Optimization of controlled-release urea application based on the winter wheat yield

Wheat is of great significance to ensuring national food security in China. The one-time fertilization for saving labor was common in winter wheat production in the North China Plain, which caused the excessive application of nitrogen (N) fertilizer generally. Controlled-release urea (CRU) has a good application effect in crops with short growth periods such as rice and maize. However, the applications of CRU on winter wheat with a longer growth period are fewer. To investigate the appropriate dosage and blending proportion of CRU and urea in wheat production, the field experiment with 52 treatments was conducted in 2019–2021. This relationship among N application rates, CRU release longevity, CRU proportions and winter wheat yield was systematically studied, and the binary quadratic effect models between yield and CRU factors were established. N application rates, CRU proportion and the interacted effect of CRU proportion and release longevity had the greatest effect on winter wheat yield by the main effects test and correlation analysis. The winter wheat yield could be accurately predicted by CRU proportions and CRU release longevity. The prediction errors of yield models were −9.8%∼4.9% based on the 2018 and 2022 two years winter wheat yield with CRUs application. Reducing N application rates by 20∼30% and mixing with appropriate CRU proportion would increase the yield and NUEs (nitrogen use efficiencies) of winter wheat. In the case of low CRU proportion, the wheat yield could be increased by applying the CRU with long-release longevity; when the CRU proportion was high, the yield increase effect of the CRU with short-release longevity was better. Comprehensive field production survey and Response surface methodology (RSM) partial derivative analysis, CRUs with controlled release longevity of 57d∼150d and CRU proportion of 24∼64% were the best choices for increasing wheat yield and reducing N application rates. It will facilitate the optimization of wheat CRU manufacture and application and promote the 'Reduction and Efficiency of Chemical Fertilizers' policies and environmental protection.