15N fate in maize cropping system in response to black soil fertility improvement in China

Abstract

AbstractApplications of high amounts of nitrogen (N) fertilizer are essential for obtaining sustainable maize (Zea mays L.) yields but also result in low N‐use efficiency (NUE) and cause a series of environmental problems. To optimize fertilizer management, it is necessary to determine the effects of soil fertility improvement on NUE and the fate of N fertilizer. In this study, we conducted a 15N tracer pot experiment involving five different fertilizer treatments in soils with five different total organic carbon levels under field conditions. The average NUE ranged from 36 to 56% 15N‐urea and 0.1 to 0.2% residual N in the first and second seasons. The N retained in the soil ranged from 10 to 28%, and the N lost to water and the atmosphere ranged from 29 to 39% in the five soils. Compared with that in the low‐fertility soils, NUE in the high‐fertility soils was 20–45% greater, and N loss was 1 –6% lower. The results showed that higher soil fertility corresponded to higher NUE and lower N loss. We suggest that although the local customary N fertilizer application rate (N3; 165 kg N/ha) in the study area is reasonable for low‐fertility soils, after soil fertility improvements, an approximately 50% reduction of N fertilizer should be implemented.