Effects of reducing and postponing nitrogen application on soil N supply, plant N uptake and utilization of summer maize

Field experiment was conducted to investigate effects of reducing and postponing N application on soil N supply, plant N uptake and utilization of summer maize. The results show that N accumulation rate is increased under the reducing and postponing N application (N 168 kg/ha, 1/5 basal, 3/5 topdressing at stalk enlongation stage and 1/5 topdressing at silking stage, respectively) compared with farmers' practice (N 240 kg/ha, 1/3 basal and 2/3 topdressing at booting stage, respectively), while N use efficiency, dry biomass accumulation, yield and N accumulation amount are not decreased. Moreover, the reducing and postponing N application can improve synchronization of soil N supply and crop demand during the maize growth stages, decrease NO-3-N accumulation of 0-100 cm soil profile, and reduce field apparent N loss at maturity. Therefore, the reducing and postponing N application based on summer maize N uptake at different growth stages is a feasible N management practice, and nitrogen fertilizer could be saved by 30% as compared with farmers' practice.