江苏南部地区稻麦两熟土壤中尿素的氨挥发损失

采用连续气流密闭室法研究了江苏南部丘陵地区稻麦两熟农田施用尿素后的氨挥发损失及其年际变化。结果表明，不同年份间麦田的氨挥发量（Ｎ）占施氮量的比例变化在４．０７％～１４．８％之间。尿素作不稻基肥地，氨挥发量为１．７７％～５．５７％，分蘖期为１０．７％～１６％，而孕穗期为５．３％～８．６％。无论是麦田还是稻田，施用尿素后，年际间氨挥发量相差显著。高温、长日照和低降雨量促进氨挥发。土壤水分含量对麦田的尿素氨挥发的作用可能大于温度对它的影响。稻田高郁闭度和尿素混入土壤均有明显减少氨挥发。

Ammonia volatilization from urea applied to the field of wheat and rice in southern Jiangsu Province

Method of continuous airflow enclosure chamber was used to study ammonia volatilization from urea in wheat rice rotation system in southern hilly area of Jiangsu Province.Urea at rates of 0,100,200,300 kg/hm 2 was employed with three replicates.The results showed that N loss on the wheat field was 4 07% and 14 8% of applied N in 1996 and 1997,respectively.The N loss figures from urea used as basal fertilizer,top dressed at transplanting,broadcast at tillering and booting in rice field,were between 1 77%?5 57%,10 7%?16% and 5 3%?8 6% in 1995 and 1997,respectively.The ratio of N loss via ammonia volatilization in the treatment with same rate of urea was significantly different from year to year.The high temperature,long sunshine time,and low precipitation promoted ammonia emission.However,variation of soil water content possibly played a more important role in the process than other affecting factors in wheat field.High density of rice canopy and incorporation of urea to the soil in the rice field evidently reduced N loss by ammonia volatilization.The incorporation of urea to the soil in the rice field decreased N loss.