Abstract:

Three types of soil textures (loam, sandy loam, and clay) from corn fields in western Liaoning province in 2021 were selected, along with different precipitation levels (light rain, moderate rain, and heavy rain) for continuous 7 days and every other day for 7 days after that.The relative soil moisture data for 0~50 cm depth was collected.The characteristics of soil moisture recession for different precipitation levels, soil textures, and soil depth recession coefficients (K) during the corn growing season in this region were analyzed, and a soil moisture prediction model was constructed.The results show that the soil moisture recession process in corn fields of western Liaoning can be divided into three stages: rapid recession, slow recession, and stagnant recession.The average recession rate during the rapid recession stage for the three soil textures was 7.21 mm·d^-1, with clay soil having a 9%-12% higher rapid recession rate than other soil textures.There were no significant differences in the slow recession and stagnant recession rates among different soil textures.The K value of the shallow layer (10~20 cm) was significantly smaller than other soil layers and had the largest dispersion.The fluctuation range of K values in the 50 cm soil layer increased significantly under heavy rainfall conditions.There was a significant negative correlation between K values and precipitation (R=-0.92).Under the same rainfall level, the K value of clay soil was 12%-20% lower than that of loam and sandy loam.The monthly variation of K values showed the highest in March, lowest in late August, and rebounded to a relatively high value in late November.Based on the soil moisture balance equation, a soil moisture recession model was constructed.The simulation accuracy was best for light rain levels, and the simulation results for shallow soil layers were better than those for deep layers.

Key words: Precipitation levels, Soil texture, Recession rate, Soil moisture balance equation