Abstract: The pollutants such as nitrogen (N) and phosphorus (P) caused serious pollution to the Yellow River in the process of agricultural water withdrawal. It is necessary to reduce the application amounts of N and P by further controlling the combined application levels of N and P reasonably in the process of agricultural production, thereby solving the problem of agricultural nonpoint source pollution from the source. The yield and waterfertilizer utilization efficiency of wheatmaize intercropping were analyzed under different combined applications of N and P. The yield, hundredkernel weight (or thousandkernel weight), water consumption and water utilization efficiency were increased first and then decreased with increasing the application amounts of N and P. The reasonable application of N and P significantly increased the water consumption stored in the soil and thus enhanced soil water utilization by crop. The PFP-N, PFP-P and agronomic efficiency were decreased with increasing the application amounts of N and P. The PFP-N and agronomic efficiency of crop were improved when increasing P fertilization within a certain range but keeping the application amount of N constant or vice versa. The PFP-N and agronomic efficiency of crop would be reduced when the P or N application was excessive. The best fertilization amounts of N and P which could make the maximum yield of wheatmaize intercropping were 191.70-216 kg·hm^-2 and 165.38-186.64 kg·hm^-2 for wheat, and 243-299.14 kg·hm^-2 and 168.38-189 kg·hm^-2 for maize, respectively. On the premise of guaranteeing production, the reasonable application amount of N and P could reduce fertilization and improve the waterfertilizer utilization efficiency, reducing agricultural non-point source pollution.

Key words: object-based classification, land use/ land cover,  ,  , habitat suitability index(HSI), analytic hierarchy process (AHP), entropy method (EM).