Characterization of soil properties and crop physiological changes in reclaimed mining areas with different reclamation years

This study was conducted in the coal mining subsidence reclamation area of Mengcun, City, Henan Province, China, using corn as the test crop. Four treatments were established: 1, 4, and 7 years of reclamation, and normal cultivated land (denoted as 1a, 4a, 7a, and ck). Soil properties and crop physiological growth were monitored at 0-20 cm、20-40 cm and 40-60 cm soil depths to analyze how soil characteristics and crop growth changed with increasing reclamation years, providing insights for accelerating the ecological restoration of reclaimed soils. The results showed that: 1) Soil quality improved with increasing reclamation years. The surface soil organic matter (SOM) and total nitrogen (TN) contents of maize were significantly higher in 4a and 7a than in 1a. Soil pH decreased significantly with reclamation years. Both SOM and TN contents decreased with soil depth. 2) Physiological indicators, including chlorophyll content (SPAD) and photosynthetic characteristics of maize, increased with reclamation years. The net photosynthetic rate (Pn) of maize during the growing season was 18.89 % to 38.97 % higher in 4a and 29.90 % to 65.89 % higher in 7a compared to 1a. 3) During the jointing, tasseling, filling, and maturity stages, soil CO₂ emission fluxes in 4a and 7a increased compared to 1a, by 12.50 % to 27.08 % and 22.86 % to 56.25 %, respectively. The difference between 7a and 1a was significant. 4) Yield indicators, including 100-kernel weight and dry matter weight, improved continuously with increasing reclamation years. Maize biomass in 7a increased by 61.25 % compared to 1a and was not significantly different from the neighboring normal cultivated land (ck).