Effects of the decomposition agent application on the physicochemical properties and microbial community structure of wheat straw-returning soil

Applying decomposition agents for straw return can not only accelerate straw decomposing, but also reduce the use of chemical fertilizers and improve soil fertility. However, the mechanism of applying the decomposition agent on the soil environment is not clear yet. This study investigated the effects of straw returning with a decomposition agent on the soil environment during four stages of wheat growth and development. The application of decomposers increased the Total Nitrogen (TN) content in the soil by 237.7% and 102.2% at heading and maturity stages, respectively. The Available Phosphorus (AP) content in the soil at the jointing stage increased by 10.3%. The Total Potassium (TK) content and the Available Potassium (AK) content in the soil at maturity, increased by 23.8% and 25.3%, respectively. The High-throughput sequencing results showed that soil microbial abundance and community structure changed after applying the decomposition agent. The abundance of active flora showed different trends during different growth periods of wheat. The network analysis showed that applying the decomposition agent complicated the microbial interactions in the soil and the mechanisms of utilization of organic components. Structural equation modeling (SEM) indicated that applying the decomposition agent accelerated the release of nutrients from the straw, influenced the microbial community structure, and further increased the activity of soil enzymes during different growth periods of wheat. The above findings will help to explore the mechanism of the effect of straw returning with a decomposition agent on the soil environment.