Quantitative evaluation of the possibility of the strategy for sustainable food system by unutilized organic fertilizer resource

Abstract

This study was conducted to estimate the amount of nitrogen (N), phosphorus (P), and potassium (K) in chemical fertilizer application, food refuse compost, and sewage sludge compost for analyzing the reality concerning the Strategy for Sustainable Food System, Japan. The year 2020 was set as the target year and the national and prefecture scales were used for evaluation. The scenarios for evaluation were as follows: 30％ of chemical NPK fertilizer was supplemented by sewage sludge and food refuse composts for 30％ reduction of chemical fertilizer, and 25％ of chemical NPK fertilizer was supplemented by food refuse compost for organic agriculture. In both scenarios, this study focused on nutrient efficiency for composts against chemical fertilizer. Tokyo, Osaka, and Kanagawa would stuff 30％ of chemical NPK fertilizer by sewage sludge and food refuse composts, but not Hokkaido, Akita, and Aomori. The other prefectures lacked N, P, and/or K chemical fertilizer. On the national scale, P and K in food refuse compost can substitute 25％ of chemical P and K fertilizer. The amount of N in food refuse compost was insufficient to substitute 25％ of chemical N fertilizer. Tokyo, Osaka, Kanagawa, and 18 prefectures could stuff 25％ of chemical NPK fertilizer by food refuse compost, whereas the other 26 prefectures could not. Hokkaido, Aomori, Yamagata, and other 7 prefectures lacked NPK, and the other 16 prefectures lacked N and/or K. The possibility of 30％ reduction of chemical fertilizer and organic agriculture by 25％ of planted area on prefecture scales would be dependent on their situations, namely, population, sewage population, planted area, types of planted crops, and chemical fertilizer application. Although the Strategy for Sustainable Food System could be possible on the national scale, adaptation for all 47 prefectures remains uncertain. Regional adoptive plannings with consideration of local fertilizer resources must achieve the Strategy for Sustainable Food System as possible on prefecture scales.