The relationship between change in soil structure induced by application of cow’s compost and yield of paddy rice was investigated in 1/2000 a pot trials. Three fertilization treatment were set up by compost application at the rate of 100%,50% or 0%,and adjusted to the total concentration of three major nutrients (NPK) with application of chemical fertilizer. Compost application gave considerable increase in rice yield. The increase in rice yield can be explained by the following effects. One was slower mineralization of compost than chemical fertilizer, hence, the nutrient-absorption pattern of rice in this situation increased yield. The other effect was the decrease in the solid phase of the soil induced by compost application. This study showed the difficulty of dividing the effects of compost application into chemical and physical effects.
