Evaluation of Agronomic and Economic Performance of Controlled and Slow‐Release Nitrogen Fertilizers in Two Rice Cropping Systems

Abstract

Core Ideas The mixed treatment increased rice grain yield, recovery efficiency of N, and net profit to different extents in two rice cropping systems. No significant differences in agronomic performance between urea formaldehyde and common urea. Urea formaldehyde provides little economic benefit to rice production. This study investigated the agronomic and economic efficiency of urea formaldehyde (UF) and a mixture of controlled‐release and common urea (CU) in rice (Oryza sativa L.) production. Two 3‐yr field experiments were conducted in Jinhua, China, via four treatments: no N fertilization, split applications of CU, a single UF application, and a mixed treatment comprising a polymer coating of sulfur‐coated urea (PSCU) and CU. The mixed treatment led to significantly higher grain yields by 4.7 to 12.2 and 5.7 to 8.9% for late and single rice, respectively, than those in the CU treatment. The UF treatment had small to nonsignificant improvements (0.2–2.3% for late rice; 1.7–4.3% for single rice) in grain yield relative to the CU treatment. The recovery efficiency of N (REN) in the mixed treatment was enhanced by 4.8 to 32.9% in early rice, 29.2 to 67.6% in late rice, and 13.1 to 21.2% in single rice. The mixed treatment resulted in significantly higher soil NH4+–N concentrations during the tillering to heading stage for both cropping systems. The net profit was US$111 to 257 ha−1 higher than under the CU treatment. However, a single application of UF did not substantially increase net profit (US$17–47 ha−1) in early rice and single rice and decreased the profit (US$17 ha−1) in late rice, relative to the CU treatment. Overall, the mixture of PSCU and CU could be a promising alternative as a controlled‐release N fertilizer for sustainable increases in rice grain yield, REN, and net profit.