Adaptation of life cycle assessment (LCA) to agricultural production on a regional scale in Japan

Transcription

1 Ecosystems and Sustainable Development V 671 Adaptation of life cycle assessment (LCA) to agricultural production on a regional scale in Japan S. Mishima, S. Taniguchi & M. Komada National Institute for Agro-Environmental Sciences, Japan Abstract LCA was applied to paddy rice farming with a relatively low livestock production area on a mid-river basin scale in Japan. Conventional farming, standard application of chemical fertilizer and manure, and low chemical fertilizer input and forage production scenarios were tested. The aquatic eutrophication potential and the global warming potential per unit of crude protein production were lower for low chemical fertilizer input and forage production than for conventional farming, although terrestrial eutrophication was not reduced. These results indicated that reduced input would be effective in areas with contamination of ground and surface water and regulation of nutrient input would be reasonable. Abiotic resource use was also lower for low chemical fertilizer input and forage production than for conventional farming. Recycling of livestock excreta would be viable in non-intensive livestock production areas. Keywords: agriculture, fertilizer, life cycle assessment, livestock, region. 1 Introduction Life cycle assessment (LCA) is a method that integrates various environmental impacts at each production step into simple indices to indicate what and where are the hot spots of environmental load on production. Brentrup et al. [1] devised theoretical steps to adapt agricultural production to LCA and evaluated environmental impact on wheat and beet production [2, 3]. Despite several trial calculations for effective nitrogen (N) management for low impact agriculture at regional and river basin scales [4, 5], LCA has not been applied to these scales. In this study, we tried to apply the LCA method to agriculture to a mid-scale

2 672 Ecosystems and Sustainable Development V river basin and evaluate how recommended practice would reduce environmental impacts caused by N and phosphate (P2O5) deriving from fertilizer and feed use. 2 Methods 2.1 Site description and data source We chose the Omoigawa river basin in Tochigi prefecture in Japan as a typical paddy rice farming area. For data availability, old 36 districts were selected as the basin that could identify the shape of basin. An overview of this river basin and agricultural statistics are shown in Table 1 and compared with the Japanese average. These data were taken up from 2000 Agricultural Census [6] and agricultural statistics [7]. Table 1: Basic statistics of Omoigawa basin. Area (ha) Occupation Japanese average Total area 92,800 Total farmland 19, % 100.0% Total planted area 16, % 88.9% Paddy field 11, % 39.3% Upland field 4, % 23.4% Orchard % 7.0% Forage % 19.2% No cultivation 3, % 11.1% Livestock Head number Density (head ha -1 ) (Japanese average) Daily cattle 5, Beef cattle 14, Pig 37, Layer 1, Broilar 2, Goal and scope definition We defined the goal and scope of this analysis as estimation of environmental impacts caused by N and P2O5 use on crop and livestock production in a midscale river basin and estimation how environmental impacts will be reduced by different management practices. The crop and livestock management systems were analyzed under conventional farming (CONV), standard farming (STD) and low input and forage production farming (LIFP). On CONV, chemical N and P2O5 fertilizers and manure use was according to the results of a questionnaire administrated by

3 Ecosystems and Sustainable Development V 673 the Ministry of Agriculture, Forestry and Fisheries (MAFF) in 1998 and Tochigi prefecture. On STD, chemical fertilizer was applied according to the prefecture's recommendations [8]. Manure application to each kind of farmland was according to Shiga [9]. On low input and forage production (LIFP), chemical fertilizer application was reduced by slow release fertilizer [10]. Some of the chemical fertilizer for paddy rice was replaced with chicken manure [11], While some part of purchased forage from outside was self-stuffed on non-cultivated farmland by recommended amount of manure, urine and chemical fertilizer. The system boundary was set as shown in Figure 1 to encompass the Omoigawa river basin geographically. A recycling pathway was included in this system as an original framework. Abiotic resource use accompanying fertilizer use and forage production and emissions from each process are also indicated in Figure 1. Abiotic resource NH3, N2O, NO, Surplus Oil Ore Raw material Production Consumption Chemical fertilizer Farmland Crop product Manure Forage Chemical fertilizer Forage Livestock Animal product System boundary NH3, N2O, Residual excreta Figure 1: Framework of this study. Farmland N and P 2O5 surplus N2O emission NO emission Livestock Residual excreta NH3 emission N2O emission Chemical fertilizer N fertilizer P2O5 fertilizer Feed N in feed N fertilizer P2O5 in feed P 2O5 fertilizer Eutrofication Terrestrial Aquatic Acidification Global warming Abiotic resource Figure 2: Impact categories.

