Spatial variability of soil hydraulic and physical properties in erosive sloping agricultural fields

Abstract

It is essential to minimize soil quality degradation in sloping agricultural fields through stabilization and improvement of soil hydraulic properties using sustainable soil management. This study aimed to analyze the impact of different tillage practices, including conventional tillage (CT), minimum tillage (MT), and zero tillage (ZT), on soil hydraulic conductivity in a sloping agricultural field under maize–wheat rotation. The results showed that the highest runoff volume (257.40 m³), runoff coefficient (42.84%), and soil loss (11.3 t) were observed when the CT treatment was applied. In contrast, the lowest runoff volume (67.95 m³), runoff coefficient (11.35%), and soil loss (1.05 t) were observed when the ZT treatment was adopted. The soil organic carbon and aggregate mean weight diameter were found to be significantly greater (with mean values of 0.79% and 1.19 mm, respectively) with the ZT treatment than with the CT treatment. With the tilled treatments (CT and MT), substantial changes in the saturated soil hydraulic conductivity (k_s), near-saturated soil hydraulic conductivity (k), and water-conducting porosity (ε) were observed between two crop seasons. These three soil parameters were significantly higher in the period after maize harvesting than in the wheat growing period. In contrast, no significant difference in these soil parameters was found when the untilled treatment (ZT) was carried out. With regard to the slope positions, k_s, k, and ε showed different behaviors under different treatments. The toe slope position showed significantly lower k_s and ε values than the summit and middle slope positions. Of the evaluated tillage practices, ZT was found to be the most promising means to improve the soil hydro-physical properties and effectively reduce surface runoff and soil erosion.