LAUSR

Abstract Adding biochar to soil is an efficient method to improve soil physicochemical properties. Understanding the effect of this method on soil and water loss is also important. However, there is insufficient data available to assess this effect. Thus, a simulated rainfall (intensity 90 mm h−1) study was conducted to explore the effect of biochar particle sizes (2–1, 1–0.25, and 2 mm water-stable soil aggregate content, and soil saturated hydraulic conductivity (Ksat) from a perforated box (1 m long and 0.4 m wide) with a 27% slope gradient that contained soil, with a constant application rate of biochar at 1% (wt/wt). Soil without biochar was used as the control. The results indicated that biochar-treated soil delayed the time to runoff compared to the control by 12.67% to 32.58%, with the smallest particle size ( 2 mm water-stable soil aggregate content and Ksat relative to the control. We speculated that the positive effects of biochar on soil and water loss were possibly due to an improvement in soil physical properties, such as an increase in the >2 mm water-stable soil aggregate and Ksat.