We estimated the release of nitrogen from coated urea in rice cultivation, using soil temperature estimated from AMeDAS (Automated Meteorological Data Acquisition System) 1-km-grid data (temperature and sunshine duration). The RMSE of soil temperature estimated at 9 points in Okayama prefecture was 0.89 ℃. Soil temperatures were easily estimated by multiple regression of data observed at 3 points to interpolate data at target sites. The estimated release of nitrogen fit measured values well, with an average difference of approximately 5% and an estimated error of the date of initial release of about 2 days. These results indicate that the release of nitrogen from coated urea can be estimated simply from AMeDAS 1-km-grid data.
