Abstract: “3414” fertilizer effects test design scheme was adopted to carry out field experiments to explore the optimal amount and ratio of nitrogen, phosphorus and potassium fertilization in waterlogged paddy soil rice. The current recommended amount of nitrogen fertilizer (N 180.0 kg/hm²), amount of phosphorus fertilizer (P₂O₅ 67.5 kg/hm²) and amount of potassium fertilizer (K₂O 90.0 kg/hm²) on rice yield increase was studied. The results showed that fertilization increased the yield significantly, with an average yield increase of 235.1~3 066.6 kg/hm², with growth of 3.5%~45.3%. Fertilization increased the gross income by 587.8~7 666.5 yuan/hm², increased the investment by 886.5~2 361.1 yuan/hm², the yield to investment ratio was 0.7~3.9, and the net income was -298.5~5 697.0 yuan/hm². The agronomic utilization rate of nitrogen fertilizer was 8.7~19.5 kg/kg, 13.5 kg/kg for P₂(P₂O₅ 67.5 kg/hm²) and 4.8 kg for P₃(101.3 kg/hm²), and 6.5 kg/kg for K₂(90.0 kg/hm²).

Key words: rice, fertilizer effect test, benefit, input-output ratio, agronomic utilization rate