Evaluating the effects of biochar on the hydraulic properties of acidified soil in China

Purpose The increased human activities have significantly promoted the acidification of cultivated soils decreasing the soil water retention properties. This study investigated the improvement effect and mechanism of biochar on water retention properties of acidic soils. Materials and methods Biochar was mixed with acidified and molded soils in different amounts (0, 2, 5, 8, and 10%), and then soil hydrological and water infiltration characteristics were analyzed. Results and discussion The soil application of biochar, improved acidified soil capacity and porosity, and the effects were directly proportional to the applied amount of biochar. Compared to the control group, the application of 10%, biochar improved the average soil water content by 2.1–2.2 times and reduced the soil vertical infiltration rate by 41–43%. The soil vertical infiltration was 23–25% of that in the control group. Moreover, biochar-mediated improvement of soil aggregate agglomerates was found to be associated with the adsorption of soil microaggregates and the formation of water-stable macroaggregates. Conclusion This study found that applying biochar to acidified soils can relieve the problems of poor water retention with a clear improvement mechanism. Large-scale soil application of biochar preventing migration of soil ions can contribute to environmental protection and natural resources recycling.