Objectives The objective of this study was to investigate the effects of coated controlled-release nitrogen fertilizer and matrix slow-release nitrogen fertilizer on the agronomic and environmental effects of rice.

Methods A field experiment was conducted on late rice in Jiujiang City, Jiangxi province, comprised four treatments: conventional urea with one-time basal and one-time topdressing (U), single application of coated controlled-release nitrogen fertilizer (P), a single application of matrix slow-release nitrogen fertilizer (M), and no nitrogen control (CK). After each nitrogen fertilizer application, continuously monitored ammonia volatilization and nitrous oxide emission fluxes to calculate total ammonia and nitrous oxide losses. From transplanting onward, collected leachate samples every 10 days and surface runoff samples after each rainfall to determine ammonium and nitrate contents, enabling calculation of nitrogen losses from leaching and runoff. During the five key growth stages, soil samples from the 0−20 cm layer were collected to determine ammonium and nitrate nitrogen content. Concurrently, plant samples were taken to assess biomass and nitrogen uptake. At maturity, rice yield and its contributing factors were investigated.

Results The rice yield under P and M treatments increased by 29.3% and 30.2% compared to U, respectively, with nitrogen use efficiency improving by 20.6 and 17.8 percentage points. Compared to U, a single application of P significantly reduced ammonium nitrogen content in paddy fields during the seedling stage, increased nitrogen accumulation in rice during the tillering-jointing and jointing-heading stages by 12.3% and 39.9%, respectively, and markedly decreased ammonia volatilization by 33.4%, leaching by 12.3%, and runoff losses by 44.5%, leading to a 33.6% reduction in total reactive nitrogen losses. A single application of M increased nitrogen uptake by 109.3% during tillering-jointing stages, enhanced early nitrogen accumulation, reduced leaching losses by 16.5%, increased runoff losses by 74.6%, and elevated total reactive nitrogen losses by 16.8%, compared to U.

Conclusion A single application of coated controlled-release nitrogen fertilizer with a release duration of approximately 90 days significantly reduced ammonium nitrogen levels during the rice seedling stage and enhanced nitrogen uptake during the tillering to heading stage. This nitrogen supply shift from earlier to later stages increased rice yield and nitrogen use efficiency, with a notable reduction in total reactive nitrogen losses, thus offering positive environmental benefits. In contrast, a single application of matrix-based slow-release nitrogen fertilizer increased ammonium nitrogen content in paddy soil during the seedling stage and significantly boosted nitrogen uptake during the tillering to jointing stage, but had no significant effect on nitrogen uptake during the jointing to heading stage. Consequently, matrix slow-release fertilizers exhibit good yield-increasing effects but require improvement in their environmental performance.