LAUSR

Abstract As biochar affects soil hydrological processes, a detailed laboratory experiment was run to investigate the effect of three biochar application rates of 1, 2, and 3 kg m−2 under three successive simulated rainfall events (three rounds) with about 10-day intervals on runoff rate, soil loss, salinity of runoff and percolated water of a loamy soil. Rice husk biochar produced in 600 °C for four hours was mixed in the top 0–1.5 cm of the soil surface. A simulated rainfall intensity of 28 mm h−1 was applied for 60 min over the soil bins measuring 1.4 m × 1.4 m × 0.1 m. Results showed that the 3 kg m−2 application of biochar prevented runoff generation, and consequently there was no soil loss. The 2 kg m−2 application of biochar significantly reduced runoff rate, runoff coefficient, and soil loss compared to the 1 kg m−2 and the control (no biochar application). In addition, the 2 kg m−2 application of biochar significantly increased the time to runoff generation, which clearly implies an appropriate amount of biochar could control runoff rate and soil loss. The rainfall rounds had significant effects on the time to runoff generation, total soil loss, and the peak of runoff salinity. A combined analysis showed that a power function can be satisfactorily fit to the runoff and soil loss rates. In terms of environmental concerns of biochar application, results revealed that rice husk biochar might not be an environmental threat and the salinity of runoff and percolated water were lower than 1 dS m−1. In conclusion, this study showed that rice husk biochar at certain amounts could be used to reduce or prevent runoff and soil loss in loamy soil in a semi-region area.