The Role of Aggregate Stability and Dispersed Clay in Rainfall Splash Erosion

ABSTRACT While soil aggregates significantly influence splash erosion, the characteristics of clay particles released during aggregate breakdown and their impact on raindrop splash remain poorly understood. This study investigated the role of soil binding agents in controlling aggregate stability, clay classes released from aggregate, and splash erosion across three soil types (red, calcareous, purple). Red soils showed significantly smaller aggregate stability (MWD = 0.58 mm) and greater release of clay fractions from aggregate breakdown, including both water‐dispersible clay (WDC) (12.46%) and water‐reflocculable clay (WRC = 30.6%), compared to calcareous (MWD = 0.85 mm, WDC = 33.1%, WRC = 2.8%) and purple soils (MWD = 0.84 mm, WDC = 32.2%, WRC = 0.94%). This was attributed to their distinct binding agent composition: red soils were dominated by free Fe oxides (Fe d = 104 g kg −1 ), while calcareous and purple soils exhibited greater soil organic matter (SOM = 9.4–10.3 g kg −1 ) and CaCO 3 contents (0.80%–2.5%). Stepwise regression and correlation analyses revealed SOM consistently enhanced MWD and non‐dispersible clay (NDC) across all soils, whereas CaCO 3 and chelated Fe oxides (Fe p ) showed soil‐specific stabilization effects on MWD, WDC, WRC, and NDC. Total splash erosion was 29.4%–53.5% greater in red soils versus calcareous soils and purple soils, with splash loss negatively correlated to MWD and NDC but positively to WDC ( p < 0.05). These findings demonstrated that splash erosion was jointly controlled by both aggregate MWD and WDC, with soil‐specific binding mechanisms governing these aggregate properties. These findings improve mechanistic understanding of aggregate effect on splash erosion and may improve future erosion modeling.