STUDY ON THE EFFECT OF LONG-TERM FERTILIZATION IN DOUBLE RICE CROPPING SYSTEM OF SOUTHERN ANHUI

A ten years fertilizer experiment was conducted in double rice field in Xiutun Basin of Anhui Province. The results showed that the rice plants absorption of nutrients from soil was more than that from fertilizers. Response of rice to fertilizers was in order KN P, and the effect of long-term application chemical fertilizer was gradually reduced with extending years of fertilization. Long-term application of organic manure can keep steadily increasing yield of rice, however,organic manure combined with fetrtilizer(MNPK) the total yield of double rice was lower than that application of inorganic fertilizer(NPK) under the same rate of nutrients condition, indicating organic manure should be applied earlier and raised the ratio of N as basal to meet the needs on nitrogen nutrient of rice seedling growth. Long-term application of chemical fertilizers or organic manures the nutrient contents in soil was increased, except available potassium. Therefore, the emphasise should be given to supply potash in paddy soil and reduce the P rate so as to increase rice yield and income, and maintain the balance of nutrients.