Operational Indicators for Measuring Agricultural ... - Semantic Scholar

DOI: 10.1007/s00267-003-2881-1

Operational Indicators for Measuring Agricultural Sustainability in Developing Countries LIN ZHEN Institute of Geographic Science and Natural Resources Research Chinese Academy of Sciences PO Box 9717 Beijing 100101, P.R China JAYANT K. ROUTRAY* Regional and Rural Development Planning School of Environment Resources and Development Asian Institute of Technology P.O. Box 4 Klong Luang Pathumthani 12120, Thailand ABSTRACT / This paper reviews relevant literature on the sustainability indicators theoretically proposed and practically applied by scholars over the past 15 years. Although progress is being made in the development and critical analysis of sustainability indicators, in many cases existing or proposed indicators are not the most sensitive or useful measures in developing countries. Indicator selection needs to meet the

The academic, scientific, and policy-making communities have in recent years focused much attention on the concepts of “sustainable environment” and “sustainable development” (for example, WCED 1987, Liverman and others 1988). This interest has been accompanied by attempts to develop useful systems for measuring sustainability, including farming systems on which human beings are dependent for their subsistence. Lynam and Herdt (1989) urged agricultural researchers to recognize the importance of the sustainability of agricultural systems, devise appropriate ways of measuring sustainability, empirically examine the sustainability of some well-defined cropping or farming systems, and develop methods to measure those externalities. Sustainability indicators are increasingly seen as important tools in the assessment and implementation of KEY WORDS: Sustainable agriculture; Sustainability indicators; Indices Published online September 4, 2003. *Author to whom correspondence should be addressed, email: [email protected]

Environmental Management Vol. 32, No. 1, pp. 34 – 46

following criteria: relative availability of data representing the indicators, sensitivity to stresses on the system, existence of threshold values and guidelines, predictivity, integratability and known response to disturbances, anthropogenic stresses, and changes over time. Based on these criteria, this paper proposes a set of operational indicators for measuring agricultural sustainability in developing countries. These indicators include ecological indicators involving amounts of fertilizers and pesticides used, irrigation water used, soil nutrient content, depth to the groundwater table, water use efficiency, quality of groundwater for irrigation, and nitrate content of both groundwater and crops. Economic indicators include crop productivity, net farm income, benefit– cost ratio of production, and per capita food grain production. Social indicators encompass food self-sufficiency, equality in food and income distribution among farmers, access to resources and support services, and farmers’ knowledge and awareness of resource conservation. This article suggests that the selection of indicators representing each aspect of sustainability should be prioritized according to spatial and temporal characteristics under consideration.

sustainable farming systems. Numerous suggested indicator lists and matrices already exist (Morse and others 2001). For instance, Izac and Swift (1994) proposed a list of sustainability indicators for sub-Saharan African agrosystems. The list covers categories of yield, profit, soil resources base, drinking water, and nutritional status. Several specific indicators are included under each category. For example, potential or target yield is a proposed indicator for yield, and drinking water quality (farm scale) and availability (village scale) are proposed indicators for drinking water. However, sustainable agriculture is a time- and space-specific concept. Its assessment should be closely linked to the context in which the specific farming system is taking place. The current problem for the assessment of farming systems is how to obtain acceptable indicators spatially and temporally and how to apply and integrate these diverse indicators to address whether a particular practice is sustainable or not. This problem presents a pressing challenge for researchers. It arises in part because sustainability normally involves at least three independent but interrelated dimensions: the ecological, the economic, and the social (Tisdell ©

2003 Springer-Verlag New York Inc.

Measuring Agricultural Sustainability

Table 1. Basic dimensions and conforming levels to assess agricultural sustainabilitya Dimensions

Levels

Normative

Ecological aspects Economic aspects Social aspects Local Regional National Long-term Short-term

Spatial

Temporal a

1

2

Source: S.von Wiren-Lehr (2001).

3 1996). Sustainability on these three dimensions may be difficult to reconcile because usually each has different time-scale implications and takes different perspectives within each given context. This article attempts to (1) examine and evaluate indicators that individuals or organizations have used to measure the sustainability of farming systems based on the three dimensions of sustainability, (2) introduce a methodological framework for selecting proper indicators, and (3) propose operational indicators that can be used at the farm level in developing countries.

