Impacts of nitrogen practices on yield, grain quality, and nitrogen‐use efficiency of crops and soil fertility in three paddy‐upland cropping systems

BACKGROUND Global food security faces a number of challenges due to increasing population, climate change, and urbanization, while excessive use of nitrogen fertilizers has become a major challenge for sustainable, intensive agriculture. Assessing the impact of agronomic management practices on seed yield, grain quality, and soil fertility is a critical step in understanding nutrientuse efficiency. RESULT The comprehensive evaluation index had good fitness to that of single attribute (i.e. seed yield, crop quality and soil fertility), indicating that the comprehensive evaluation index was reliable. Applying controlled‐release urea (rice in wheat and oilseed rape field: 150 kg N ha−1, other crops: 120 kg N ha−1) plus common urea (30 kg N ha−1) incorporating straw from the previous season across the growing season for cereal and oilseed crops showed a slight improvement in seed productivity and Nuse efficiency among three cropping systems in the traditional evaluation method. Compared with local farm practice (applying common urea of 150 kg N ha−1), applying these practices in combination based on the outcome of the comprehensive evaluation index method decreased the seed yield by −1.27 ~ 29.8% but improved quality and soil fertility for the paddy‐upland cropping system, respectively. CONCLUSION Properly managing N application by applying partial and fully controlled release of urea with or without straw incorporation for a specific crop system has the potential to provide a better compromise among yield, grain quality, and soil fertility in southern China. © 2020 Society of Chemical Industry