Mixture of controlled-release and normal urea to improve nitrogen management for maize across contrasting soil types

Mixed application of controlled-release and normal urea (MCU) is considered as a promising alternative to farmers' practice with one-time nitrogen fertilization (FP) and optimal split nitrogen fertilization (OPT). In this study, MCU effectiveness on maize (Zea mays L.) were investigated by conducting 2-yr field experiments on sandy and clay soils. Across the 2 yr, grain yields in MCU increased by 22 and 18% relative to FP on sand and clay soils, respectively, and net returns increased by 65 and 19%, respectively, while total N losses reduced by 228 and 193 kg N ha(-1), respectively. In general, MCU showed significant advantages in agronomic, economic, and environmental benefits relative to FP across soil types, and the advantages were more remarkable on sandy soil. Although OPT also showed better effectiveness relative to FP, while its performances were similar to MCU on clay soil but slightly less effective on sandy soil. Compared to FP, the lower N rate and optimized N management in MCU and OPT effectively reduced N loss and ensured sufficient soil N availability to meet maize N demand at the later growth stage, accumulated more dry matter (DM) and N in plants that associated with larger post-silking ratios, and consequently improved grain yield and nitrogen recovery efficiency (REN). Our results demonstrated that MCU is an effective and promising method to concurrently meet smallholders' requirement for simplified fertilization and the optimal N management strategy, could replace OPT as an optimal N management method for maize on both two soil types, especially on sandy soil.