Definition of Sustainable Agriculture The concept of sustainable agriculture became widespread in the 1980s. At least 70 definitions can be identified in the literature. These differ in subtle ways, emphasizing different values, priorities, and goals (Pretty 1995). Attempting to arrive at a more precise, operational, and absolute definition of sustainable agriculture is exceptionally problematic, partly because there is such a range and number of parties involved in this debate (Pretty and Hine 2000, Rigby and Caceres 2001). Three dimensions and different conforming levels to assess and implement sustainability in agriculture have been defined (von Wiren-Lehr 2001); these are shown in Table 1. The concept of sustainable agriculture emphasizes different aspects of agriculture in the context of different countries and regions. Bowers (1995) argued that in developed countries, the main sustainability issues are diversification away from a limited range of commodities and the satisfaction of environmental pressure groups, particularly with respect to large losses of nutrients and the quantities of pesticides currently used. In developing countries, the imperative is to maintain food production, while preserving the underlying resource base. Sustainable agriculture in developing countries therefore implies:

4

5

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Intensive farming, thus increasing land use efficiency and productivity through diversified cropping patterns, such as intercropping, mixed cropping and multiple cropping; Maximum use of internal resources and balanced use of external resources. Balanced use of external inputs means that the use of chemical fertilizers should be based on soil nutrient status, dosage of pesticides use should refer to recommended dosages of pesticides for specific pests or diseases, and the use of irrigation water should be based on the water demand of different crops and the availability of water resources; Profitable and efficient production, with an emphasis on increased production, per capita products and net farm income; The inherent capacity of soil and water resources that support agricultural production are maintained or improved over time (Sands and Podmore 2000); and A greater productive use of local knowledge and practices, and enhanced innovation and application of resource conservation technologies.

Measurement of Sustainable Agriculture A fundamental step towards formulating policies for sustainable agricultural development is to find quantitative indicators. Unless this is done, it is impossible to judge the exact nature of change, and whether the order of development is increasing or decreasing (Lo and Xing 1999). According to Senanayake (1991), developing a quantitative measure of sustainability is an important prerequisite to the development of legislative measures for agriculture, such as those being enacted in many countries today. Sustainability indicators are the most prolific and available method for sustainability evaluation within the literature. Sustainability indicators have been defined as indicators that provide information, directly or indirectly, about the future viability of specified levels of social objectives such as material welfare, environmental quality, and natural amenity (Braat 1991). Pretty (1995) argued that: “At the farm or community level, it is possible for actors to weigh up, trade off and agree on these criteria for measuring trends in sustainability. But as we move to high levels of the hierarchy, to district, regions and countries, it becomes increasingly difficult to do this in any meaningful way.” Pretty goes on to say that when specific parameters or criteria are selected, it is possible to say whether certain trends are steady, going up, or going down. At the farm level, for example, practices causing soil to erode can be considered to

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Table 2.

L. Zhen and J. K. Routray

Sustainability indicators theoretically proposed by scholars

Sources

Economic

Social

Ecological

Barbier (1987)

Increased productivity of agroecosystems

Equity enhancing

Genetic diversity

Social justice Participation

Biological productivity

Productive technology used Land tenure systems Social relations of production Product supply and security Equity

Species of crops and livestock kept

Lynam and Herdt (1989) Simon (1989)

Brklacich and others (1991) Senanayake (1991)

Stock and others (1994)

Tisdell (1996) Smith and McDonald (1998)

Chen (2000)

Net present value Yield

Sustained yield Production viability Value of inputs and outputs

Land carrying capacity Environmental accounting Carrying capacity Residence time of soil Residence time of biota Energy ratio Power equivalents Efficiency of solar flux use Quality of water, soil, and air

Profitability

Quality of life

Productivity

Social acceptance

Energy efficiency Fish and wildlife habitat

Access to resources Skills and knowledge base available to the farmers Public awareness of conservation Planning capacity of farmers

Land capability Nutrient balance Biological activity Soil erosion

(output-input)/input Production cost Product prices Net farm income

Total agricultural products Per capita food production Net farm income

Per capita food supply Land tax Participation in decision making

be unsustainable relative to those that conserve soil. Practices that remove the habitats of insect predators or kill them directly are unsustainable compared with those that do not. Forming a local group as a forum for more effective collective action is likely to be more sustainable than individuals trying to act alone. Many indicators for assessing agricultural sustainability are found in the development, economics, and environment literatures. Walker and Reuter (1996) saw them falling into two types: condition indicators and trend indicators. Condition indicators are those that define the state of the system relative to a desired state, or those that can be used to assess the condition of the environment. Trend indicators are those that measure how the system has changed, or those that can be used to monitor trends in conditions over time. This type of indicator may be used to detect historical development trends or sudden shifts in the past, meaning retrospec-

Use of fertilizers/pesticides Water use efficiency Use of external input Ground water quality Soil erosion Per capita disaster loss Multi-cropping index

tive evaluation in a more general sense. Condition indicators characterize the overall magnitude of the difference of a particular resource subindex from the ideal state value over the simulation period (Sands and Podmore 2000). Trend indicators describe the overall linear trend of a resource subindex over the simulation period. All indicators need to be placed within the local context and to cover ecological, economic, and social aspects. The diversity of major indicators for assessing global and regional conditions and trends, in terms of the environmental, economic, and social spheres, is discussed in the following section.

