The Life Cycle Assessment Of Fertilization For Wheat, Maize And Rice Production In Different Regions Of China

Fertilizer, as one of the most important materials for agricultural production in China, is not only in relation to the food safety and human health, but also to the issues of the mineral resources usage, energy consumption, environmental protection and etc. Therefore, how to determine the national production of fertilizers and then use these fertilizers in a scientific way is one of the key measures to improve the efficiency of resources utilization and fulfill the sustainable development of China. Consequently, an integrative evaluation of these resources utilization and the resulted environmental impacts is urgently required in China. In this paper, inventories of resources consumption and nutrient losses were established based on the database obtained through investigating farmers'information during wheat, maize and rice production in different regions of China. Evaluation of the respective environmental impacts of fertilizations was conducted afterwards using life cycle assessment (LCA) method. Main results are as follows.(1)For wheat production, the integrative indices of environmental impacts in different ecological regions were in an order of Jiangsu (0.288), Henan (0.201) and Shaanxi (0.180). It also indicates that the integrative indices largely varied among different farmers and the variation coefficients were between 34.9% ~ 57.3%, where the greatest and least variation coefficients occurred in Shaanxi and Jiangsu provinces.While for maize production, the integrative indices of five provinces were in an order of Guangxi (0.315), Hunan (0.309), Henan (0.273), Shaanxi (0.238) and Jilin (0.183), and the variation coefficient of integrative indices among different farmers in five provinces were from 41.2% to 81.6%, where the greatest and least variation coefficients existed in Hunan and Jilin provinces. As for rice production, the integrative indices in three provinces were in an order of Guangxi's late rice (0.291), Jiangsu's single cropping of rice (0.288), Guangxi's early rice (0.270), Hunan's early rice (0.238), and Hunan's late rice production (0.221) and the variation coefficient of integrative indices among farmers were ranged from 31.8% to 50.4%, where the greatest and least variation of coefficients were found in Guangxi province's late rice production and Hunan province's early rice production. In comparison with the environmental impacts during chemical fertilizer production processes, larger environmental impact during fertilization was found. (2)Of various environmental impacts by fertilization during wheat and maize production, the order was as follows: eutrophication > acidification > global warming > land use > energy depletion. For the rice production, the order of environmental impacts was as follows: eutrophication > global warming > acidification > land use > energy depletion. This study demonstrates that the identified major environmental impacts of eutrophication and acidification were caused by ammonia volatilization during growing seasons. Provided the fertilization methods have been changed from surface broadcast to deep application, the integrated indices of fertilization can be reduced by 28.0% ~ 45.4% for wheat production, 8.5% ~ 34.1% for maize production and 31.5% ~ 36.8% for rice production.(3) With the same crop production system, Shaanxi province is associated with the smallest integrative index for wheat production, and Jilin province for maize production and Hunan province for rice production. When in the same ecological region, in Guangxi and Human provinces the integrative indices of rice production is less than maize; while in Henan and Shaanxi provinces, the maize production has a greater integrative index than wheat production; in Jiangsu province the single cropping of rice production system is with similar integrative index with wheat production. Among these three crops, the integrative index for maize production is greater than wheat and rice production.