4 674 Ecosystems and Sustainable Development V 2.3 Life cycle inventory and life cycle impact assessment Abiotic resource use and impacts on the environment in each process are shown in Figure 2. Emission factors for each process were based on past studies [12, 13, 14, 15, 16]. Normalization values that aggregate various impacts into simple ones were according Brentrup et al [1]. Crude protein (CP) was set as the functional unit, because protein is contained in all crops and livestock products and is considered to be an important nutrient. 3 Results and discussions 3.1 Lifecycle inventories Crop production was the highest on LIFP, because of the increase of forage production from non-cultivated farmland (Table 2). Chemical fertilizer use was reduced >30% on STD compared with CONV (Table 2). The largest contributors were paddy and upland fields where chemical fertilizer input was reduced to 25-50% of CONV. Input on CONV would be too large in these fields. However, the difference between STD and LIFP was small. This would indicate that the recommended application level is low enough and a little margin to reduce the fertilizer. The surpluses of N and P2O5 that indicated by chemical fertilizer and manure and natural (N2-fixation, irrigation) input minus crop production, N2O and NO emission and natural output (denitrification) were the lowest for STD, because of the low input of manure (Table 3). On LIFP, high input to forage production contributed to a higher surplus than STD. Table 2: Nutrient balance sheet of crop production. Scenario Chemical Manure Product Natural N2O NO Surplus fertilizer in and out*emissionemission CONV N 1, , ,147 P2O5 2, ,728 STD N 1, , P2O5 1, ,041 LIFP N 1,142 1,073 1, P2O5 1, ,118 Unit : Mg *:Aggrigated value of irrigation, N2-fixation and denitrification. 3.2 Feed consumption, livestock manure use and dispose Although this study area was not an intensive livestock production area, the amount of feed consumption N was larger than chemical fertilizer N and feed was mostly imported from outside of the study area. Only 1/4 to 1/3 of nutrients were utilized as products except poultry, therefore livestock excreta would have significant effect for environmental load (Table 3) and it can be said the excreta

5 Ecosystems and Sustainable Development V 675 came from outside of study area. About 40% of the excreta N volatilized as NH3 and N2O during the composting and storage of dung and urine. More than half of the excreta was utilized and the other was disposed (Table 4). While this condition would be improved under STD that aimed to maintain soil fertility, forage production (LIFP) was needed to consume all livestock excreta (Table 4). Table 3: Nutrient balance sheet of livestock production. Feed Product Excreta Manure Emission Dung Urine NH3 N2O Bovine N 1, P2O Swaine N P2O Poultry N P2O Unit : Mg Table 4: Fate of livestock excreta. 3.3 Abiotic resource use Abiotic resource use was reduced in STD and LIFP in conjunction with reduction of chemical fertilizer use and recycling of manure as fertilizer (Table 5) without reduce crop production (Table 2).

6 676 Ecosystems and Sustainable Development V Table 5: Abiotic resource use. Table 6: Environmental impacts by agricultural production. Impacts Unit CONV STD LIFP Aquatic eutrophication potential Mg PO4eq Terrestrial eutoriphication Mg NOxeq Acidification Mg SO2eq Global warming potential Mg CO2eq Abiotic resource use - 257, , ,760 Function unit Mg CP 10,317 10,317 10,317 Normalized value Aquatic eutrophication potential kg Mg Terrestrial eutoriphication g Mg Acidification g Mg Global warming potential g Mg Abiotic resource use Mg Aquatic eutrophicatio potential 100(%) 75 Abiotic resource Use Terrestrial eutrophication CONV STD LIFP Global warming Acidification Figure 3: Relative environmental impact. (CONV was set as 100%.)

