Maize yield increased by matching canopy light and nitrogen distribution via controlled-release urea /urea adjustment

Rational fertilization can optimize canopy structure, uniformly distribute light and nitrogen, improve photosynthetic characteristics, and accumulate dry matter to improve maize yield. However, the basic physiological and agronomic mechanisms of action of the combination controlled-release urea + urea (CCU) remains unknown. The objective of our study is to examine the spatial distribution of nitrogen and light within maize canopies in order to optimize future maize yields. In the 2021 and 2022 growing seasons, a two-year field experiment was conducted to assess the performance of two maize varieties: ZD958 (green maturity) and JNK728 (yellow maturity). Five fertilizer treatments were applied, including CK (zero N); N180U (180 kg N ha−1, all Urea-N); N180C1 (180 kg N ha−1, CRU-N: Urea-N = 1:2); N180C2 (180 kg N ha−1, CRU-N: Urea-N = 2:1); and N180C (180 kg N ha−1, all CRU-N). Multivariate characteristics of canopy leaves, canopy light conditions, and nitrogen distribution were measured. Grain yield was simulated using a hybrid maize model based on crop management practices and climate interactions. Maize treated with CCU also intercepted more radiation through adjustment of leaf area; there was a significantly increase in the content of nitrogen in the leaves, and the coordination between nitrogen and light distribution in the canopy was significantly improved by the CCU treatments, all of which contributed to the plant maximum utilization of solar radiation. The CCU optimized the canopy distribution of nitrogen and light and improved shoot biomass, which improved grain yield. Significant increases in yield were observed in the N180C2 treatment of ZD958 and N180C1 treatment of JNK728, compared to N180U. A suitable CCU applied to the right varieties (N180C2 treatment of ZD958 and N180C1 treatment of JNK728) could optimize canopy structure and increase grain yield in maize systems. This experiment provides a new idea for maize intensive production and reducing environmental pollution and other aspects of nitrogen management in some areas the North China Plain.