Experimental Study on Straw Rotting and Returning Mode in the Cold Region of Northeast China

The delayed decomposition of rice straw in Northeast China’s cold regions (winter temperatures < −20 °C) due to insufficient accumulated temperature requires innovative solutions. This study developed a synergistic approach combining microbial decomposition with mechanical burial. Pre-experiments identified optimal parameters for the liquid decomposing agent (100 mg/mL concentration, 6 g/m application rate). A novel combined machine was engineered with adjustable parameters: knife roller speed (200–300 r/min), burial depth (15–25 cm), and ground clearance (80–120 mm). Field trials demonstrated a 91.3% straw return rate under optimized settings (220 r/min, 100 mm clearance, 1.7 m/s speed), representing a 28.5% improvement over conventional methods. Spring burial enhanced straw decomposition to 83.6% within 60 days (vs. 67.2% in autumn), significantly increasing soil organic matter and available nitrogen. The integrated technology achieved 1.5 hm2/h operational efficiency, meeting regional agronomic demands. This study provides a replicable model for cold-region straw utilization, aligning with carbon sequestration goals in black soil conservation.