Abstract
Some investigations were made to clarify the effects of charcoal on soil environment and the yield of sweet potato (Ipomoea batatas Lam.). Because charcoal contains a large amount of potassium, application of charcoal increased the contents of exchangeable potassium in the soil. When applied at a rate of 2, 000kg/10a, charcoal improved thc physical properties of the soil. That is to say, it increased the gaseous phase and porosity, decreased the solid and gaseous phase, and helped create environment where sweet potato can easily absorb potassium. As a result, it was clarified that the use of charcoal increased the K2O-N ratio in the tuberous root and promotes the growth of the tuberous root, thus increasing the yield of sweet potato.
