Effects of fertilization with reducing nitrogen, controlling phosphorus and stabilizing potassium on rice yield and nutrient accumulation

Excessive application of nitrogen and phosphorus and lower potassium supply not only limit rice growth, but also reduce nutrient use efficiency. In this paper, a field experiment was conducted to study the effects of reducing nitrogen and phosphorus dosages and stabilizing potassium supply on rice yield, nutrient accumulation and fertilizer use efficiency. There were fourteen treatments with two replications. The results indicate that the straw biomass and grain yields of the treatments with integrated N-K, P-K, or N-P-K applications are significantly (P0.05) higher than those of the no fertilizer treatment. The straw biomass of the treatment with less nitrogen and phosphorus and more potassium application (T11, modified treatment, N 225 kg/ha，P2O5 60 kg/ha and K2O 90 kg/ha) is significantly (P0.05) higher than that of the conventional fertilization treatment (CFA, N 300 kg/ha， P2O5 150 kg/ha，K2O 60 kg/ha ) and the differences of kernel weight and grain yield between the two treatments are obvious. The nitrogen and potassium contents in shoots at the tillering stage and in straw at the harvest stage, the accumulated nitrogen and potassium amounts in above ground organs at the harvest stage, as well as apparent nitrogen and phosphorus use efficiencies of the modified treatment are significantly (P0.05) higher than those of CFA. These results imply that properly reducing nitrogen and phosphorus dosages, and increasing potassium dosages could catch nitrogen and potassium need of rice plants, increase dry matter accumulation and grain yield, and improve apparent nitrogen and phosphorus use efficiencies. The fertilization scheme of N 196.2 kg/ha, P2O5 46.5 kg/ha and K2O 90 kg/ha should be recommended for practical rice production under local conditions.