Simulation and analysis of soil water and nitrogen behaviors in Huang-Huai-Hai Plain in summer-maize growing season

The Huang-Huai-Hai Plain(HHHP) was selected as the research region of this paper. A geographic information system based conjunctive simulation model incoporating soil water, heat, nitrogen behaviors and crop growth was established and validated. The regional distributions of water and nitrogen use efficiency (WUE and NUE), and nitrogen loss were studied under the soil, meteorological and rural socio-economical condition of HHHP in 1999 by the GIS-based model. The results show that, due to the variations in biophysical conditions and farming practices, the inter-physiognomy variations on WUE, NUE as well as soil nitrogen leaching has exhibited significant differences. The multivariate stepwise regression results show that in summer-maize growing season, nitrogen leaching was significantly positively correlated with nitrogen fertilizer applied(NFA), saturated hydraulic conductivity(Ks), Active accumulated temperature(ACT), rainfall and irrigation amount(RIA). WUE was significantly positively correlated with NFA and significantly negatively correlated with ACT. NUE was significantly positively correlated with RIA and significantly negatively relative with NFA and soil organic matter(SOM).