The surface soil anti-scouribility and aggregate loss characteristics in cultivated land of the black soil area

Soil erosion can cause the dispersion and breakdown of soil aggregates. One key indicator of soil erosion resistance is soil anti-scourability. In black soil regions, the surface soil of cultivated land is particularly vulnerable to the scouring effects of runoff. This runoff can further break down and disperse soil aggregates. Therefore, studying the soil's anti-scourability, as well as the erosion characteristics of soil aggregates of different particle sizes in the surface soil of black soil cultivated land, is essential. To investigate the anti-scourability and aggregate loss characteristics of surface soil in cultivated land of the black soil area, the undisturbed soil (0-6 cm) was taken as the research object. The relationships between soil anti-scourability coefficient, scouring duration, scouring amount, and soil aggregate loss characteristics were explored, with 5 scouring amounts (6, 12, 18, 24, and 30 L/min) under indoor simulated runoff scouring experiments. The aim was to reveal the anti-scourability of the surface soil and the impact of runoff scouring on aggregate loss characteristics in cultivated land of the black soil area. 1) Overall, the total amount of soil loss gradually increased with the increase of scouring amount. The total amount of soil loss at a scouring amount of 18 L/min was 1.50 times that of 6 L/min. The soil loss decreased exponentially with decreasing scouring duration. 2) Under the conditions of scouring amounts of 6, 12, and 18 L/min, the soil anti-scourability coefficient increased as a power function with scouring duration. The soil anti-scourability coefficient was highest at a scouring amount of 18 L/min within 15 minutes, which was 2.01 and 1.38 times that at 12 and 6 L/min, respectively. 3) The loss characteristics of soil aggregates were differently affected by the scouring amount. Overall, the stability of soil aggregates gradually decreased with the increase of scouring amount, and the mass percentage of < 0.25 mm aggregates gradually increased. Conversely, the mass percentage of > 2 mm aggregates gradually decreased. The fraction size of 0.5-1 mm aggregate was the main lost fraction size under different scouring amounts, accounting for 26.84%-29.66%. 4) Compared to before runoff scouring, the mass percentage of <0.25 mm aggregates under the scouring amounts of 6, 12, and 18 L/min increased by 2.49, 14.17, and 4.18 times, respectively. 5) The erosion resistance of soils gradually decreased as the scouring amount increased. The fractal dimension of soil aggregates at a scouring amount of 18 L/min was 1.05 times that of 6 L/min. The total amount of soil loss in the surface soil of cultivated land of the black soil gradually increased with the increase of scouring amount. At the same time, the soil anti-scourability became stronger and the stability of soil aggregates gradually decreased. Additionally, the erosion resistance of soil under the 3 scouring amounts was ranked as 6 > 12 > 18 L/min. The research results provide insights into the changes in the surface soil anti-scourability in cultivated land of black soil and offer references for agricultural land use.