大量沼液施灌稻田的氨挥发特征

Ammonia Volatilization from the Biogas Slurry Irrigation Paddy Field

基于沼液灌溉田间试验,采用通气法研究化肥和沼液施灌稻田的氨挥发特征及其差异性。结果表明,尿素施用处理的氨挥发速率峰值出现在每次施氮后当天或第2天,而各沼液施灌处理则在施氮后当天。氨挥发速率和累计量均随着施氮量的增加而提高。沼液灌溉田间氨挥发速率随时间的动态变化主要取决于田面水中铵氮浓度的变化。每次沼液施灌后的前7天是稻田氨挥发的关键时期。水稻分蘖初期氨挥发明显高于其他时期的。等氮量沼液施灌处理的平均氨挥发速率为(1.48±2.08)kg/(hm2.d),累计量为(51.00±4.46)kg/hm2,全生育期氮素损失率(14.90±1.65)%,分别是尿素施用处理的5.1,3.0,6.4倍。因此,若以等氮量的沼液代替尿素不仅存在稻田供氮不足的风险,而且增加了氨挥发对生态环境产生不良影响的可能,这需要在沼液广泛应用于水稻生产的过程中特别关注。

In situ field experiment combined with venting method was conducted to study the ammonia volatil- ization from the biogas slurry （BS） and chemical fertilizer applied paddy field and their difference. The field experiment designed four treatments with three replications according to applied nitrogen （N） quantities, i. e. , 270 N kg/hmz （1-F） from urea, and 270 （I-B）, 540 and 1 089 N kg/hm^2 from BS. The amount of BS or fertilizer for each treatment was finished for application in three times with ten days intervals. The results showed that the peak ammonia volatilization rate at CF and each BS applied treatment plot appeared on the first or second day and the first after N application, respectively. The temporal dynamic of ammonia volatili- zation rate was mainly dominated by the ammonia concentration in the flood water. The period within seven days after N application and the early stage of tillering （i. e. , the second time for nitrogen application） was the critical time to control ammonia volatilization in paddy field for each N application process and whole rice growth period, respectively. Ammonia volatilization rate and accumulative amount were both increased with the applied N quantity. The average ammonia volatilization rate was （1.48±2.08） kg/（hm^2· d）, accumula- tive amount was （51.00 ± 4.46） kg/hmz and resulting nitrogen loss rate was （14.90± 1.65）% at the I-B treatment plot was 5.1, 3.0 and 6.4 folds of that at 1-F treatment plot, respectively. The risks on the N supply deficiency for rice growth and the environmental pollution resulting from the increased ammonia volat- ilization, therefore, should be held the attention to replace the urea with the BS as the N source for rice culti- vation.