【摘要】 水稻田间实验研究了烤田期间的土壤温度、Eh、含水量和裂缝基本性质,矿质态氮以及与氮有关的酶活性的演变规律,及其对N2O排放的影响.试验表明,在水稻分蘖期间烤田,N2O有一个排放高峰,其最高值可达75 6μg·m-2·h-1.在排放高峰后,即使继续烤田,N2O的排放值也将降低.N2O排放与尿素氮肥的施用量没有明显关系.裂缝的生成,改变了N2O的日排放规律.随着烤田时间的延长,脲酶和羟胺还原酶活性呈波动变化,硝酸还原酶活性递减,亚硝酸还原酶活性极低.硝酸还原酶活性与N2O排放之间没有显著相关性.土壤中的脲酶活性与N2O日排放通量呈显著的线性正相关.在烤田期间,NO-3含量呈增加趋势.土壤中的硝态氮含量与N2O排放通量之间呈显著正线性关系.土壤中的铵态氮含量与N2O排放通量之间呈显著负线性相关.更多还原

【Abstract】 Nitrous oxide is of environmental importance because it contributes to global warming and the depletion of the stratospheric ozone layer. Soil drying is a normal technology of rice planting in South China. The studies were important and essential that environmental factors and the enzyme activity on nitrous oxide emissions accompanied the soil drying . The evolvement of the soil temperature , Eh, gravimetric soil water content, basic characteristics of cracks,ammonium and nitrate nitrogen concentration, urease activity, and nitrate, nitrite and hydroxylamine reductase activity and nitrous oxide emissions were analyzed in paddy soil drying in the rice fields experiments. The relationships among the impact factors and nitrous oxide emissions were discussed and analyzed in the experiments in the soil drying, respectively. The nitrous oxide emissions had a peak in rice tillering of soil drying. The highest nitrous oxide emission flux reached 75.6?μg·m^-2·h^-1 on the 3rd day after draining. After the emission peak, the nitrous oxide emissions began to decline even if the soil drying continued. Adding fertilizing urea （didn’t） result in the obvious difference of nitrous oxide emissions in different rice fields. The diurnal nitrous oxide emission peak appeared at 20:30 at night on cracked paddy fields, and the generation of cracks changed the diurnal nitrous oxide emission rule. Cracks appeared on the third day after drainage. Cracks in soil drying were benefited to the transferring of nitrous oxide into atmosphere, and increased the concentration of O₂ in soil and had effects on the formation of nitrous oxide by nitrification and denitrification. The activities of urease and hydroxylamine reductase fluctuated, and nitrate reducatse decreased with the time of soil drying. The activity of nitrite reductase had very low value. There were linear positive correlation between the urease activity and daily nitrous oxide emission flux, and nitrate reductase had no significant relationship with nitrous oxide emission flux. The concentration of nitrate nitrogen increased after draining. There were linear positive and negative correlation respectivly between nitrate and ammonium nitrogen and nitrous oxide emission flux.更多还原