The Effect of Crop Residue Management and Nitrogen Supply on Canopy Light Interception and N Distribution

Nitrogen (N) combined with crop residue retention offers an effective way to achieve soil sustainability. To achieve better results, crop residue is generally incorporated into the soil. However, there is limited research on residue management and N application impact on the vertical distribution of the crop canopy and N allocation. This study used a long-term field experiment that commenced in 2011 as a research platform to uncover the relevant mechanisms of optimized combination of crop residue management and N input increased yield and grain nitrogen use efficiency (NUE). Sampling was conducted in 2021 and 2022 on the maize hybrid Fumin 985 to analyze the canopy distribution and N allocation under two crop residue management strategies and five N application rates. The two residue management treatments were no tillage with straw mulch (SM) and plow tillage with straw mulch (SP). The five nitrogen application rates were 0 kg N ha −1 (N0), 90 kg N ha −1 (N90), 150 kg N ha −1 (N150), 210 kg N ha −1 (N210) and 270 kg N ha −1 (N270). The study results indicated that SP achieved the same or better maize yield as SM but with lower nitrogen input. SP yield was 17.54% greater than SM with less than 150 kg N ha −1 . SP significantly improved the proportion of grain dry weight and led to an increase of 12.43% in 1000-grain weight compared to SM. Furthermore, SP maintained a higher leaf area index (LAI) and total radiation interception rate (RIR) during the grain-filling stage with the same N application rate as SM, increasing post–tasselling dry matter accumulation. Additionally, SP reduced soil bulk density and moisture content before sowing, increasing soil temperature. SP increased the grain's relative N content, which improved nitrogen uptake efficiency (NUpE) and NUE. Finally, SP demonstrated a synergistic enhancement in yield and NUE under lower N application rates than SM. In summary, the combination of SP with 150 kg N ha −1 quantified it as an effective method to achieve greater yield and improved efficiency in maize production compared to SM. These findings are instrumental in formulating appropriate residue management and determining optimal nitrogen fertilizer application rates, thus providing a viable pathway for sustainable agriculture. However, it is essential to consider field specific conditions and farming context in determining optimal crop residue management and N application rates.