镇江丘陵区稻田化肥氮的氨挥发及其影响因素

采用密闭室方法对镇江丘陵区典型稻麦轮作制度下的水稻插秧、分蘖和孕穗期施用尿素的氨挥发进行了测定，并对施肥后土壤pH的变化及其对氨挥发的影响进行了分析，结果表明稻田施用尿素有明显的氨挥发损失，氨挥发损失率在水稻不同生育期有很大的差异，分蘖肥的氨挥发显著高于基肥和孕穗肥，受温度、植株状况以及光照条件等因素的影响，氮挥发存在明显的年际差异。田面水的pH值在施肥后有明显的昼夜波动，而氨挥发损失受田面水pH值变化的显著影响。稻草对不同生育期施肥的氨挥发影响不同。

AMMONIA VOLATILIZATION FROM PADDY FIELD AND ITS AFFECTING FACTORS IN ZHENJIANG HILLY REGION

Ammonia volatilization was measured with the continuous air flow enclosure method in a paddy field at the Experimental Farm of Jurong Agricultural School in Zhenjiang hilly region, and its main influencing factor was investigated.The result showed that ammonia volatilization was obvious in paddy field after fertilisation with urea at the transplanting, tillering and booting stages of the rice crop.The result also showed that there was a visible ammonia volatilization which varied with the growth period and that the highest NH₃ loss rate occurred following the first top-dressing (19~26 days after rice transplanting), and the lowest NH₃ loss rate following the basal fertilisation (only 1%~3.8% of the N applied).The annual variation in ammonia volatilization was also observed due to the climate factors.An evident diurnal variation in flooding water pH and soil pH was observed after fertilization, and affected the am monia volatilization significantly.The rice straw application had a dissimilar effect which varied with the growth period.Total NH₃ loss over the whole rice-growing season increased with the N dose, but little difference was observed in the ratio of NH₃ loss to total N applied.