Meta-analysis of management-induced changes in nitrogen use efficiency of winter wheat in the North China Plain

Increasing nitrogen use efficiency by optimizing field management practices is necessary to promote intensive and sustainable development of winter wheat production. The objective of this study was to comprehensively assess the changes of nitrogen use efficiency induced by field management practices, and to identify the suitable combination of strategies for winter wheat management in the North China Plain. For this, a meta-analysis was conducted with 977 comparisons from 106 publications. The results showed that the nitrogen partial factor productivity of winter wheat is inconsistent in response to different agricultural practices. Nitrogen input and irrigation significantly increased the nitrogen partial factor productivity by 132.75% and 24.01% (P < 0.05), respectively. However, the change of the nitrogen partial factor productivity was not significant under different tillage practices or straw return. Nitrogen application rate, irrigation times, seasonal precipitation, and soil bulk density significantly affected the responses of the nitrogen partial factor productivity induced by management practices. In the nitrogen input or water irrigation treatments, the total water consumption of the winter wheat improved with the increase of the nitrogen partial factor productivity within a certain range. Theoretically, optimal nitrogen partial factor productivity could be obtained for winter wheat in the North China Plain under two different conditions: (1) optimum water with less nitrogen, experimental duration <3 years, nitrogen application <150 kg N ha(-1), irrigation amount plus precipitation >240 mm, one irrigation or (2) optimum nitrogen with less water, nitrogen application 150-180 kg N ha(-1), irrigation amount 80-160 mm, two irrigations. Both of these conditions could enhance the nitrogen use efficiency of winter wheat. According to our study, the pursuit of optimized field management practices must include a closer evaluation of the changes in nitrogen use efficiency, as well as other nutrients. (C) 2019 Elsevier Ltd. All rights reserved.