为了解江苏省洪泽县水稻土壤有效磷临界值和磷肥效应,以淮稻5号为供试水稻品种进行田间试验。结果表明:水稻施用磷肥的增产效果显著,与不施磷相比,增产率达13.2%～40.6%;磷肥施用量与水稻产量之间的关系符合二次多项式曲线方程,磷肥极限用量为113.7 kg/hm~2,经济用量为107.5 kg/hm~2;水稻土壤有效磷含量的临界值为28.6 mg/kg,每提高1 mg/kg土壤有效磷含量需施12.7 kg/hm~2磷肥。 In order to understand the threshold value of P available and the effect of phosphate fertilizer on paddy soil in Hongze County, Jiangsu Province, a field experiment was conducted with Huai 5 as tested rice varieties. The results showed that the yield increasing effect of applying phosphate was significant, and the yield was 13.2% ~ 40.6% compared with no phosphorus application. The relationship between the application of phosphorus fertilizer and rice yield was in accordance with the quadratic polynomial curve equation. The limit of phosphate fertilizer application was 113.7 kg / hm ~ 2, and the economic amount was 107.5 kg / hm ~ 2. The critical value of available phosphorus in paddy soil was 28.6 mg / kg, and 12.7 kg / hm ~ 2 P was needed for every 1 mg / kg of soil available phosphorus.