Influence of Different Rates of N-fertilizer on Growth and N-utilization in Summer Maize

A field experiment was carried out to study the influence of nitrogen(N) fertilization on soil nitrate N(NO3-N) distribution,accumulation in soil profile,and grain yields,during the growth period of summer maize under different N application rates of 0,103.5,151.8,200.1 and 248.4 kg/hm2.The results showed that grain yields under N application was significantly higher increasing 3.7%～10.6%,than without N application,the situation reached the summit at 248.4 kg/hm2 of NFA.NO3-N in the 40 cm topsoil had a larger variation range than that in the 40～90 cm,this reached lowest value in large bell stage.During different growth periods,soil NO3-N without nitrogen fertilizer application(NFA) was less than that with NFA in 40 cm topsoil.Application N increased NO3-N content significantly.It is necessary to further study the optimal N application to get high grain yield during different growth periods.