Effects of Tillage Practices and Plastic Film Mulching on Soil Temperature, Dry Matter Production, and Yield Formation of Maize in a Cool Region

Limited thermal resources in the cool regions of Northeast China restrict maize growth and yield formation. A two-year field experiment was conducted in Dunhua, Jilin Province, China, during 2024–2025 using four tillage practices—deep rotary tillage (SX), deep harrowing (SB), deep plowing (SF), and subsurface rotary tillage (QX)—combined with plastic film mulching or no mulching. Soil temperature, leaf area index (LAI), photosynthetic characteristics, dry matter accumulation, and grain yield were evaluated. Mulching increased soil temperature by 1.27–6.37 °C in 2024 and 1.37–5.20 °C in 2025, promoted canopy development, and improved photosynthetic performance. It also increased dry matter accumulation at V8 by 61.42–87.31% and enhanced post-silking dry matter accumulation. Grain yield increased by 7.93–10.51% in 2024 and 4.94–10.27% in 2025. Deep rotary tillage with mulching (SXC1) produced the highest yield in both years. Correlation analysis showed that soil temperature, LAI, and post-silking dry matter accumulation were closely associated with yield. Overall, deep rotary tillage combined with plastic film mulching improved the soil thermal environment, dry matter production, and maize yield in cool regions.