Sustainability Indicators Theoretically Proposed by Scholars Table 2 summarises sustainability indicators proposed by various scholars.


Barbier (1987) reviewed the concept of sustainable economic development as applied in the Third World and, based on this review, proposed using genetic diversity, biological productivity, equity enhancing, social justice, and participation as indicators of sustainability. For instance, in rural settings, the increased productivity of agroecosystems and its equitable distribution among livelihoods can be considered as contributing to sustainability. Lynam and Herdt (1989) proposed net present value (NPV) from cost– benefit analysis as the conservation criterion in their research identifying differences between agricultural systems. They argued that a sustainable system has a nonnegative trend in total productivity over the period of concern. Thus, their measure of output is the economic value of outputs divided by the value of inputs and will depend not only on physical productivities but also on prices. If NPV is greater than or equal to one, then the system is sustainable from an economic point of view, and the farming enterprise would not operate at an economic loss. However, this measurement was challenged by Tisdell (1996), because it did not reflect profit, which is important from an economic point of view, since conservation projects will not be sustainable unless they are economic and remain so. He therefore proposed a parallel indicator: the ratio of output value less input value and divided by the input value. This indicator must satisfy the constraint or side condition that it be equal to or greater than zero, otherwise the indicator is meaningless. In his review of literature on sustainability, Simon (1989) summarized the variables proposed for use as performance indicators of agroecological systems. He considered sustainability as the central focus, linking the physical environment to local human activity and the wider political economy. The land tenure system, he argued, is an important indicator of social equity. Economists also believe that property rights, like the ownership of land, strongly determine the sustainability of land use systems (Tisdell 1996). The social relations of production represent the nature and dynamics of local political systems, such as community and household structures. Relevant issues include who within these structures controls access to household and nonhousehold labor for productive purposes. Brklacich and others (1991) proposed six indicators for assessing the sustainability of food production systems. From an economic perspective, they focused on sustained yield, meaning the output levels that can be maintained continuously, and production viability, meaning the capacity of primary producers to remain in agriculture. Social justice indicators are product sup-

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ply and security and equity. Product supply and security focuses on the adequacy of food supplies. Equity relates to the spatial and temporal distribution of products derived from resource use. Environmental accounting and carrying capacity indicators are rooted in the resource stewardship or land ethic view of resources. Environmental accounting identifies biophysical limits for agricultural production, and carrying capacity refers to the maximum population levels that can be supported in perpetuity. Many studies on sustainable agriculture include two or more of these six indicators, reflecting the complexity of the concept and the need to embrace issues relating to the biophysical, social, and economic environments. Senanayake (1991) suggested a composite index that recognizes the value of some economic and ecological aspects of sustainability in Australia. He proposes that agricultural systems have varying degrees of sustainability according to the level of external inputs required to maintain the system and the state of the biotic community within which a system operates. Several parameters that can be used to generate an index of ecological sustainability are proposed. These include external inputs (Ei), energy ratio (Er), power equivalents (Pe), efficiency of solar flux use (Se), residence time of soil (Rs), and residence time of biota (Rb). The index of ecological sustainability (S) is therefore constructed as: S ⫽ f (Ei, Er, Pe, Se, Rs, Rb). Each parameter has its own possible states ranging from two to three. For instance, the three possible states of Ei are listed as 0.1, 0.5 and 1.0. Ei is seen to be more sustainable at lower values. The terms Rs and Rb are such that only two possible states exist, namely zero and one. In the zero state the farming category is nonsustainable no matter what its other measures are. In the value state, the farming type is sustainable, but the degree of sustainability depends on the values of other parameters. In terms of agricultural sustainability, S ⫽ Rs ⫻ Rb/关 f 共Ve兲 ⫺ f 共Vd兲兴 where Vd ⫽ f 共Ei,Er,Pe,兲 Ve ⫽ f 共Se,Pr,兲 Thus, any farming system type that contributes to physical erosion or a high rate of soil biomass loss will yield a value of zero and can be termed nonsustainable. A farming type that conserves these basic resources will demonstrate a positive value, and therefore be termed potentially sustainable. This type of sustainability index could be a useful tool in evaluating the relative sustainability of agricul-

