太湖地区铁渗水耕人为土稻季上氮肥的氨挥发

系统地研究了太湖地区铁渗水耕人为土（黄泥土）稻田上施入的尿素通过氨挥发损失的过程和数量，以及土壤等条件对其影响，可为减少该地区稻季氮肥氨挥发损失，提高氮素利用率提供理论依据。试验应用连续气流密闭室法测定了太湖地区典型稻麦轮作制度中稻季不同施氮量下的水稻基肥、分蘖和孕穗期施用尿素的氨挥发损失，并对其影响因素（田面水中NH4^＋-N浓度、pH值等）的作用进行了分析研究。结果表明，水稻施用尿素后的氨挥发损失量占施肥量的3．7％～11．7％，其中以分蘖肥时期损失最大，其次为穗肥，基肥氨挥发损失最小，氨挥发损失主要时期是在施肥后7d内，田面水中的NH4^＋-N浓度和pH值与氨挥发量有极显著的相关关系（相关系数分别为0．791^＊＊、0．443^＊＊）。

AMMONIA VOLATILIZATION FROM NITROGEN FERTILIZER IN THE RICE FIELD OF Fe-LEACHI-STAGNIC ANTHROSOLS IN THE TAIHU LAKE REGION

The amount and process of ammonia volatilization from nitrogen fertilizer in the rice field of Fe-leachi-Stagnic Anthrosols in the Taihu Lake region were investigated.The effect of some soil factors on N loss was also studied. The purpose of the experiment was to provide basic theory to reduce the amount of ammonia volatilization loss from nitrogen fertilizer and improve nitrogen use efficiency in rice field.Ammonia volatilization loss from urea applied was measured with the continuous airflow method in the experiment and the main influencing factors(NH~ _(4)-N concentration and pH in flooded water,etc.) were also measured.Results showed that ammonia volatilization loss varied from 3.7% to 11.7% of applied N,the highest N loss occurred in the period of tillering-top dressing,lower in ear bearing-top dressing period,and the least in basal dressing period.Ammonia volatilization primarily occurred in one week after fertilization.And there was a significant correlation between the NH~ _(4)-N concentration,pH in the flooded water and the amount of ammonia volatilization(the correlation coefficient was(0.791~(**)) and 0.443~(**),respectively).