Effects of different straw return methods on soil properties and yield potential of maize

Long-term continual straw return can enhance soil quality and increase crop yields by perpetually altering the soil environment. However, little is known about how different straw return methods affect soil physicochemical properties, enzymatic processes, and crop yields. The study aims to determine how different straw return practices improve soil structure, nutrients, enzyme activities, and maize yields. In this experiment, a field trial was conducted in 2021-2022 in the irrigated area of the Tumochuan Plain Irrigation District to determine the effects of four different straw returns on soil structure, nutrients, enzyme activities, soil quality, and maize yields. The four types of straw return included straw incorporation with deep tillage (DPR), straw incorporation with subsoiling (SSR), no-tillage mulching straw return, and farmer's shallow rotation (CK). Our results showed that DPR and SSR enhanced water retention capacity by reducing the bulk weight of the 0-45 cm soil layer. DPR and SSR significantly increased soil organic C (12.76%), total nitrogen (25.32%), and available nutrients (i.e. AP, NO₃^--N) in the 0-45 cm soil layer compared to CK, whereas there were no differences between straw-returned treatments in the 0-15 cm soil layer. Finally, maize yield was significantly increased by 13.14% and 11.41% in the second year of DPR and SSR, respectively, compared to CK. This study demonstrated that DPR and SSR are effective at enhancing the agricultural utilization of crop residues and represent feasible strategies for improving physical, chemical, and biological processes in continuous maize cropping systems, leading to increased crop productivity.