Spatial and temporal nitrogen applications for winter wheat in a loamy soil in south-eastern China

Abstract

Split application of nitrogen (N), applied by broadcasting, is both time consuming and inconvenient; yet it is widely practised for wheat. Simplified N fertilization is necessary for wheat in south-eastern China. One-time band application was compared with split application using three doses of N (150, 195, and 240 kg ha−1) in 2014/2015 and 2015/2016. Grain yield and N-use efficiency of winter wheat were determined over two consecutive seasons. A corresponding micro-plot trial using 15N-labelled urea was conducted only in 2015/2016 to measure the fate of urea-15N. The two methods showed no difference in grain yield, except at 240 kg ha−1 of N in 2014/2015. The average grain N concentration (18.2 g kg−1) was slightly lower in band application than that in broadcast application (19.2 g kg−1), but there was no significant difference (P > 0.05). In 2014/2015, N apparent recovery efficiency ranged from 33.1 to 49.9%; N agronomic efficiency, from 8.9 to 38.9 kg kg−1; and N partial factor productivity, from 23.6 to 38.4 kg kg−1. In 2015/2016, the corresponding values were 29.4–38.6%, 13.5–38.6, and 24.3–33.9 kg kg−1. In the micro-plot trial, compared to split application, fertilizer N recovery in winter wheat in one-time band application was lower by 26.5% and increased the unaccounted-N loss by 21.7%. Thus, considering environmental impacts, one-time band application of N at sowing is not a suitable alternative to broadcast application in split doses for winter wheat in the loamy soils of south-eastern China.