Journal of Cleaner Production xxx (2015) 1e10
Contents lists available at ScienceDirect
Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro
Environmental assessment of tropical perennial crops: the case of the Brazilian cashew a Brito de Figueire ^do a, *, Jose Potting b, Luiz Augusto Lopes Serrano a, Maria Cle Marlos Alves Bezerra a, Viviane da Silva Barros c, Rubens Sonsol Gondim a, Thomas Nemecek d , Brazil Embrapa Tropical Agroindustry, Ceara KTH Royal Institute of Technology, Stockholm, Sweden Semi-arid Federal University, Rio Grande do Norte, Brazil d Agroscope, Institute for Sustainability Sciences, Zurich, Switzerland a
b c
a r t i c l e i n f o
a b s t r a c t
Article history: Received 13 March 2015 Received in revised form 29 May 2015 Accepted 29 May 2015 Available online xxx
This study is an original environmental assessment of the Brazilian cashew, a perennial tree cultivated in 30 tropical countries that yields four products: nuts, apples, gum and wood. While economic and agronomic data regarding cashew are available worldwide, the environmental issues related to the main production systems and products commercialized by Brazilian farms have not been discussed consistently. This environmental assessment is important to guide the efforts of researchers and farmers for improving the environmental performance of cashew cropping systems and products. Life cycle assessment is applied to assess the environmental impacts of cashew systems and products, considering multi-cropping systems, agriculture functions and allocation procedures. Two cashew cropping systems are compared: (i) a high-input system, or reference system, developed through 20 years of research, and (ii) a low input system, as defined by a sample of farms practicing multi-cropping systems. Aspects and impacts of these systems are reported via the following production stages: nursery, establishment, and low and full production. Two agriculture functions are adopted to analyze the cropping systems: land management (impacts per hectare) and financial (impact per US$ from total sales receipts). The impacts of cashew products are evaluated using the crop production function (per kilogram of product). The impacts of products are measured using both mass and economic allocation. This study shows that the low and full production stages account for the majority of impact in both cropping systems, but land transformation for the establishment of cashew orchards is the main contributor of climate change. The analysis of multiple agriculture function shows different results for the study of cashew production systems and products. Considering the land management function (impacts per hectare), the low-input system causes less significant environmental impact, when compared to the high-input system, in all categories but toxicity. When the financial function is analyzed (impacts per US$ from total sales receipts from one ha), the low-input system achieves better performance for only eutrophication and water depletion impact categories. The analysis of the crop production function (impacts per kilogram of product) shows that the choice of allocation procedure also affects the results when comparing the impact values of products from different cropping systems. If the choice is for mass allocation, products from the low-input system achieve better environmental performance, but if economic allocation is chosen, products from the high-input system perform equal or better than when produced in the lowinput system. From the joint analysis of agriculture functions, the conclusion is that the best option to improve the environmental performance of the Brazilian cashew production is to adjust the high-input system with modifications regarding fertilization and pest management. From this case study, the benefits of considering multi-agriculture functions and accounting for all production stages in the study of perennial crops are highlighted. The importance of developing emission and characterization factors to
Keywords: Life cycle assessment Cashew nut Cashew apple Cashew gum Cashew wood Anacardium occidentale
* Corresponding author. ^do). E-mail address: clea.fi
[email protected] (M.C. Brito de Figueire http://dx.doi.org/10.1016/j.jclepro.2015.05.134 0959-6526/© 2015 Elsevier Ltd. All rights reserved.
^do, M.C., et al., Environmental assessment of tropical perennial crops: the case of the Brazilian Please cite this article in press as: Brito de Figueire cashew, Journal of Cleaner Production (2015), http://dx.doi.org/10.1016/j.jclepro.2015.05.134
M.C. Brito de Figueir^edo et al. / Journal of Cleaner Production xxx (2015) 1e10
2
reduce uncertainty when estimating pollutant loads and evaluating impacts of perennial crops cultivated in tropical regions is also discussed. This study advances the knowledge base on the environmental assessment of perennial crops in general, and on cashew crops specifically. © 2015 Elsevier Ltd. All rights reserved.