7 Ecosystems and Sustainable Development V Environmental impacts Environmental impacts (aggregation of each emission and resource use with characterization factor) were indicated in Table 6. Environmental impacts were the highest in CONV and the lowest in LIFP and LIFP was the lowest in all impacts. This indicates LIFP was the best management practices for this study area. However, the degree of reduction was different for each impact (Fig. 3). The rate of reduction of aquatic eutrophication potential, global warming and abiotic resource use were relatively larger than terrestrial eutrophication and acidification. 4 Conclusion In this study, weighting was not done, because our purpose was to evaluate the degree of reduction of environmental load by different management practices. Mishima [5] indicated that residual N could be reduced by low input of chemical fertilizer and recycling of livestock excreta. This study indicated that P2O5 could also be reduced. Reduction of N and P2O5 input would reduce eutrophication and global warming that are important impacts from agro-environment. This study showed that these impacts could be reduced easily by changing fertilizer application. Recently, local governments have recommend low inputs of chemical fertilizers, especially for paddy rice, and have attempted to shift production techniques from CONV to STD. Limiting chemical fertilizer and manure application could be reasonable actions in water-contaminated areas, although it might be difficult to feel low contribution to global warming. However, this area has enough abundant farmland that could be converted to forage fields with a higher capacity to utilize and recycle manure and urine. These factors are capable of mitigating environmental impacts. The reduction of abiotic resource use has advantages in low input and forage production. However, these techniques are only effective in low livestock production areas. Mishima [17] indicated there might be no mitigation method for heavy livestock production areas. LCA should be done in such areas to formulate better management practices. References [1] Brentrup F., Küsters, J., Kuhlmann H., & Lammel J. Environmental impact assessment of agricultural production systems using the life cycle assessment methodology: I. Theoretical concept of a LCA method tailored to crop production. European Journal of Agronomy, 20(3), pp , 2004 [2] Brentrup, F. Kusters, J. Kuhlmann, H. & Lammel, J. Application of life cycle assessment methodology to agricultural production: an example of sugar beet production with different forms of nitrogen fertilizers. European Journal or Agronomy. 14 pp , 2001

8 678 Ecosystems and Sustainable Development V [3] Brentrup, F. and Kusters, J. Lammel, J., Barracluough, P. & Kuhlmann, H. Environmental impact assessment of agricultural production systems using the life cycle assessment (LCA) methodology II. The application to N fertilizer use in winter wheat production systems. European Journal of Agronomy. 20, pp , 2004 [4] Zebarth, B.J., Hii, B., Leibscher, H. Chipperfield, K. Paul, J.W. Grove, G. and Szeto, S.Y. Agricultural land use practices and nitrate contamination in the Abbotsford aquifer, British Columbia, Canada. Agriculture, Ecosystems and Environment. 69, pp , 1998 [5] Mishima, S. Recent trend of nitrogen flow associated with agricultural production in Japan. Soil Science and Plant Nutrition. 47(1), pp , 2001 [6] Ministry of Agriculture, Forestry and Fisheries (MAFF) (eds.) Agricultural Census 2000, MAFF: Tokyo, [7] MAFF The 77th Statistical Yearbook of MAFF Japan , MAFF: Tokyo, 2002 [8] Tochigi prefecture Fertilization Standard, Tochigi prefecture: Utsunomiya, pp. 5-60, 2004 [9] Shiga, H., Capacity of organic resources application to farmland and livestock wastes, Research centre for daily farming: Sapporo, pp , [10] Ibaraki prefecture, Guideline for sustainable agricultural production, Ibaraki prefecture: Mito, pp. 95, [11] Iwate prefecture, Report of advanced utilization farming method of livestock feces, Iwate prefecture: Morioka, pp , [12] Kobayashi, H. & Sato, R. A study on life cycle assessment of energy consumption and CO2 emissions in the manufacturing and transportation processes of nitrogen and phosphate fertilizers. Japanese Journal of Farm Work Research. 36(3), pp , 2001 [13] Akiyama, H., Tsuruta, H. & Watanabe, T. N2Oand NO emissions from soils after the application of different chemical fertilizers. Chemosphere, 2, pp , 2000 [14] Yasuo, H., Quality of livestock excreta (Chapter 8) Livestock Production Part, Encyclopedia of Agricultural Technologies, ed Nosangyosonnbunka Association, Nosangyosonnbunka Association: Tokyo, pp.1-6, 1999 [15] Japan Soil Association, Report about global warming gas emission from soil, Tokyo, pp. 24,1995. [16] Haga, K. & Waki, M., LCA of composting method of beef cattle, Norinsuisan Research Journal, 22(10), pp , 1999 [17] Mishima, S. Quantitative evaluation of environmental risk associated with nitrogen flow in agricultural production and mitigation plan for 2 typical prefectures in Japan, Soil Science and Plan Nutrition, 47(3), pp , 2001.