Abstract: To elucidate the relationship between crops and soil erosion, we examined the effects of two crops, sorghum Keza 18 (SO) and maize Keyu 19 (MA), on soil water infiltration characteristics, through the analysis of crop roots, soil physical properties and infiltration rate in Keshan County, Heilongjiang Province, a water erosion zone in Northeast China. The results showed that soil bulk density of 0-20 cm layer in SO treatment was significantly increased by 6.15% compared to the MA treatment. The total porosity and non-capillary porosity were significantly decreased by 5.93% and 15.63%, respectively. The saturated water capacity and field water capacity decreased significantly by 6.38% and 6.11%, respectively. Soils under both SO treatment and MA treatment were dominated by 0.25-2 mm particle size aggregates. The mean weight diameter and geometric mean diameter of soil in SO treatment were significantly reduced by 29.57% and 4.60%, respectively, compared to MA treatment. In the soil layers of 0-20, 20-40, 40-60 and 60-80 cm, root weight density of MA treatment was 1.67, 2.46, 4.52, and 2.27 times of that of SO treatment, respectively. The initial infiltration rate, stable infiltration rate, saturated hydraulic conductivity and average infiltration rate of SO treatment were significantly reduced by 19.11%, 15.50%, 15.63%, and 14.86%, respectively, compared with MA treatment. The Kostiakov model, Horton model and Philip model were used to simulate the soil infiltration processes. The Horton model had the largest R² and the best fitting effect on the soil infiltration processes. The infiltration rate was significantly negatively correlated with bulk density, and positively correlated with other indices. Furthermore, root system of dwarf sorghum grown in this region was shallower than that of maize, with a larger capacity and slower infiltration rate, which easily leads to surface runoff and increases the risk of water erosion. Our results can provide data reference for the prevention and control of soil erosion in this region.

Key words: Northeast China’s black soil area, sorghum, maize, soil infiltration, crop root