1. Introduction Perennial crops refer to plants with at least two life years and more than one harvest without requiring replanting. This group of crops includes many herbaceous plants and woody trees (e.g. grassland species, oilseeds, nuts and fruits) (Bessou et al., 2013). Perennials are expected to provide greater protection against soil erosion, retain more water and nutrients, store more carbon in biomass, and be more resilient to pests compared to annual crops (Cox et al., 2006). Nonetheless, life cycle assessments (LCAs) of perennial crops are more complex than those concerning annual crops, because production may start only after some years and orchards may last longer than 20 years, making it difficult to gather data for all production stages. This fact has resulted in a limited number of LCAs having been performed for perennials to date. Bessou et al. (2013) and Cerutti et al. (2014) reviewed LCA studies of perennials and showed that the main crops evaluated are energy crops (palm oil and sugar cane), oil crops (coconut and olive oil) and fruits (apples, bananas, kiwifruits, pineapples, oranges, pears, coffee, grapes and cocoa). According to these reviews, studies of perennials usually focus on the global warming impact category, do not inventory inputs and outputs from land transformation, adopt emission factors developed for arable crops in temperate regions, and apply the crop production functional unit, evaluating impacts per kilogram of harvested crops only, instead of including potential co-products and impacts of the whole cropping system. These modeling decisions may cause results of perennial LCAs to be highly uncertain and restricted to a small number of impact categories only. In order to improve the environmental analysis of perennial crops, Bessou et al. (2013) and Cerutti et al. (2014) recommended that new studies consider the following aspects: all stages of the perennial cycle (nursery, low and full production, and senescence), use of region-specific and crop-specific (when available) emission factors, and the multi-functionality of cropping systems. The cashew (Anacardium occidentale) is a perennial tropical tree that has not yet been covered in published LCAs. The cashew tree yields four products: nut (CN), apple (CA), gum (CG) and wood (CW). Consumers and companies all over the world utilize the CN themselves, or in processed form as an ingredient in a diverse range of foods (for instance, snacks, sauces, protein concentrates, etc.). CA is used by national juice and candy companies, making the cashew LCA of interest for many production chains. Furthermore, CG is a new product that can be extracted from the cashew trunk and sold to the food industry, since it has many functions including as an emulsifying, stabilizing, binding, and encapsulating agent (Oliveira et al., 2009). The renewal of orchards after 20 years of production also generates CW, which is usually used by potteries as a renewable fuel. Cashew production has high socioeconomic importance for the and Rio Brazilian semi-arid region, especially for the States of Ceara Grande do Norte, where most of the producing area is located. In 2014, cashew nut responded for 89% of Brazilian nut exports (US$ 127,731,463) (Ministry of Development, Industry and Foreign Trade, 2015), the United States being the major importer. INC, 2013, cashew farms occupied 708,808 ha and employed about 62 thousand rural workers in the Brazilian semi-arid region (IBGE, 2015; Araújo, 2013).
In the 1980s, Embrapa Tropical Agroindustry started a breeding research program to improve CN and CA yields. The program resulted in the selection and propagation by grafting of dwarf cashew trees that are resistant to pests and diseases, and have high yields of CN (up to 43 kg plant1 year1) and CA (up to 430 kg plant1 year1) (Araújo, 2013). This paper describes a comprehensive LCA of dwarf cashew cropping systems and products, adopting the abovementioned recommendations of Bessou et al. (2013) and Cerutti et al. (2014). From this study, critical gaps in the data and methods that challenge the evaluation of perennial crops in tropical regions are discussed. This advances the knowledge base on perennial crops in general, and on cashew crops specifically, since only a few published environmental assessments have focused on the identification of possible impacts in the cashew value chain (Clay, 2004). This study is original, and supports discussions and decisions regarding the environmental assessment of tropical perennial crops and, particularly, of cashew production. 2. Methods This study followed ISO 14040 (2006) and ISO 14044 (2006) to perform an LCA in order to quantify the environmental performance of Brazilian dwarf cashew systems and products (that is, CN, CA, CG and CW). 