为系统地了解不同施肥制度下各生育期氨挥发损失的程度及规律,采用密闭室法对南方红壤地区双季稻田的氨挥发进行了监测。不同施肥制度下氨挥发的变化规律基本相同,施肥后1~3d内达到峰值,随后逐渐下降,1周后无明显排放。氨挥发速率随施N量增加而增加。早季各处理氨挥发累积量基肥时为1.6~3.6kg/hm2,分蘖肥时为5.8~18.2kg/hm2;而晚季基肥、分蘖肥和穗肥时的氨挥发累积量分别为4.5~7.9、12.3~26.8和1.4~2.4kg/hm2,早、晚季氨挥发总累积量分别占其施N量的4.5%~15.3%和16.9%~32.8%。相对于不施肥处理,尿素的施用促进氨挥发,而在等氮施用量下,缺P处理通过氨挥发损失的N量较多,较高水平的秸秆和绿肥施用也会增加氨挥发量。此外,氨挥发与田面水NH4+-N浓度及水层pH之间存在正相关关系,气候条件也显著影响氨挥发量。
Ammonia volatilization from double-rice cropping field in red paddy soil was determined in a closed air-flow chamber under different fertilization systems. Ammonia volatilization under different fertilization systems exhibited a similar trend, with a peak 1 -- 3 days after fertilization and a subsequent decline, and almost no emission after a week. Ammonia volatilization rate increased with fertilizer application rate. During the early rice growth, the accumulation of N loss via ammonia volatilization after fertilization was 1. 6 -- 3. 6 kg/hmz for basal fertilizer and 5. 8 -- 18. 2 kg/hmz for fertilizer topdressed at the tillering stage, and during the late rice growth, the accumulation of N loss via ammonia volatilization was 4.5 --7.9 kg/hm2 for basal fertilizer, 12.3--26.8 kg/hm2 for fertilizer todressed at the tillering stage and 1.4--2.4 kg/hmz for fertilizer topdressed at the panicle initiation stage. The total accumulation in the early and the late rice growth period occupied 4.5%--15.3% and 16.9%--32.8% of the total of fertilizer application, respectively. Compared to the control, urea application could promote ammonia volatilization, and more N was lost through ammonia volatilization under the conditions of equal N application and zero P application. The supplement of more rice straw and green manure also showed a positive relationship with ammonia volatilization, so did NH4 +-N concentration, water pH and climate conditions(light, temperature and rainfall etc. ).