Aggregate stability in rainfall‐induced soil physical crusts on the Loess Plateau, Northwest China

Abstract

AbstractComprehensive insights into the aggregate stability of physical crusts enhance the understanding of erosional processes and transport mechanisms. This study evaluated the erosion resistance and aggregate stability in structural and sedimentary crusts of a Lou soil induced by simulated rainfall. A runoff plot (200 cm long × 100 cm wide × 50 cm high) with a slope of 5° was set up to simulate contour tillage (20 cm in ridges, 30 cm in furrows). A single rainfall intensity (60 mm h−1) was applied over six durations (5, 10, 15, 20, 25, and 30 min) to obtain structural and sedimentary crusts. With an increase in rainfall duration, bulk density of structural and sedimentary crusts increased from 1.26 g cm−3 (soil before rainfall) to 1.56 and 1.58 g cm−3, respectively. Macroaggregate contents in structural crust changed slightly (from 7.5 to 7.4%); however, a marked increase (from 9.0 to 18.6%) was observed in sedimentary crust with increased rainfall duration. The mean weight diameter and geometric mean diameter (i.e., the inverse of erodibility factor) in structural crusts were lower than sedimentary crusts developed from all rainfall conditions. The aggregate stability index of structural and sedimentary crusts initially increased from 2.12 and 2.07 with the increase in rainfall duration, respectively, and then leveled off at 2.42 and 2.48. Soil aggregate stability of sedimentary crust, which conferred greater resistance against external erosive forces, was stronger than that of structural crust.