施用尿素对温室内NO_2和NH_3气体积累的影响

采用室内试验方法研究了尿素引起的土壤pH变化及其对氨挥发的影响，同时利用被动采样法测定了模拟温室箱中施用尿素所造成的NO2和NH3浓度变化趋势。结果表明，在短期内施用尿素能明显升高土壤pH，并增加土壤的氨挥发，NH3释放在较短的时间内达到最大，以后逐步下降。施用氮肥的模拟温室箱中NH3、NO2浓度明显高于未用氮肥的状况。光照、温度对大棚内NO2和NH3的浓度影响非常明显，晴天和高温环境易于积累这两种有害气体。

Effects of Applied Urea on Accumulation of NO2 and NH3 in Atmosphere of Greenhouses

Greenhouses are almost closed and their environmental problems beg a n to emerge as vast use of nitrogen fertilizers and the low utilization rate of fertilizers by plants.In the present investigation, both laboratory and field experiments in greenhouses were carried out to study: short-term changes of so ils pH and volatilization of ammonia by fertilizing urea. The results showed tha t in 2 types of soils by fertilizing urea, pH rose first, then fell. Volatilizat ion of ammonia became greater and appeared peak value at the fourth day after ap plication of urea.The order of ammonia volatilization intensity was alluvial v egetable soil>red soil. The reason for this difference was related to soil facto rs such as pH, CEC, OM, urease activity.In addition, the accumulation of NO2 a nd NH3 in atmosphere of simulative greenhouse induced by applied urea was invest igated. NO2 and NH3 concentrations were measured by using passive sampling. Expe rimental results showed that during the short-term, applied urea increased NH3 and NO2 concentrations.The NH3 volatilization by urea treatments reached at i ts maximum in a few days, then dropped gradually. NH3 and NO2 concentrations in the simulative greenhouse treated with nitrous fertilizers were higher than that without nitrous fertilizers or outside the simulative greenhouse. The lighting and temperature affected the accumulation of NO2 and NH3 obviously. Sunshine and high temperature resulted in accumulation of two gaseous pollutants. The lighti ng and high temperature were the major factors in controlling the concentration of NO2 in simulative greenhouse.