Maize Yield Response to Nitrogen Rate and Plant Density under Film Mulching

Film mulching has significantly improved crop productivity in semiarid areas. We hypothesized that plants grown under the film-mulched system (FM) require higher N rates and higher plant densities than the non-mulched system (NM) to optimize grain yield and water use efficiency (WUE). A 2-yr field experiment was conducted at the Changwu experimental station to evaluate the effects of N supply and plant density on grain yield, yield components, evapotranspiration, and WUE in spring maize (Zea mays L.) with and without film mulching. Results showed that FM improved topsoil water content. Mulch practice x N rate and mulch practice x plant density interactions existed for yield and WUE in both years. Regression analysis showed that yield and WUE increased with increasing N rate and plant density for FM. The predicted maximum yield (14.3 and 15.1 Mg ha(-1) in 2013 and 2014, respectively) and WUE (31.3 and 38.4 kg ha(-1) mm(-1) in 2013 and 2014, respectively) for FM were obtained at 280 kg N ha(-1) and 80,000 plants ha(-1). Lower N amounts and lower plant densities were required for NM to obtain the maximum yield and WUE. However, field experiments showed that the N amount of 225 kg ha(-1) in FM increased N use efficiency while yielding > 94% of the maximum. In conclusion, film mulching together with optimum N application rates and plant densities can improve maize production and WUE in semiarid regions.