Effect of straw return practices on soil physico-chemical properties and maize yield

Highly intensive agricultural production has led to a decline in the quality of cultivated land and soil degradation. Straw return is an important method for improving the soil environment and increasing soil organic matter content. However, the current method of straw return mainly focuses on the surface soil, ignoring its effects on improving the quality of the subsoil. Five straw return practices were investigated: deep-injected straw incorporation (DI-SI), straw mulching (SM), straw incorporation (SI), deep-ploughed straw incorporation (DP-SI), and straw removal (SR). The objective of this study was to investigate the impacts of various straw return methods on the physical and chemical properties of different soil layers and maize yield. The aim is to offer scientific evidence for the efficient utilization of straw resources and contribute to enhancing soil quality and crop yield. The results showed that straw mulching increased soil water content, soil organic carbon, and N-acquisition enzyme activities in the 0−20 cm soil layer; deep-plughed straw incorporation increased soil water content and P-acquisition enzyme activities in the surface soil. Deep-injected straw incorporation significantly decreased soil bulk density and increased soil water content, soil organic carbon, total nitrogen content, mineral nitrogen content, and extracellular enzyme activities in the 20−40 cm soil layer. Compared with straw removal, straw return methods significantly increased maize yield by 13.4%−21.0%. Therefore, straw return is an important way to efficiently utilize straw resources, which is conducive to improving the soil environment of farmlands, increasing soil nutrient content, reducing the use of chemical fertilizers, promoting crop yield, and significantly contributing to the sustainable development of agriculture. Deep-injected straw incorporation plays an important role in improving subsoil quality, expanding the soil carbon pool, and improving cultivated land quality and productivity, and can be considered an effective measure to build a deep and fertile plow layer.