[Strategy of grain yield stability cooperated with harmonious water environment quality of small agricultural watershed].

This paper investigated the spatial variability of the correlations between grain yields and fertilization quantity within the selected agricultural watershed, in the typical black soil region, and then optimized the fertilization quantity at different landscape farmlands within the watershed based on the regression equations. Study simulated the surface runoff water quality before and after fertilization spatial adjustment with the achieved parameters by Soil and Water Assessment Tool (SWAT) model. The results showed that watershed scale fertilization adjustment is possible and necessary according to the spatial heterogeneity about fertilization and grain yields. Based on grain yield stability, spatial adjustment of fertilization reduced the whole watershed total N fertilization quantity by 1.88%, and the total non-point nutrients load reduction of NH4+ -N and NO3- -N was 9.7%, 5.6%, respectively.