Effects of Biochar on Infiltration and Evaporation of Soil Water with Sand Mulching

Water shortages and soil salinization in arid regions of northwestern China have become an important factor limiting agricultural production and affecting the living conditions of farmers. Using existing water resources and salinized land scientifically and efficiently is important for improving agricultural production. We studied the characteristics of the infiltration and evaporation of soil water under the application of different amounts of biochar in indoor soil-column simulations with sand mulching to determine the effect of biochar on the infiltration and evaporation of soil water. We tested five treatments: sand mulching with no biochar (CK) and sand mulching with 0.5, 1.5, 2.5 and 4.5% biochar. Cumulative infiltration and the rate of migration of the wetting front were higher with 0.5 and 1.5% biochar and lower with 2.5 and 4.5% biochar than CK, respectively. The distance and duration of migration of the wetting front followed the power function F = a center dot t(b), a relationship consistent with the Kostiakov model of infiltration. The cumulative evaporation of soil water was higher with 0.5 and 1.5% biochar and lower with 2.5 and 4.5% biochar than CK. The variation of cumulative evaporation was represented well by both the Black and Rose models of evaporation. The results of this study have important implications for the application of biochar in arid regions of northwestern China for improving the hydrological characteristics of soil in agricultural practices.