Effect of controlled-release urea combined application with urea on nitrogen utilization efficiency of winter wheat

In rich fields, with the rising of application rate of nitrogen fertilizer, both the utilization efficiency and unit production rate of nitrogen fertilizer declined. The loss of N not only waste the fertilizer but also bring about a high potential risk of environmental pollution. Aiming to increase the crop production and N utilization, a field plot experiment was conducted to study the effects of combination application of conventional urea with controlled-release urea on grain yield, grain protein content, nitrogen utilization efficiency of winter wheat and accumulation of NO3--N in soil. The results showed that combination applications of conventional urea with controlled-release urea, no matter was the N rate equivalent to or 30% less than that of single conventional N, could increase grain yield significantly and raised grain protein content markedly or maintain same in comparison with single application of conventional urea. Meanwhile, nitrogen utilization efficiency was improved and accumulation of NO3--N in soil was reduced markedly.