The Effect of Water-nitrogen Regimes on the Nitrogen Utilization and Soil NO_3~-—N Residue of Winter Wheat-summer Maize System in the North China Plain

Over-input of water and nitrogen is a common problem of the winter wheat-summer maize system in the North China Plain,thus a field experiment was conducted to analysis the yield,nitrogen utilization and soil NO3——N residue of this system after reduced resource input in Wuqiao of Hebei province in 2008-2010.Four treatments were included: Conventional input,Conventional input(Improvement),Reduced input and Least input respectively.Compared with Conventional input pattern,N fertilization input decreased 55% and water input decreased by 36.6% of Reduced input pattern,while there was no significant difference on the yield between two patterns.Under Reduced input pattern,the PFP was 60.17 kg/kg,soil NO3——N residue was only 99.3 kg/ha in the 2 m soil profile.Under Least input pattern,the annual yield declined 13%,but nitrogen partial factor productivity was 1.78 kg/kg,soil NO3——N residue was only 42.8 kg/ha in the 2 m soil profile.In conclusion,reduced input pattern with fertilization amount of 270 N kg /ha was applied in annually and irrigation at blooming and jointing stage in winter wheat season,could assure the yield of winter wheat-summer maize rotation system,and simultaneously improve nitrogen use efficiency and reduce soil NO3——N residue.