Soil fertility differences due to tillage methods modulate maize yield formation at different planting densities.

To address the problems of planting density and low soil nutrient content in maize cultivation and production in western Inner Mongolia. This study aims to elucidate the regulatory mechanism by which soil fertility augmentation affects maize yield formation under a variety of planting densities. In this study, nine soil fertility conditions were established by deep tillage, no-tillage and in situ straw return. Utilizing Xianyu 696 as the experimental subject, this study documents variations in the parameters of maize grain filling rate and yield components under differing planting densities. Enhancement of soil fertility can modify diverse parameters of maize grain filling characteristics, effectively undermining the adverse impact of a lower average filling rate on grain weight post-densification. The enhancement in soil fertility predominantly augments the grain weight by prolonging the active grain-filling period. This results in a reduced decline in final grain growth during densification under conditions of high soil fertility. The improvement of soil fertility significantly enhances the harvested number of panicles, the number of grains per panicle, and the 100-grain weight of maize, consequently increasing the maize yield. High soil fertility (0.73-0.82) is particularly advantageous for densification and yield increase, resulting in yield increments ranging from 0.99 to 2.16 t ha. Appropriate tillage methods can significantly improve soil fertility, and the effects of straw incorporation with subsoiling (SSR) and straw incorporation with deep tillage (DPR) are the best. Enhancing soil fertility through tillage and straw return measures can markedly augment grain weight by changing maize grain filling characteristics, ultimately achieving the cultivation goal of increased density and yield.