Promotion of biochar on adsorption of cadmium and retardation on water transport in paddy soil

The effects of biochar on the pH of soil, adsorption of cadmium, and water transport in paddy soil were studied in this paper. The soil pH was measured at a 1:1 soil/water ratio. The pH of the soil increased with an increasing amount of the applied biochar. The pH of topsoil and subsoil increased by 1.5 and 0.84, respectively, for the 9% fine biochar treatments. But the increment of soil pH decreased with an increasing amount of applied biochar, and fine biochar was more effective to increase the soil pH. The Cd adsorption isotherms of soil with different biochar treatments were tested at a 1:10 soil/solution ratio. The results showed that the ability of water transport decreased with the increasing amount of biochar addition. All of the factors including the quality of biochar, soils, and cropping systems should be taken into consideration when applying specific types of biochar in specific regions and for specific cropping systems.