Effects of regulates phosphorus and potassium on rice yield and nutrient absorption

【Objectives】Cold waterlogged paddy field is typical low-production soil, fertilization pattern should be different from general paddy field. A suitable fertilization pattern in the cold waterlogged paddy was studied through adjusting the fertilization pattern on the basis of general paddy field. 【Methods】 A three-years field experiment was conducted in cold waterlogged field in the southeastern Hubei Province. According to the rice yield, yield components and the change of soil nutrients, different fertilization patterns were assessed and the optimum rates of fertilization were proposed.【Results】 The soil available phosphorus contents in the tested paddy fields ranged from 2.7 to 7.3 mg/kg, quickly available potassium from 20 to 80 mg/kg, both were obviously lower than those of the general paddy fields (the average available phosphorus and potassium were 11.5 and 95.8 mg/kg, respectively), and were major nutrient limiting factors in rice production. Fertilization can increase the rice yield obviously, the grain yields of NPK, NP2K, NPK1, NPK+Zn and NPK2 treatments are about 20%-30% higher than those of the CK and farmars' practice treatment (FP). On the basis of NPK, adding silicon, zinc and potassium dosages could increase the grain yield significantly (P0.05), reducing phosphorus and potassium rates has little impact on the yield. The soil available nitrogen and available potassium contents are stable after planting rice for three years, the soil available phosphorus is increased. The contents of potassium in grains and straws in all of fertilization treatments are significantly higher than that of CK, and nitrogen accumulation in grains of all fertilization treatments in significantly higher than that in CK and FP treatments.【Conclusions】 Phosphorus and potassium are the major nutrient limiting factors in rice production in the southeastern Hubei Province, so the phophorus and potassium application rates should be increased. The suitable fertilizer rate in the southeast of Hubei province is N 180,P2O5 90-108,K2O 120 kg/ha. Zinc and silicon fertilizer should be considered at the same time.