Nitrogen Flow Associated with Agricultural Practices and Environmental Risk in Japan

概要

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The excessive use of chemical fertilizers or manure in agriculture sometimes causes environmental problems, such as inland water pollution. In this study, we used a database for the estimation of the nitrogen flow associated with agricultural practices in each prefecture in Japan. We also estimated the amount of residual N in farmland and non-utilized livestock waste N, as indices of environmental risk (I.e., possibility of inland water pollution). The amount of residual N in Japan was estimated of 445, 985tN (92kg N ha^<-1>), represented the difference between the total input (1,282,824 t N; 266 kg N ha^<-1>) and total output (836,838 t N; 174 kg N ha^<-1>) in farmland. It was estimated that 71% of the residual N was associated with chemical fertilizer application. The effective use of chemical fertilizers is important for reducing residual N in Japan. Non-utilized livestock wastes were estimated to amount to 82,832 t N (17 kg N ha^<-1>). These values were higher in prefectures in which larger amounts of livestock feces were produced. Therefore, a mitigation plan for reducing environmental risk should be designed depending on the characteristics of the prefectures.
社団法人日本土壌肥料学会の論文