Changes in water infiltration after simulated wetting and drying periods in two biochar amendments

Biochar impacts soil-water related processes such as infiltration and contributes to the hydrological response of catchments. The aim of this work is to determine the impact of wetting and drying conditions on the infiltration behavior of two biochar amendments and to validate the performance of three infiltration models: Kostiakov, Horton, and Philips. Two materials, sand and a sandy loam, were mixed with 0%, 2.5%, and 5% (by dry wt.) mango wood biochar produced at a highest heating rate of 600^◦C and with a particle size of <63 µm. A sequence of four wetting and drying cycles were simulated. In each cycle, infiltration was measured. We found that biochar addition decreased infiltration because the formation of narrower pores reduced infiltration capacity. The higher the biochar dosage, the more resilient the treatment became concerning the changes on the water infiltrated. Repetitive wetting and drying cycles resulted in a reconfiguration of structural pores affecting the transport of water and air. The infiltration models of Kostiakov and Horton could predict the infiltration dynamics in the amended materials, although they show some instabilities along the WD cycles.