The Annual Variation Of The Responses Of Rice To Applications Of Nitrogen, Phosphorus And Potassium Fertilizers In Paddy Field

By rice nitrogen (N), phosphorus (P), potassium (K) fertilizer "3414" long-term experiment for 4 years from 2008 to 2011, establishing rice fertilizer and production regression equation, the maximum,and optimum amount of fertilization, N use efficiencyand its variation among years were investigated. The results were as follows:1. Based on multiple quadratic equation of nitrogen, phosphorus and potassium, the optimum amount of N fertilizer among years showed an increasing trend, the optimum amount of P fertilizer among years increased after the first drop, and the optimum amount of K fertilizer among years decreased after first increasing. The fourth year's optimum amount of fertilization was closer to the average and became stable.2. Based on single quadratic equation of nitrogen, phosphorus and potassium under suitable fertilization rate, the optimum amount of N fertilizer among years had significantly increasing trend, the one for P fertilizer increased and K fertilizer with a slightly increase. The third year's optimum amount of fertilization closer to the average and became stable. Compared to multiple quadratic equation, the optimum amount of N fertlizer derived from single quadratic equation was less, but achieved greater production. Therefore, it is more appropriate for rice production.3. Rice N use efficiency increased.with increasing of N rate. P, K use efficiency improved by appropriate P and K fertilizer rate, but beyond a certain limit, it reduced. With the increasing of the year, P use efficiency rised, and N, K use efficiency dropped. The fertilizer combination of N3 (258.75 kg·hm-2), P2 (36 kg·hm-2) and K2 (90 kg·hm-2) can serve to achieve better economic and ecological benefits.