Straw return and nitrogen fertilizer application regulate the efficient use of radiation, water, nitrogen and maize productivity in Northeast China

The combination of straw return and nitrogen (N) fertilization is an effective strategy for increasing farmland productivity and improving soil structure while mitigating climate change. However, although straw return practices are widely recommended in agroecosystems targeting sustainable agriculture, few studies have explored changes in grain yield, resource use efficiency, water productivity, and potential interactions between these variables. A field experiment was conducted during 2022–2023 in Northeast China to study the effects of straw return modes and N fertilizer input on maize grain yield and the efficient use of radiation, water, and N. We investigated two straw return tillage methods (rotary tillage with straw returning, RTS; plow tillage with straw returning, PTS) and five N fertilizer levels (0, 112, 187, 262, and 337 kg N ha−1) based on a field location experiment that started in 2015. Compared with RTS treatment, the PTS treatment resulted in a higher photosynthetic capacity by regulating the leaf area index and photosynthetic metabolism, resulting in increased dry matter accumulation and transportation. Such physiological improvements are conducive to increasing the nutrient use efficiency, water productivity, and grain yield. Specifically, PTS combined with the N3 treatment was an efficient tillage mode that increased radiation use efficiency of grain by 123.48 % and 207.41 % and by 153.44 % and 167.37 % in 2022 and 2023, respectively, compared with the PTS and N0 treatment. Together with partial least squares path modeling, regression analysis, and random forest, the variations in the above parameters led to high productivity in terms of N uptake, water productivity, leaf area index, radiation use efficiency, N use efficiency, and dry matter accumulation. Our results highlight the key roles of straw return methods in affecting grain yield, and further suggest that PTS combined with optimized N fertilizer input can enhance resource utilization, leading to a productive, efficient, and sustainable maize population.