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tural systems. It will be necessary to test such an index in the field in a variety of land systems and farm enterprises. The use of such an approach will assist in the design of more sustainable agricultural systems. Stock and others (1994) derived a scheme based on the quantification of constraints on agricultural sustainability in the United States. They proposed a framework for evaluating the relative sustainability of a farming system using nine attributes: profitability, productivity, soil quality, water quality, air quality, energy efficiency, fish and wildlife habitat, quality of life, and social acceptance. Their proposed scheme includes a list of constraints for each attribute. A key element in the scheme is the quantification of specific constraints within each attribute. A system is evaluated by assigning weights to each attribute, scoring the attributes of the proposed system based on the specific constraints of each attribute, and then combining the weights and scores to produce a figure of merit. For instance, quantifiable constraints for the attribute of profitability are listed as decreasing farm income and increased dependence on credit. Increasing or steadily high erosion rates, decreasing organic matter content and cation exchange capacity, increasing salinization and alkalization of soils, decreasing infiltration and water holding capacity, and decreasing earthworm activity are all measurable constraints of soil quality. Increasing complaints about food safety, quality of drinking water, long-term adequacy of food supply, and health threats from agriculture are constraints on the attribute of social acceptance. If all attributes are within a satisfactory range, the score needs to reflect the relative merit of each system. Since there may be many constraints for each attribute, each constraint must be scored individually. With this approach, any constraints chosen for the evaluation scheme must be amenable to numerical definition (e.g., dollars of net income). Based on this research, the constraints that can be quantified by direct measurement are those related to profitability, productivity, water quality, and energy efficiency. Constraints not readily measurable will need other evaluation techniques, including expert opinion and computer simulation models. This approach incorporates the necessary elements and procedures to allow progress toward comparing the relative sustainability of many production systems in use today or proposed for the future. The approach can be used with a computeraided decision support system, where expert opinions and dynamic simulation models can be integrated as supporting tools. In “Assessing the Sustainability of Agriculture at the Planning Stage,” Smith and McDonald (1998) recently proposed some important indicators to assess the sus-

tainability of farming practices in Australia. From an economic point of view, they argued that profitability indicators such as total production and net farm income are the primary indicators of agricultural sustainability. From an environmental point of view, they focused on trends in land and water use, since these affect long-term production. Increasing water use efficiency, nutrient replacement, maintenance of biodiversity, and declining soil loss were viewed as potential sustainability indicators. Social indicators were also equally important for assessing sustainability. Smith and McDonald argued that there are important threshold values for the assessment of sustainability. A system becomes more sustainable if it adopts practices such as rotations without legumes, fragmented cultivation, and bare fallows, but would become less sustainable if it adopts practices such as excessive fertilizer and pesticide use and excessive irrigation and waterlogging. Chen (2000) recommended indicators to assess agricultural sustainability in the Chinese context based on population pressure, ecoenvironmental degradation, insufficient natural resources, and improper management of resources. The challenge is to consider balanced development between environment, resources, population, and economic and social components. Per capita food production, net farm income, farmers’ participation in decision-making, land taxes, inputs used, groundwater quality, and soil erosion were all prioritized indicators for measuring sustainability.

Sustainability Indicators Practically Applied by Scholars The Food and Agricultural Organisation (FAO 2000) has applied indicators such as the ratio of agricultural land to agricultural population, gross production of food products, and the share of agriculture in gross domestic product (GDP) to assess the general situation of agricultural production in developing countries (Table 3). Sands and Podmore (2000) applied the environmental sustainability index (ESI) as an indicator to assess sustainability of agricultural systems and applied it to farms in southeastern Colorado, USA. The most important contribution of this research is that it provided advice as to how individual sustainable indicators can be integrated to provide an overall picture of sustainability. ESI represents a group of 15 sustainability subindices including soil (P) and water (GW) subindices, losses from the agricultural system via surface processes (S) and leaching (L). Computation of ESI involves two fundamental steps: (1) simulation of crop management system performance over a selected time


Table 3. Sustainability indicators practically applied by FAO and scholars Sources FAO (2000)

Tellarini and Caporali (2000) Sands and Podmore (2000)

Morse and others (2001)

Indicators Ratio of agricultural land to agricultural population Irrigation land as proportion of agricultural land Gross production of food products Gross livestock products Share of agriculture in GDP Monetary input and output Energy input and output Topsoil depth Soil organic carbon Bulk density Depth to ground water Gross annual aquifer recharge budget Specific yield of the aquifer formation Crop protection Firewood and water resources Crop/tree/production Labor Credit

frame, and (2) computation of ESI based on simulation model outputs (Sands and Podmore 2000). Topsoil depth, soil organic carbon, bulk density, and depth of groundwater were among a group of 15 indicators derived from the long-term simulation. As proposed, ESI reflects the degree of unsustainability when ⬎ 0, and 0 reflects a condition of sustainability, according to the previously described framework for sustainability. The results show that the bulk density and available water holding capacity subindices are the most influential in representing differences in sustainability among the case study crop management systems. Tellarini and Caporali (2000) used the measures of monetary value and energy value to compare the sustainability of two farms— one with high inputs, and the other with low inputs—in central Italy. Structural and functional agroecosystem performance indicators calculated according to energy consumption, rather than monetary values, were found to be more meaningful in both designing of sustainable farming systems and in decision-making processes. They concluded that the farm with low inputs contributes less to the production of goods and services for final consumption but provides higher quality energy in the form of animal products. It also consumes fewer nonrenewable resources.

