Synergetic effects of plastic mulching and nitrogen application rates on grain yield, nitrogen uptake and translocation of maize planted in the Loess Plateau of China

Nitrogen (N) fertilization potentially affects the amount of N uptake and N translocation (NT) within plants, but the synergetic effects of plastic mulching and N application rates on the grain yield (GY), N uptake and NT of maize have not been studied. A fertilization experiment with six N application rates (0, 80, 160, 240, 350 and 450 kg ha−1) with or without mulch was conducted in 2015 and 2016 in the Loess Plateau of China. There were significant interactions between mulch and the N fertilizer rate on the GY. Under mulch treatments, the highest GY was observed at 450 kg ha−1, which was 53.9%, 36.4%, 20.2%, 1.6% and 0.3% higher than those obtained with N application rates of 0, 80, 160, 240 and 350 kg ha−1, respectively, in 2015. The ranking of NT to grain N accumulation was leaves > sheaths and stems > ear axis > bracts. The NT efficiency (NTE) levels averaged over the different N fertilization rates under the no-mulch treatment were 5.6% and 12.9% higher than those under the plastic mulch treatment in 2015 and 2016, respectively. We conclude that an N fertilizer application rate of 240 kg ha−1 with mulch can achieve a relatively higher NTE, GY, WUE and NUE.