Effects of integrated fertilizer application on nitrogen use efficiency of spring maize and soil nitrogen content on black soil in Harbin

With the increase in planting area of spring maize and nitrogen (N) application in Heilongjiang province, the high potential of N pollution to the environment and resource waste should be given urgent attention. In this study, N use efficiency (NUE), grain harvest index and partial factor productivity of nitrogen were calculated to evaluate the balance between N application, grain yield and soil N content based on a 3-year plot experiment with different N application. The results showed that high N application did not result in high NUE, rather it decreased, and that low N application with high NUE led to soil N deficit. Considering N surplus and NUE in spring maize production, the primary conclusion could be drawn that 180 kg N ha(-1) are acceptable both for grain yield and N risk to environment for spring maize in Harbin area.