控释尿素减施对双季稻田氨挥发损失和氮肥利用率的影响

【目的】研究连续控释尿素减施对双季稻籽粒产量、N肥利用率和NH₃挥发损失的影响,以期为水稻稳产条件下减少双季稻田氮素损失提供理论依据和技术方法。【方法】以中早39（早稻）和泰优390（晚稻）为材料,设置不同控释尿素N用量的等N量控释尿素(CRU₁)、控释尿素减N 10%(CRU₂)、控释尿素减N 20%(CRU₃)、控释尿素减N 30%(CRU₄)以及尿素(U)和不施肥对照(CK)的6个处理,采用密闭室间歇通气法监测双季稻田NH₃挥发特征,同时测定水稻产量和N含量。【结果】普通尿素(U)处理和控释尿素(CRU)处理施基肥和分蘖肥后早稻NH₃挥发发生在施肥后的8~9 d内,峰值分别于第1~2天和第2~4天出现;晚稻NH₃挥发发生在施肥后的6~7 d内,峰值分别于第2~3 天和第3~4 天出现。早、晚稻生长季U处理总计NH₃挥发损失量(率)最高,分别为47.2 kg/hm² (26.4%)和61.9 kg/hm²(28.7%),产量分别为5.5 t/hm²和6.2 t/hm²,N肥利用率分别为23.0%和20.0%;早、晚稻生长季CRU处理总计NH₃挥发损失量(率)分别为22.8~32.3 kg/hm²(14.6%~16.5%)和30.4~42.1 kg/hm²(15.9%~17.6%),产量分别为5.8~6.3 t/hm²和6.6~7.5 t/hm²,N肥利用率分别为34.3%~40.5%和33.8%~39.2%;其中,CRU₂处理在早、晚稻生长季总计NH₃挥发损失量较U处理降低40.9%、38.3%,产量增加14.9%、20.9%,N肥利用率提高75.6%、96.0%。早、晚稻生长季及双季稻整个生长季CRU处理总计NH₃挥发损失量及籽粒产量与施N量呈显著线性关系。【结论】施用控释尿素显著减少双季稻田NH₃挥发损失,增加籽粒产量,提高N肥利用率,以减N 10%处理效果最明显。

Ammonia Volatilization Loss and Nitrogen Use Efficiency in Double-cropping Rice Field as Affected by Decreasing Controlled-release Urea Application Level

【Objective】The research aims to reveal the effects of controlled-release urea(CRU) application in successive years on double-cropping rice yield, nitrogen use efficiency (NUE), and ammonia (NH3) volatilization loss, and to lay a theoretical basis and develop a new method for reducing nitrogen losses in paddy field while stabilizing grain yield. 【Method】There were six treatments including zero-N (CK), urea (U) and four CRU levels (CRU1, CRU2, CRU3, CRU4, 0, 10%, 20% and 30% nitrogen reduction of CRU) in cultivars Zhongzao 39 for early rice and Taiyou 390 for late rice. Ammonia volatilization were measured by using continuous air flow enclosure method, as well as grain yield and N content.【Result】NH3 volatilization after basal fertilization and fertilizer application for tillering (U, CRU) peaked within 1-2 d, 2-4 d, lasting 8-9 days in early-rice season; peaked within 2-3 d and 3-4 d, lasting for 6-7 days for late-rice season. U application generated the highest total NH3 volatilization loss (rate) of 47.2 kg/hm2 (26.4%), and 61.9 kg/hm2 (28.7%), with grain yields of 5.5 t/hm2 and 6.2 t/hm2, and NUE of 23.0% and 20.0% for early- and late-rice season, respectively; Total NH3 volatilization loss (rate) of CRU treatments in early and late rice seasons were 22.8-32.3 kg/hm2 (14.6%-16.5%), and 30.4-42.1 kg/hm2 (15.9%-17.6%), with grain yields 5.8-6.3 t/hm2 and 6.6-7.5 t/hm2, and NUE 34.3%-40.5% and 33.8%-39.2% for early- and late-rice seasons, respectively; And CRU1 treatment reduced total NH3 volatilization loss by 40.9% and 38.3%, increased grain yield by 14.9% and 20.9%, NUE by 75.6% and 96.0% for early- and late-season rice than those of U treatment. Total NH3 volatilization loss and grain yield for early-, late-season and annual rice in CRU treatments had significant linear relationship with N application rate, namely increased with the rising N application rate. 【Conclusion】Application of CRU significantly reduced NH3 volatilization loss, and increased grain yield and NUE in double-cropping rice system, especially in CRU1 treatment.