[Optimum nitrogen application rate to maximum yield and environment protection for winter wheat in Weibei dryland,...

To get the optimum nitrogen (N) fertilization rate which could guarantee wheat yield and protect environment, we examined wheat yield, N use efficiency, apparent N loss and soil N balance in Weibei dryland with a 3-year field experiment. The results showed that annual wheat yield increased and then decreased as N application rate increased in all the years with different annual rainfall, but the cumulative apparent N use efficiency significantly decreased. Higher yield and N use efficiency were obtained at the fertilization rate of 150 kg·hm^-2. Residual nitrate-N concentrations significantly increased with the increases of N application rate. When the N application rate was between 75 and 150 kg·hm^-2, the apparent N loss and loss rate were nearly the same, but if N application rate was higher than 150 kg·hm^-2, the apparent loss and loss rate significantly increased. In conclusion, N application rate at 150 kg·hm^-2 in Weibei dryland could guarantee high yield and N use efficiency, and simultaneously maintain residual nitrate-N concentration and reduce apparent N loss.