Abstract:

To investigate the effects of combined application of conventional urea and slow-release urea on rice yield and phosphorus fertilizer use efficiency, a field experiment was conducted with six treatments: CK (no fertilizer), NK, N2K, NPK, N2PK, and N3PK. The results showed that under straw return conditions, the rice grain yield of the no fertilizer treatment (CK) was the lowest, at 5 577 kg·hm^-2, accounting for 60.10% of the yield in the NPK treatment, indicating a fertilizer-induced yield increase contribution rate of 39.90%. The average grain yield of the no-phosphorus treatments (NK and N2K) was 86.46% of that of the phosphorus-applied treatments (NPK, N2PK, and N3PK), demonstrating a phosphorus fertilizer contribution rate of 13.54%. Compared with CK, the phosphorus-applied treatments (NPK, N2PK, and N3PK) significantly (p<0.05) increased rice grain yield, with the combined slow-release urea treatments (N2PK and N3PK) showing particularly notable effects. Compared with the no-phosphorus treatments (NK and N2K), the combined slow-release urea treatments (N2PK and N3PK) significantly enhanced grain yield, straw yield, straw phosphorus content, grain phosphorus uptake, and straw phosphorus uptake. Compared with the NPK treatment, the combined slow-release urea treatments (N2PK and N3PK) increased the apparent phosphorus recovery efficiency by 11.2 percentage points. In conclusion, under the experimental conditions, the combined application of slow-release urea (N2PK and N3PK) is recommended to effectively improve rice yield and phosphorus fertilizer use efficiency.

Key words: rice, slow-release urea, phosphorus fertilizer, fertilizer use efficiency, yield