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Morse and others (2001) in “Sustainability Indicators: The Problem of Integration,” discussed the integration of sustainability indicators by drawing upon the results of a 6-year research project in a village in Nigeria. They chose some indicators to provide a mix of components pointing towards sustainability and unsustainability. Indicators labeled for sustainability were crop protection (less pesticides used in the late 1990s and less pest attacks occurred), water resources (improved availability, consumption, quality and water harvesting techniques), and labor participation (increased participation), credit provision (a healthy and positive force for sustainability). Indicators labeled for unsustainability were crop production (in this research, cereal–legume dynamics appeared to be a good indicator of unsustainability, since increasing legume cultivation seemed to point towards an increasing problem with soil quality) and decline in the quality of firewood. These recent contributions imply that progress is being made in the development and critical analysis of sustainability indicators. However, in many cases existing or proposed indicators are not the most sensitive or useful measures for developing countries, and even some useful indicators cannot be applied at a local level due to the unavailability of threshold values. The use of fertilizers and the use of pesticides, for example, have been proposed as ecological indicators. However, there is no universal threshold value for these indicators. The quantity and time of the application depend on local conditions such as soil nutrient conditions, varieties of crops cultivated, and the types of the fertilizers and pesticides. Therefore, a threshold value is required in order to assess the nature of the fertilizer and pesticide used at a specific farm site. A threshold value is normally absent at the local level. Some ecologists have been critical of using carrying capacity or potential yield to assess sustainability because of the difficulties in establishing appropriate threshold measures (Liverman and others 1988). There are likewise different views on the evaluation of indicators in the literature. Indicators should be interpreted carefully since their implication varies spatially and temporally. For instance, the assessment of the level of external inputs such as fertilizers, pesticides, and irrigation should be closely linked to the local context. Tisdell (1996) agreed that high-external input agriculture is unsustainable, and low input practices are considered as sustainable. Many scientists also believe that some increase in external inputs is ecologically benign if nutrient levels and organic material in the soil are maintained and that this is a necessary condition for agricultural sustainability (Barbier 1987, Webster 1997,

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Table 4.


Contingency table for inferring sustainability based on trends of system inputs and outputs

Outputs

Inputs

Decreasing Decreasing Constant Increasing

Constant Indeterminate Sustainable Sustainable

Increasing Unsustainable Sustainable Sustainable

Unsustainable Unsustainable Indeterminate

Source: Smith and McDonald (1998).

Huda 2000, Jager 2001). Hansen (1996) described how inadequate input levels degrade resources through exhaustion. In China it has been shown that increased application of chemical fertilizers does not always lead to soil fertility reduction, since the amount of plant residues increases with the application of fertilizers, thereby increasing the total quantity of crop residue returned to the field. This, in fact, leads to increased soil fertility (Liu 1995, 2000, Chen 2000, Wu 1999). Table 4 shows the sustainability of farming systems based on input and output trend. Similarly, the percentage of fallow land is not applicable as an indicator for sustainability in developing countries. Pressure on land has led to deforestation, reduced fallow land, decreased farm size, and soil erosion (Ndiaye and Sofranko 1994). In China, the per capita agricultural land area is only 0.12 ha, compared with 1.74 ha in Canada, 0.76 ha in the USA, 0.20 ha in India, and 0.28 ha globally (Cai and Smith 1994). In order to feed a large population, land is used very intensively, and a fallow system does not exist in areas such as the North China Plain. Sustainability is not an absolute concept, but with organic farming systems have the potential to be more or less sustainable (Atkinson and McKinlay 1997). For example, many researchers believe that organic farming has an overall positive effect on the landscape and nature production (Rasul 1999, MacNaeidhhee and Culleton 2000, Rossi and Nota 2000). However, Edwards and Howells (2001) argued in their research on the sustainability of crop protection in organic farming systems that organic farming systems are not sustainable in the strictest sense. Considerable amounts of energy input are needed in organic farming systems. The majority of compounds utilized in crop protection are derived from nonrenewable sources and incur processing and transport costs prior to application. Further, these compounds are not necessarily without toxicological hazards to ecology or humans. Despite these problems, the authors concluded that, in a biophysical sense, organic farming is more sustainable than conventional farming.

