Legislation represented by the Livestock Waste Disposal Law and Compost Quality Control Law were enacted in order to reduce the excessive use of chemical fertilizer and disposal of untreated livestock waste. These laws encourage the replacement of chemical fertilizer use with livestock waste compost. The potential supply of nitrogen (N), phosphorus (P2O5) and potassium (K2O) from compost was estimated using computer software and prefectural and municipal data from the 2000 Census of Agriculture in Japan. Use of N, P2O5 and K2O as chemical fertilizer in Japan was also estimated by the questionnaire data by the Ministry of Agriculture Forestry and Fisheries and the 2000 Census of Agriculture. The percent of chemical fertilizer replaceable with livestock waste compost was calculated by dividing the supply from compost by the use of chemical fertilizer on the basis of N, P2O5 and K2O. Average and range of replaceable percent was 20.4% (106.9-7.1%), 21.8% (105.3-7.0%) and 31.5% (124.1-7.6%) in N, P2O5 and K2O, respectively, among the 47 prefectures. The range in about 3,300 municipalities fluctuated between 2,047-0%, 3,762-0%, and 3,207-0% in N, P2O5, and K2O, respectively. The significance of the data is discussed in the text.
