菜地氨挥发损失及影响因素原位研究

In-situ Measurement on Volatilization Loss of Ammonia in the Vegetable Field and Its Influencing Factors

为获得菜地氨挥发通量和氨挥发损失率,并探讨其与环境影响因素之间的关系,于2009年1月～2009年5月,采用由风洞系统-大气气态污染物连续收集与在线分析装置和离子色谱联用组成的、时间分辨率为15min的氨挥发在线测定系统,用模拟试验方法对菜地(蔬菜上海青和生菜)施用尿素氨挥发特征进行研究.结果表明,系统氨气收集效率为(92.6±3.4)%;以施肥后连续采样15d的氨累积挥发量作为总挥发量,前12d的累积挥发量平均占总挥发量的(85.4±5.2)%.上海青撒施基肥和撒施追肥的氨挥发损失为23.6%和21.3%,生菜穴施基肥和撒施追肥的氨挥发损失率为17.6%和24.0%.菜地氨挥发主要发生在施肥后2～3周内,氨挥发通量与施氮量明显正相关,而氨挥发损失率与施氮量负相关.总体趋势上,氨挥发通量与土壤温度(r=0.041,p<0.05)、空气温度(r=0.049,p<0.01)明显正相关,与空气湿度、土壤水分相关性不明显.温度是影响菜地氨挥发的主要因子.

In order to obtain ammonia volatilization flux and volatilization loss rate in the vegetable field and investigate their relationship with environmental factors,an on-line monitoring system was used to measure the ammonia volatilization in the vegetable（Brassica rapa L.and lettuce） field after urea application during January to September,2009.The system included a wind tunnel system,a gas collector and an online analyzer system with ion chromatography.The time resolution of measurement was 15min.The recovery of the system was（92.6 ± 3.4）%;the accumulated ammonia volatilization within 15 d continuous sampling after fertilization was regarded as the total loss.The accumulated ammonia volatilization of 12 d continuous sampling after fertilization accounted for（85.4 ± 5.2）% of the total volatilization.The ammonia volatilization loss of broadcasting basal dressing and top dressing for Brassica rapa L.were 23.6% and 21.3%,respectively.The ammonia volatilization loss of holing basal dressing and top dressing for lettuce were 17.6% and 24.0%,respectively.The ammonia volatilization in the vegetable field mostly occurred in the first 2-3 weeks after fertilization.The ammonia volatilization flux had significant positive correlation with the nitrogen application rate,while the ammonia volatilization loss rate had negative correlation with the nitrogen application rate.The ammonia volatilization flux was positively correlated with the soil temperature（r = 0.041,p 0.05） and the air temperature（r = 0.049,p 0.01）,while not significantly associated with the air humidity and the soil moisture.Temperature was found to be a main factor influencing the ammonia volatilization in the vegetable field.