| According to the disordered planting structre,nitrogen application system backward of cereal//legume intercropping in Hexi oasis irrigation area. Take maize//pea intercropping as representative. A field experiment was carried out to investigate the effects of different nitrogen application and planting structure on fertilizer and water use efficiency of maize//pea intercropping, explores and analyse the basic mechanism of this model efficient utilization. The main results showed as following:1. Land utilization efficiency and crop yield were significantly increased in maize/pea intercropping. Three rows of maize intercropped with four rows of pea (3:4) was more beneficial to increase LER; The LER and yield of intercropping increased with the increase of nitrogen application, but the increase of intercropping was weaken when nitrogen application beyond a certain level. The LER of two rows maize: four rows pea intercropping(2:4) was 1.08, 1.43, 1.46 at no nitrogen application, reduce 15%, habit nitrogen application respectively, and the LER of 3:4 planting pattern at 3 nitrogen applications was 1.07, 1.5, 1.56 respectively. The LER of 3:4 intercropping was increased by -0.93%, 4.9%, 6.85% than 2:4 intercropping at 3 nitrogen applications. The yield of habit nitrogen application under 2:4, 3:4 intercropping were increased by 47.48%, 0.18% and 50.19%, 0.46% than no nitrogen application,reduce 15% treatment.2. WUE of maize/pea intercropping was significantly increased. Intercropping of 3:4 was more beneficial to increase WUE, the WUEer of intercropping increase as the increase of nitrogen application, there was no significant difference between habit nitrogen application and reduce 15%. The WUEer of 2:4 intercropping at no nitrogen,reduce15%,habit nitrogen application were 1.14, 1.48, 1.56, and the WUEer of 3:4 intercropping at 3 nitrogen application was 1.08, 1.53, 2.02 respectively. WUEer of 3:4 intercropping higher than 2:4 intercropping -5.26%,3.38%,29.49% at 3 nitrogen application. The WUE of habit nitrogen application under 2:4,3:4 intercropping was increased by 103.66%,1.74% and 118.21%,6.28% than no nitrogen application,reduce 15% treatment,respectively. Maize and pea intercropping increase nitrogen use efficiency significantly. Compared to weighted average nitrogen use efficiency of sole cropping,, 2:4 and 3:4 at no nitrogen application,reduce 15%,habit nitrogen application was increased by 80.06%,65.61% and 96.69%,74.05% respectively. Nitrogen use efficiency of 3:4 at reduce 15%,habit nitrogen application was increased by 14.81%,11.24% than 2:4 intercropping, showed that nitrogen use efficiency of 3:4 intercropping could increase was higher than 2:4 intercropping. compared to reduce 15%,nitrogen use of efficiency of 2:4 Habit nitrogen application was reduced by 6.42%, nitrogen use of efficiency of 3:4 reduce 9.83%, showed that habit nitrogen application reduce 15% was help to increase nitrogen use of efficiency.3.The main reason of improving WUE in maize//pea intercropping were that the economic yield and nitrogen use of efficiency increased withthe increase of LAI-D and whole growth stage rainfall; At no nitrogen application,reduce 15%,habit nitrogen application, LAI-D of 2:4 intercropping was increased by 28.55%,20.29%,41.33%, LAI-D of 3:4 intercropping was increase by 52.72%,44.46%,44.68%, the difference between intercropping and sole was significant. Compared to sole pea, whole growth stage rainfall of pea maize intercropping was increased by 73.2% which increased the yield of crops. The average crop growth period soil water content of 2:4 intercropping was increased by 1.57%,4.18%,1.54%, and 3:4 intercropping was increased by 0.28%,14.85%,11.11% than weighted average of sole cropping, respectively .
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