Rapid High-Temperature In Situ Decomposition Technology of Corn Straw in Fields: Process, Mechanism and Application Potential

Aiming at tight farming schedules, slow straw decomposition, and severe soil-borne disease risks in the practical maize straw returning production of China’s wheat–maize double cropping zones, this study developed a field-adapted in situ rapid high-temperature straw composting technology matched with a special composite microbial inoculant. Post-harvest summer maize straw collected from the field was crushed to 3–5 cm; the inoculant group T and water control CK were arranged with three biological replicates. Raw materials were adjusted to 65% moisture and loosely stacked into trapezoidal piles equipped with layered temperature–humidity sensors covered by plastic film for continuous monitoring. After formula and pile structure optimization, the pile temperature exceeded 50 °C within 8 h and stayed at 58–63 °C for 9 days, limiting the composting cycle to within 15 days. Cellulose and lignin degradation reached 56.25% and 50.39%, respectively; available P and K rose by 12.33% and 14.69%, free amino acids doubled; the C/N ratio dropped to 18:1 and the GI exceeded 130%. High temperature enriched functional flora of Bacillus subtilis, Aspergillus niger and actinomycetes, whereas pathogenic Fusarium abundance decreased to less than 1/31 of the initial level. This technology can bring approximately 400 yuan of potential additional benefit per mu, providing an efficient and labor-saving practical candidate for straw returning in regions with a high multiple-cropping index.