Abstract:In order to study the effect of biochar on the hydraulic characteristics of northeast meadow black soil, establish the model suitable for the soil with addition of biochar, and the ratio (0, 2%, 4%, 6% and 8%) biochar was applied to soil, and the soil hydraulic parameters were tested and numerically analyzed. The results showed that the increase of soil water holding capacity was due to the high ability of water holding capacity of biochar greater than 2200cm suction range, and the improvement of hydraulic conductivity was due to the hydraulic conductivity of biochar at low suction range that lower than 35.82cm. Compared saturated hydraulic conductivity test data with theoretical estimate value, it was showed that the actual measurement values were closed to layered distribution, the max difference was about 8.9%, added biochar soil should be considered as layered distribution. The difference between experimental data and theoretical values was due to the increase of gap in soil by biochar. The water distribution of the soil after infiltrated 24h was simulated by capillary model. The saturation of simulation was 11% lower than actual measured value, which showed that the unsaturated hydraulic conductivity of soil with addition of biochar was fit in capillary model. According to the results of capillary model, the hydraulic conductivity of soil that added biochar was mainly due to the characteristics of biochar, it mainly changed the hydraulic conductivity of soil under low suction. The results showed that application of biochar can improve the hydraulic conductivity of northeast meadow black soil of China, the higher content of biochar added was, the higher hydraulic conductivity was increased. The results also showed that the number of different aperture of capillary was not evenly distributed in biochar, the smaller the aperture was, the more number of capillary was. The capillary model was simple and effective, when the volume ratio of biochar in soil was less than 8%, the numerical analysis results were in good agreement with those obtained with the test data of soil, and it was showed that the model can provide accurate method for numerical calculation. The results can provide a method and guarantee for the study of soil hydrodynamic characteristics under certain biochar application, different areas, different terrains and different permeation times.
