Effects of Continuous Application of Rice Straw Compost on Nutrient Supply Ability in Vegetable Upland Field

Abstract

In alluvial soil, an experiment was carried out for twelve plots in four mineral lot of applying nitrogen, phosphoric acid, potassium and lime, non-fertilizer plot, non-nitrogen plot, non-phosphoric acid plot, non-potassium plot and non-lime plot with compost application of 20 Mg ha^<-1> or non-compost application over twenty-five years. Nutrient supply ability on soil and recovery rate of fertilizer were calculated from the absorption amount of vegetable. 1) In non-nitrogen plot, non-phosphoric acid plot and non-potassium plot on non-compost application, nutrient absorption amount of vegetables of deficient mineral were on the order of potassium, nitrogen and phosphoric acid. 2) With compost application the nutrient absorption amount in each mineral deficiency plot increased as compared with non-compost application through all cultures ; also, the nutrient effects on compost application were on the order of potassium, nitrogen and phosphoric acid. 3) Fertilizer recovery rate of each vegetable with compost application was low as compared with non-compost application. As a reason for the low fertilizer recovery rate, nutrient absorption in each vegetable with compost application depended on soil nutrients more than fertilizer nutrient as compared with on-compost application. In this experiment, nitrogen fertilizer could be decreased 20%, while potassium fertilizer could be decreased 50% in the condition of compost application.