Optimizing nitrogen fertilizer application protocol to minimize the risk of nitrogen loss while maintaining high...

Direct-seeded rice is popular for saving labor, simplifying cultivation, and reducing costs, but it involves new challenges of shallow root systems and short growth periods that require optimizing the time, frequency and proportion of nitrogen (N) fertilizer application. Field experiments with five different fertilizer ratios of basal, tillering and panicle fertilizer, namely N_180-0-0, N_90-90-0, N_54-126-0, N_54-72-54 and N_0-90-90, were conducted to investigate the effects of different N fertilizer management protocols on yield formation, N uptakes, utilization and N loss from paddy fields in direct-seeded rice.

Optimizing the N fertilizer application protocol (N_54-72-54) for direct-seeded rice produced significantly higher yield by 13.3%, N accumulation by 33.4%, and N recovery efficiency by 50.7% compared to excessive basal N (N_180-0-0). Excessive basal N (N_180-0-0) reduced seedling emergence and tiller formation by 28.6% and 42.5%, respectively. Excessive spike N (N_0-90-90) decreased root length, root volume, and N metabolism enzymes at the tillering stages, increased SPAD (soil plant analysis development) values and leaf area at the filling stages but reduced filled grain rate by 7.7%. Optimizing the N application protocol (N_54-72-54) reduced ammonia (NH₃) volatilization by 18.6% and runoff N losses by 13.1%.

Optimizing the N fertilization application protocol significantly increased rice seedling emergence rate and tiller number, improved root morphology and enhanced N metabolism enzyme activities, Increased SPAD value and leaf area index, and reduces N losses (NH₃ volatilization and runoff losses). The optimal N fertilizer application protocol for direct seeded rice was N_54-72-54. © 2025 Society of Chemical Industry.