Changes in Chemical N, P & K Fertilizer Application Estimated from Longitudinal Survey.

We estimated chemical N, P and K fertilizer application to 7 crop groups (paddy rice, upland crop, vegetable, orchard, tea, forage, fodder) in 7 district scales in Japan from the questionnaire “Basic Soil Environment Monitoring Project, Stationary Monitoring (BSEMP-SM)” done by Ministry of Agriculture, Forestry and Fisheries, Japan. For estimation, we established the methodology with hypothesis, because BSEMP-SM data was modeled to represent the coverage of 16 soil groups on Japanese soil taxonomy and lean to full-time farms, rather than part-time farms that is dominant in Japan. The hypothesis are as follows, 1) application level would not different between full-time and part-time farms, 2) application level would not different between crop husbandry farms and livestock husbandry farms and 3) difference of application levels would larger between crop groups than within a crop group. Survey was done for 5 times from 1979 to 2003 for every 5 year period. Number of farm surveyed was more than 20,000 in 1^st to 4^th survey and more than 5,000 in 5^th survey. 5 time surveys were adopted to the year of 1980, 1985, 1990, 1995 and 2000. Estimated chemical N, P and K fertilizer was indicated as same trend as mineral N, P, K fertilizer demand (difference was -7 to +9% of demand) except for K in 2000 (30% over estimation). Application of N for paddy rice, upland crop, forage and fodder were about half of vegetable and orchard, were about 1/5 of tea that receive the highest chemical N fertilizer. We have P and K data, so will refer to P and K and also refer to difference between districts.