Abstract
Decomposition of the root of Italian ryegrass under both conditions of the paddy field and the upland field was studied. Naturally the production of CO_2 as a characteristic of organic matter decomposition is more active under the upland condition than the paddy field, and by the application of CaCO_3 than that of three elements (NPK) of fertilizer. Consistency of the soil profiles where Italian ryegrass was cultivated is not so strong as those of other plots where the rice straw and the green ryegrass were added or of the manureless plot. Content of humus and exchangeable bases is higher in the plot of Italian ryegrass than in other plots. The nature and properties of soils where Italian ryegrass was grown became very favorable physically and chemically.