Criteria for Selecting Indicators Selection of effective indicators is the key to the overall success of any monitoring program (Dale and Beleyer 2001). An indicator must be selected carefully so that it can measure and describe explicitly the condition of sustainability. Dale and Beyeler (2001) have recently proposed that criteria for selecting ecological indicators should: 1 2 3 4 5 6

7 8

be easily measurable, be sensitive to stresses on the system, respond to stress in a predictable manner, be anticipatory, meaning that they signify an impending change in the ecological system, predict changes that can be averted by management actions, be integrative, meaning that the full suite of indicators provides a measure of coverage of the key gradients across the ecological systems (such as soils, vegetation types and temperature), have a known response to natural disturbances, anthropogenic stresses, and changes over time, and have low variability in response.

Some other criteria are also discussed in the literature for the selection of indicators (Liverman and others 1988, Braat 1991). To summarize, the aspects listed below should be taken into consideration for selections of indicators for assessing agricultural sustainability in developing countries. Relative Availability of Data Representing the Indicators Despite progress in developing environmental monitoring systems and data collection networks, problems still exist with data availability. For instance, data on nutritional levels and ecological changes in remote areas are particularly difficult to obtain and require careful sampling and the use of surrogate measures or remote sensing. Often such data are only reported and available for small areas or case studies and cannot be used for time series analysis or comparative work (Liv-


erman and others 1988). Therefore, data for measuring the indicator should be relatively easily available for collection and use. Sensitivity to Stresses on the System Dale and Beyeler (2001) present a strong case that the most useful indicators are those that display high sensitivity to a particular and perhaps subtle stress, thereby serving as an early indicator of reduced system integrity; other indicators may respond to all dramatic changes in the system. The selection of indicators should reflect the sensitivity to stresses on the system, which will depend on the nature of the problems or issues taken for study. Existence of Threshold Values and Guidelines The evaluation of each indicator should ideally be based on threshold values given or established locally by research institutes, government agencies, and NGOs working at the local levels. Threshold values are defined as analytically based reference values, for example, a maximum allowable ambient concentration of sulfur dioxide (Braat 1991) or maximum allowable concentration of nitrate in groundwater (Zhen and Routray 2002). Three types of threshold values can be used to evaluate indicator values (Walker and Reuter 1996): historical levels (prefarming, predisturbance), desired levels (set by research groups), and potential levels and threshold levels (set by biophysical constraints or from tables compiled from research and measurement). The threshold guidelines and the overall ranges expected for each indicator should also be identified. Indicators can thus take into account local conditions and acceptable ranges for the area. Walker and Reuter (1996) divided the values of thresholds into five ranges: “very good” and “good” mean that there is no indication of a problem or a problematic trend. “Fair” means a borderline condition for sustainability, with some actions needed to address a problem, or more detailed information needs to be sought to suggest how to stop a declining condition. “Poor” and “very poor” mean that there is an indication of a problem or a problematic trend, with a situation becoming more “serious,” or the danger of decreased sustainability increasing. Predictivity A valuable indicator should predict changes that can be averted by management action (Dale and Beyeler 2001) and can provide direct information about the future state and development of relevant socioeconomic and environmental variables. The indicator response should also be unambiguous and predictable

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even if the indicator responds to stress caused by gradual change (Dale and Beyeler 2001). This information constitutes the basis for anticipatory planning and management. Indicators that can predict unsustainable conditions have tremendous value for managers and planners (Liverman and others 1988). Time series can be used in predictive extrapolation or simulation modeling, and global modelers have used a combination of empirical estimates and theoretical assumptions to warn of potentially “non-sustainable” futures (Meadows and others 1972, cited in Liverman and others 1988). Integratability Composite indicators that integrate various measures into an index can be useful tools for measuring sustainability. A full suite of indicators for a site should integrate key environmental gradients across the ecological systems, such as gradients across soils, vegetation types, temperature, space, and time (Dale and Beyeler 2001). Indicators of soil erosion potential, for example, include measures of soil structure, slopes, cropping intensity, and natural conditions such as wind and rainfall strength. In some studies of sustainability, researchers have adopted a quantitative integration approach, whereby indicators are given numerical values and integrated mathematically to produce a value for sustainability (Walker and Reuter 1996). Known Response to Disturbances, Anthropogenic Stresses, and Changes over Time An indicator should have a well-documented reaction to both natural disturbance and to anthropogenic stresses in the system (Dale and Beyeler 2001). This criterion would pertain to conditions that have been extensively studied and that have a clearly established pattern of response. One example cited by Dale and Beyeler (2001) was focal species. Focal species are often the only species that have a large enough foundation of information to indicate long-term trends and responses to change.

