A Study on Infiltration Characteristics and One-Dimensional Algebraic Model Simulation in Reclaimed Soil with Biochar

The cultivated land area in China is approaching the red line of farmland protection. The newly reclaimed land will become a vital reserved land resource, and it possesses a large exploratory potential. Newly reclaimed soil usually has low productivity with poor physical and chemical properties as well as weak fertility, and it is prone to serious soil erosion. The effects of corn straw biochar and rice husk biochar (at the mass ratio of 2%, 4%, and 8%) on the soil infiltration process and soil moisture distribution in the soil profile were studied. The results showed that the infiltration duration was prolonged, and the wetting front migration distance and infiltration rate were decreased under biochar addition treatments, except under the low addition rate for rice husk biochar. The Philip model and Kostiakov model accurately described the water infiltration process of the newly reclaimed soil with both kinds of biochar. The two kinds of biochar used in this study affected both the initial infiltration rates and stable infiltration rates, and water infiltration was more sensitive to rice husk biochar and its addition rate. The moisture in the soil profile after infiltration was simulated using a one-dimensional algebraic model. The surface soil moisture was improved with both kinds of biochar addition, and the water retention ability was enhanced with an increased biochar addition rate. In conclusion, corn straw biochar with a high addition rate is beneficial for inhibiting soil water infiltration and improving weak water retention ability in the newly reclaimed area, which is a recommended choice for efficient soil construction in newly reclaimed land.