Effect of split application of nitrogen on nitrous oxide emissions from plastic mulching maize in the semiarid Loess Plateau

Applying nitrogen (N) using split application to improve temporal synchronicity between crop-N demand and soil-N availability is a key strategy for improving nitrogen use efficiency (NUE). Its effect on nitrous oxide (N2O) emissions has not been well evaluated, especially from plastic mulching maize (Zea mays L.) in semiarid farmland. We conducted a two-year experiment to investigate the effect of split fertilizer N application on N2O emissions. Three approaches each applying a total of 225 kg N ha(-1) were tested either as a single application at sowing (N1), N applied with two splits at a ratio of 4:6 (N2), and N applied with three splits at a ratio of 4:3:3 (N3), a no-N application treatment was also included as a control (NO). Compared with the single application, split application of N significantly increased the grain yields by 4.7-9.1%. The cumulative N2O emissions significantly increased by 18.1% under the three splits application in the 2014-2015 season compared with the single application but not in the growing season of 2015, which followed the same pattern with yield-scaled N2O emissions. Fertilizer application combined with precipitation was the main driving factor for N2O emissions. Therefore, the higher frequency (three times) of fertilizer application had a high risk for increasing N2O emissions due to the relatively strong and frequent precipitation in maize mid and late growth period in this region; applying N with two splits is more suitable for this region which could produce higher grain yields, and lower risk of N2O emissions. (C) 2015 Elsevier B.V. All rights reserved.