Proposed Operational Indicators for Measuring Agricultural Sustainability in Developing Countries This review presents an overview of sustainability indicators theoretically proposed and practically applied by scholars and criteria for indicator selection. However, in many cases existing or proposed indicators are not the most useful measures. For instance, many indicators change with the passage of time, as most indicators have several dimensions. Land carrying ca-

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pacity is also a difficult indicator to specify. It may vary, for example, according to the type of agricultural practices and with the passage of time. Moreover, some ecologists have been critical of using carrying capacity or sustained yield to assess sustainability because of farm income. The greatest difficulties are in establishing appropriate threshold measures (Liverman and others 1988). It is also exceptionally difficult to specify a threshold value for some social indicators, such as women’s participation in farm work and decision-making. Identification of threshold values or critical values for knowledge and technology systems is similarly difficult. Based on the above review, and particularly criteria for indicator selection, a set of operational indicators for measuring agricultural sustainability at the farm level in developing countries is proposed (Figure 1). Economic Indicators Economic indicators are used to measure the productivity, profitability, and stability of farming activities. Productivity is the efficiency of input on output. Productivity is measured from two standpoints: technical efficiency of resources, expressed in terms of physical amounts, and economic efficiency in terms of monetary value (Rasul 1999). Yield per hectare is used to measure the productivity of the land. Nondeclining crop productivity is an important indicator for measuring sustainable agricultural development from an economic point of view. Net farm income implies income from crop production, which should be greater than zero in order to satisfy conditions for sustainability. In other words, gross income of production should be able to cover total variable costs per unit of land area; then crop production is profitable. Likewise, the benefit– cost ratio (BCR) of production also reflects the profitability of crop production. From the perspective of sustainability, BCR must satisfy the condition that it be greater than one. Per capita food grain production can be used to reflect food self-sufficiency, as it can be compared with the value of per capita food grain consumption. Increased per capita grain production strengthens food security. Social Indicators Food self-sufficiency is measured to analyze the food security situation of individual farmers. Concerns over food security extend beyond whether supplies will be sufficient to meet dietary and consumption requirements, and self-sufficiency is often included in the assessment of sustainable agriculture. Increasingly, it is recognized that a secure food supply, meaning one accessible to all members of a society, is a vital compo-

nent of a sustainable food production system (Brklacich and others 1991). Equality in food and income distribution among farmers can reflect social equality. There should not be too great a gap between large and small farmers regarding income and food distribution. Equal access to resources such as per capita availability of arable land, irrigation water, and support services such as extension and training services, marketing, and credit services among farmers are considered as underlying factors ensuring sustainability. In developing countries, access to extension and credit services usually favors large farmers (Axinn 1988, Dang 2001). With many developing countries having such a high proportion of small farmers, equality in accessing support services can ensure social stability and encourage farmers to improve production while conserving resources. Although farmers’ knowledge and awareness of resource conservation cannot be assessed quantitatively due to difficulties in identifying thresholds, these are important factors motivating farmers’ adoption of environmentally sound and economically profitable farming practices. Ecological Indicators Water and soil are two fundamental resources for ensuring sustainable agricultural production in developing countries. Ecological indicators are used to measure soil fertility management and water management. Quantities of chemical fertilizers and pesticides used per unit of cropped land implies that the rates of fertilizer and pesticide application should be based on soil fertility status and the level of occurrence of pests and diseases. Overuse of these inputs may lead to leaching of fertilizer and pesticides into soil and groundwater, to increased nitrate content of soil, groundwater, and crops, and to diverse human health problems. Within a specified area and time span, use of renewable resources should not exceed the formation of new stocks. For instance, yearly extraction of groundwater should not exceed the yearly recharge of groundwater reserves from rain and surface water. Therefore, the amount of irrigation water should be based on water demand by different crops during the growth period. Soil nutrient contents, particularly organic matter, N, P2O5, and K2O, are good indicators of soil fertility management practices. There should be threshold guidelines for the assessment of soil nutrient status. For example, studies conducted by the Chinese Academy of Sciences (CAS 2000) showed that soil nutrient content in the North China Plain, as represented by organic matter, N, P2O5, and K2O content, has been increasing over the past 20 years. In 2001, soil nutrient status, as reflected by organic matter, N, P2O5, and K2O content,


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Figure 1. Proposed operational indicators for measuring agricultural sustainability in developing countries.

was classified as fair to good according to threshold guidelines defined. This implies that soil fertility management practices in the area did not create serious problems for soil nutrient content. The depth of the groundwater table is a trend indicator used to assess water management practices. A decline in the groundwater table is a good indicator of overextraction of groundwater. For instance, in the

North China Plain, average annual water table decline was found to be 0.21 m over the past 30 years (Zhen and Routray 2002). The main reason identified was the overexploitation of groundwater by farmers. The quality of groundwater for irrigation should also be considered as an indicator for sustainable agricultural practices. For example, overuse of groundwater with a salt content above the maximum permissible level leads to

