Abstract: 【Objective】This study was conducted to evaluate the adequacy of nitrogenous fertilizer application and to provide scientific references for nitrogen management.【Method】At the basis of the soil mineralization model, organic manures nitrogen releasing model and nitrogenous fertilizer use efficiency model, the models combined with GIS was applied to analyse the spatial variability of nitrogen nutrition from soil and organic manures and its contributing factors in 2000，Jiangsu province. Then the model simulation cropland requirement nitrogenous fertilize was compared with the actual nitrogenous fertilizer application to evaluate its adequacy.【Result】There was about 71.8% cropland overmuch of nitrogen when calculated by actual crop yield, the total quantity was 760 kiloton, accounted for 41.5% of all nitrogen application. While calculated by actual tiptop yield, there was 64.3% cropland short of nitrogen, the total quantity was about 800 kiloton. Nitrogenous fertilizer was used in very low efficiency in Taihu lake area, Nanjing-Zhenjiang hilly area and Xuzhou area, while the deficient nitrogenous fertilizer region mostly distributed at east beach area.【Conclusion】It was great advantageous for transferring superfluous nitrogenous fertilizer from excessive application area to lower area.

Key words: nitrogen application, adequacy, model, GIS