Effects of optimized nitrogen fertilizer management on the yield, nitrogen uptake, and ammonia volatilization of direct-seeded rice

Direct-seeded rice has been developed rapidly because of labor savings. Changes in rice cultivation methods put forward new requirements for nitrogen (N) fertilizer management practices. Field experiments with five different fertilizer ratios of basal, tillering and panicle fertilizer, namely N1 (10:0:0), N2 (6:2:2), N3 (4:3:3), N4 (2:4:4) and N5 (0:5:5), were conducted to investigate the effects of different N fertilizer management practices on yield formation, N uptakes, and ammonia (NH₃ ) volatilization from paddy fields in direct-seeded rice.

The results showed that the N4 treatment improved grain yield by 5.1% while decreasing NH₃ volatilization by 20.4% compared with that of conventional fertilizer treatment (N2). The panicle number per unit area was the key factor to determine the yield of direct-seeded rice (72%). Excessive N application of basal fertilizer (N1) reduced seedling emergence, N use efficiency, and yield by 45.3%, 160.6%, and 6.9% respectively and increased NH₃ volatilization by 28.1% compared with that of the N4 treatment. Removal of basal N fertilizer (N5) N reduced spike number and yield by 13.0% and 6.9% respectively, minimizing NH₃ volatilization while affecting the construction of high-yielding populations compared with that of the N4 treatment.

Optimized N fertilizer management achieved delayed senescence (maintenance of higher leaf Soil Plant Analysis Development meter values in late reproduction), higher canopy photoassimilation (suitable leaf area), higher N fertilizer use efficiency, and less N loss (lower cumulative NH₃ volatilization). © 2023 Society of Chemical Industry.