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Table 5. Indicator selection considering spatial, temporal, and three dimensiona characteristics of sustainability in developing countriesb Spatial

Short term (1–5 years)

Middle term (5–10 years)

Long term (10 –20 years)

National Regional (province/state) Local (district/sub-district)

1⬎2⬎3 1⬎2⬎3 1⬎2⬎3

3⬎1⫽2 3⬎1⫽2 1⬎2⫽3

1⫽2⫽3 1⫽2⫽3 1⫽2⫽3

a

1 ⫽ Economic sustainability; 2 ⫽ Social sustainability; 3 ⫽ Ecological sustainability. ⬎ refers to prioritized; ⫽ refers to equal.

b

soil salinity and compacting of the soil (CAS 2000). Appropriate irrigation methods should be selected in order to avoid negative environmental and socioeconomic impacts. Water use efficiency means the output gained from water provided during the growth period. It is an indicator of the efficiency of irrigation methods and water utilization situation. A high value of water use efficiency implies greater potential to conserve water resources. The nitrate content of groundwater and crops is a direct measurement of soil fertility management practices. Zhang (1995), in an investigation of 14 counties in the North China Plain, found that excessive nitrogen fertilization is the main cause of high nitrate content in groundwater and crops. If the nitrate content approaches its threshold value, there are potential problems to human health. An indicator’s selection and application must be both space- and time-specific, due to spatial and temporal characteristics of the indicator. Indicators representing the three dimensions of sustainability (economic, social, and ecological) should be prioritized as per the spatial characteristics under concern (Table 5). For short-term development, indicator selection at national, regional, and local levels in developing countries should first take into consideration economic and social aspects, and then the ecological aspect, since the main purpose of production is to maintain livelihoods in a short term. For medium-term development, indicator selection at the national and regional levels should first take into consideration the ecological aspect and then give equal priority to economic and social aspects. At the local level, indicator selection should consider the economic aspect first, and then give equal priority to social and ecological aspects, because increased economic benefit is still the basic concern for developing countries, which is particularly the case at the local level. For long-term development, however, indicator selection at different levels should give equal priority to all three dimensions of sustainability. By doing so, agricultural sustainability could be achieved while providing for current subsistence.

Conclusions This paper focuses on indicators proposed and used for the assessment of agricultural sustainability. The concept of agricultural sustainability is a dynamic one, in the sense that what is sustainable in one area may not be so elsewhere, and what was considered sustainable at one point in time might not be so at present or in the future because of changing conditions and people’s attitudes. In addition, sustainability varies with the frame of reference in which it is concerned, particularly with respect to sociocultural, economic, and political factors (Lefroy and others 2000). This characteristic of sustainability makes assessment exceptionally difficult. The review of indicators theoretically proposed and practically applied by organizations and scholars provides a general picture of how indicators are proposed and used for measuring agricultural sustainability. However, one cannot simply choose from the available list of indicators and apply these universally. Therefore, it is important to evaluate the sustainability of specific farming practices by developing site-specific indicators within a specific time frame. This article has proposed a set of indicators for the measurement of sustainability of farming practices in developing countries. It has also proposed criteria that can be used for the selection of operational indicators at the farm level in developing countries. In many cases, limitations of the framing indicators relate to a lack of time series data, and very often is linked to unreliable data sets. However, at the farm level, one should always take into account the opinions and assessment criteria of farmers. It is hoped that the proposed procedures and criteria elucidated in this article will provide a basis for practical application.

Acknowledgements The authors would like to extend special thanks to Dr. Virginia H. Dale and three other anonymous reviewers for their constructive comments and suggestions in improving the quality of this paper. The authors gratefully acknowledge the comments and


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suggestions received from Dr. G. B. Thapa, Associate Professor, School of Environment, Resources and Development, AIT, on the earlier version of this paper. The authors also acknowledge Dr. Jonathan Shaw, Associate Professor of AIT Extension for making a thorough proofreading of the article. This article is based on the review of the first author’s doctoral dissertation, entitled “Sustainability of Farming Practices in Ningjin County of Shandong Province, the North China Plain,” supervised by the second author. Financial support was received from AIT, AITNTNU (Norwegian University of Science and Technology) Project of Cooperation, Regional Office of Food and Agricultural Organisation for Asia and the Pacific, and the Chinese Academy of Sciences, Beijing and is gratefully acknowledged. This research is under the auspice of the National Key Project for Basic Research on Agricultural Environment (2002CB111506), the Ministry of Science and technology, P.R. China.

Dang, N. V. 2001. Farm household development in the midlands of Vietnam: a case study of Doan Hung District, PHU THO province. Master’s thesis. Asian Institute of Technology, Bangkok, Thailand 250 (in Chinese).

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