2.1. Scope, function and functional unit This study comprises all processes, from cradle to farm exit-gate in the Brazilian dwarf cashew system. This encompasses the production and transport of the inputs used by farms (agrochemicals, plastics and fuel), as well as the growing and harvesting of cashew products leaving the farm. For this study, one hectare of a dwarf cashew system was studied over 20 years. The 20-year period represents the typical lifespan of a dwarf cashew orchard, including the following cashew production stages: nursery, establishment (includes land preparation and planting during the first year), low production (four years) and full production (years six to 20). Two cropping systems are compared: (i) a high-input system, or reference system (REF-farm), developed through 20 years of research, and (ii) a low input system (LI-farm), as defined by a sample of farms practicing this cropping system. The comparison of cropping systems considers two different functions of agriculture, as proposed by Nemecek et al. (2011): (i) land management function, showing the impacts of the cropping system per area unit; and (ii) financial function, presenting impacts of the cropping system per dollar earned by the farmer with the commercialization of all products cultivated in one ha. The tree density of 208 trees ha1 is the same for the REF-farm and LI-farm. The impacts of cashew products (CN, CA, CG and CW) are also evaluated. The agriculture productive function (Nemecek et al., 2011) is used and impacts are presented per kilogram of product. 2.2. Allocation procedure Allocation is necessary for the productive function expressing impacts per kilogram, due to the multiple cashew products with varying prices harvested from one dwarf cashew tree (CN, CA, CG
^do, M.C., et al., Environmental assessment of tropical perennial crops: the case of the Brazilian Please cite this article in press as: Brito de Figueire cashew, Journal of Cleaner Production (2015), http://dx.doi.org/10.1016/j.jclepro.2015.05.134
M.C. Brito de Figueir^edo et al. / Journal of Cleaner Production xxx (2015) 1e10
3
pits, which are then filled with a mixture of surface soil, micronutrients, bovine manure and simple superphosphate at the REFfarm, or only with bovine manure at the LI-farm. Post-planting fertilization at the REF-farm is based on nitrogen and potassium fertilization and at the LI-farm on nitrogen from manure. Manual pruning is practiced in both systems to take out stems, which emerge from the rootstock, and flowers, to foster plant growth. In this first year, both farm systems use localized irrigation at the pits, four times per month during the dry season (from May to December). Low production (years 2e6): Dwarf cashew plants grow until the sixth year after planting, when they achieve growth stability. During each production year, the trees have a low and intense vegetative growth: low growth in the rainy season (JanuaryeApril) and intense growth in the dry season (MayeDecember). During the intense growth period, the leaves fall, and flowering and fructification occur. Cashew orchards are rain fed from the second year onwards. Fertilization intended to facilitate plant growth occurs in the rainy season (JanuaryeApril). The REF-farm uses manure and mineral (NPK) fertilizers, and the LI-farm only uses manure. Manual pruning is practiced after harvest (DecembereJanuary), and aims to reduce branch interlacing. The REFfarm applies herbicides to prevent competition among the cashew trees and other plants (weeds). The LI-farms use manual weeding only prior to harvest. Both the REF-farm and LI-farm mow between the lines of cashew trees to facilitate harvesting and promote soil covering with green manure (mulch). Insecticides, fungicides and herbicides are used only at the REFfarm, and follow integrated pest- and disease-management plans. As many as 97 species of insects and 10 types of fungus may attack cashew orchards in Brazil. However, estimates of the amount of pesticide used consider only those pests and diseases that have caused most damage to orchards during the last five years, and that have registered pesticides for this culture. The production of CN (fruit) and CA (pseudo fruit) starts in the second year, and the production of CG begins in the sixth year. CG is produced via the monthly application of growth hormone on lateral cuts made at the tree trunk. Full production (years 7e20): The adult dwarf cashew tree may be 4 m high, with a canopy diameter of 6e8 m and roots that may stomo et al., 2007). The average weight of CN achieve 12 m (Criso (kernel and shell) ranges from 7 to 12 g, and CA from 80 to 160 g. During the full production period, NPK fertilizer to stimulate CN production of 1200 kg ha1 year1; to stimulate CA production of 2160 kg ha1 year1; and to stimulate CG of 90 kg ha1 year1 is applied at the REF-farm. The LI-farm relies only on composted manure, and may produce 600 kg ha1 year1 of CN and 1080 kg ha1 year1 of CA. Annual mowing, weeding and pruning are performed, as in the low production years. At the end of the 20th year, when new cashew trees replace old ones, the CW is commercialized within the local market.
and CW). Economic allocation is applied as a default, and mass allocation to illustrate sensitivity of results with respect to the allocation principle used. The replacement of the cashew trees allows the commercialization of CW at the end of the 20th year; that is, the end of the orchard's lifetime. The harvest of CN, CA and CG over the orchard's lifetime fluctuates. Therefore, allocation considers the total production over 20 years for both mass and economic allocation. CG may start to be extracted from dwarf cashew by commercial farms in the sixth year of plant growth. High-input systems are expected to commercialize CG, whereas low-input systems are not. CG market value is assumed to be the same as that of acacia gum, which is a similar product and has long been commercialized in the world market. The allocation factors for each farm system and all products are presented in Table 1. 