LAUSR

BACKGROUND 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. RESULTS The results showed that the N4 treatment improved grain yield by 5.1% while decreasing NH3 volatilization by 20.4% compared to 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, NUE and yield by 45.3%, 160.6% and 6.9%, respectively, and increased NH3 volatilization by 28.1% compared to 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. CONCLUSION Optimized N fertilizer management achieved delayed senescence (maintenance of higher leaf SPAD values in late reproduction), higher canopy photoassimilation (suitable leaf area), higher N fertilizer use efficiency and fewer N losses (lower cumulative NH3 volatilization). This article is protected by copyright. All rights reserved.