and political acceptance for changes, may well be the most important factors in deciding whether or not suggestions are applied by producers. It must be understood though, that in the end, producers will only adopt new management practices if it is found to be economically feasible. Analyses of these factors are highly complex, and studies on this are in their infancy It should be emphasized that C sequestration, whether in vegetation or in soils, does not represent a ‘‘permanent’’ solution to the issue at hand. The C carbon sequestered should not ‘‘irreversibly’’ locked-up; but rather, that the build-up of offset terrestrial C stocks through changes in management is reliant on the long-term maintenance of those practices throughout time. Because C sequestration is a function of primary production and rate of organic matter decomposition, the most important factor influencing sequestration is weather (moisture and temperature). Thus, the amount of C sequestered depends on weather conditions over which we have no control. Alternate drying and wetting in some rice-based systems further complicated our understanding of the responses of alternative tillage, crop residue, and nutrient management practices. Similarly, knowledge gap in disentangling the soil C pools under diverse agro-ecosystems and management practices limits our understanding of turnover rate, storage, and loss of SOC in rice-based production systems.
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