2.3. Description of dwarf cashew production Dwarf cashew production in the REF-farm and LI-farm encompass the following farming stages: Nursery: Cashew seedlings are produced by grafting in nursery farms. The nursery involves three steps that take 120e150 days. First, dwarf seeds are sown on compost substrates that are deposited in small polypropylene tubes (diameter of 6 cm and height of 20 cm). After 60 days of sowing, the germinated plants are grafted onto rootstocks of the scion obtained from dwarf clone gardens. The grafted plants remain in a greenhouse for 30e40 days. After this time, the seedlings are acclimatized in open fields for 30e50 days, when they are usually planted in cashew orchards. Irrigation of the seedlings occurs every day of the production cycle. Foliar fertilization takes place four times per cycle. It was considered that 60,000 seedlings of grafted cashew are produced per year within 5.6 ha, with 60 percent of seeds producing viable seedlings. Grilles measuring 20 6 4 m and made of highdensity polyethylene are used to cover the (50 percent) shaded greenhouses; these last for five years, and the polypropylene tubes last for 10. Establishment (year 1): This study assumes that a new area is converted into cashew orchards as a reference situation. Nonetheless, forested or agriculture areas may be converted to cashew orchards. Considering the sample of 10 farmers interviewed in this study, less than 10 years ago, 40% of the orchards were established in forested areas, 40%, in common cashew orchards, and 20%, in annual crop fields. As wood is not always obtained from forest and common cashew orchard conversion, it is not considered a coproduct in this study. In new areas, cashew seedlings are transplanted to soil following land conversion, plowing and harrowing. The transplantation occurs during the rainy season (January to April). Grafted cashew seedlings are planted into pits of 40 40 40 cm on sandy soils, with the pits spaced 8 6 m (208 plants ha1). Calcareous dolomite is applied at the bottom of the
Table 1 Production and earnings per hectare in the high-input (REF-farm) and low-input (LI-farm) systems, and allocation factors for the distribution of impact over the four cashew tree products. Productsa Price REF-farm LI-farm (US$ kg1) Earnings in Mass Economic Production in Earnings in Mass Economic Production in 20 years (kg ha1) 20 years (US$ ha1) allocation (%) allocation (%) 20 years (kg ha1) 20 years (US$ ha1) allocation (%) allocation (%) CN CA CG CW Total a
0.8 0.4 4.0 0.004
17,330 31,194 1260 67,392 117,176
13,864 12,478 5040 270 31,651
15 27 1 58 100
44 39 16 1 100
6433 11,579
5146 4631
8 14
51 46
67,392 85,403
270 25,117
79 100
3 100
CN: cashew nut; CA: cashew apple; CG: cashew gum; CW: cashew wood.
^do, M.C., et al., Environmental assessment of tropical perennial crops: the case of the Brazilian Please cite this article in press as: Brito de Figueire cashew, Journal of Cleaner Production (2015), http://dx.doi.org/10.1016/j.jclepro.2015.05.134
M.C. Brito de Figueir^edo et al. / Journal of Cleaner Production xxx (2015) 1e10
4
2.4. Data sources for farming inputs
3. Results
Data about the use of inputs by the REF-farm system is drawn from reports of experiments and interviews with researchers on the subject of dwarf cashew cropping systems. The experiments started in 1980 at the Embrapa Tropical Agroindustry Experimental farm, located in Pacajus, Cear a State, Brazil. Their results are re stomo et al. (2007) and Araújo (2013). ported by Criso Data about the LI-farm system is derived from interviews conducted INC, 2013 with a sample of 10 cashew farmers and two rural State, Brazil. extension agents located in six municipalities of Ceara The interviewees provided information on the average amount of input and production obtained for CN and CA during the production stages between 2010 and 2013. Inventory data for the cradle-to-gate production and transport of inputs used on cashew orchards (manure, mineral fertilizers, diesel, pesticides and plastics) is obtained from the ecoinvent 3.0 database (Weidema et al., 2013).
3.1. Inventory per production stage
2.5. Calculation of farming emissions and carbon stock in biomass The input data from Section 2.3 is used to calculate emissions and carbon stocks related to the farming process. Emissions are calculated according to IPCC (2006) and Nemecek and Schnetzer (2012). All models used for estimating these emissions, and the values applied to variables, are presented in the supplementary material. The humidity, carbon and nitrogen content of dwarf cashew trees are measured according to Silva et al. (2009) from samples of the roots, trunk, leaves and steams of a 10-year-old Clone BRS 226 tree. Samples were collected at the Embrapa Pacajus Experimental , Brazil. The biomass of the dwarf cashew tree is Station, Ceara determined by weighing the roots, trunk, leaves and steams. The biomass of common cashew trees is calculated according to Montenegro (2011), who considered a sample of 544 adult plants. The same carbon content of the dwarf cashew is used in the calculation of carbon stocked in common cashew trees. The average carbon content of the Caatinga forest is applied (savannah steppe e Ta, Tp and Tg) e that is, 14.9 t C ha1 (MCT, 2010). The common (or giant) cashew and the dwarf cashew are the species cultivated in Brazilian commercial orchards. Common cashew trees grow relatively high and have great variability in size (8e15 m) and yield ( 100 kg plant1 year1). Because of the plant size, CN from the common cashew are collected when they fall, and CA are usually damaged and left on the ground as residue, resulting in low revenues for farmers. In contrast, the usual size of dwarf cashew varieties (
