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为研究保护地土壤N2O排放通量特征,于2009年8~12月,在河北辛集不施氮(N0)、当地习惯施氮(N900)及减量施氮(N675)处理下的秋冬季番茄保护地土壤上使用静态箱采集、气相色谱仪检测的方法测定了土壤N2O排放通量。得到以下研究结果:灌溉施肥后,各处理N2O平均排放通量与表层土壤硝态氮含量呈极显著正相关关系。灌溉施肥后7 d内是施氮处理土壤N2O主要排放期,其排放量占当季总排放量的55.9%~59.8%;高峰值一般出现在第3~5 d,此时的土壤含水量对硝化、反硝化作用都较适宜。8~10月份由于温度较高,N2O排放通量明显高于较冷的11~12月。8~10月份施氮是影响保护地土壤N2O排放的主导因素,减少施氮量显著降低了N2O排放量;之后温度是主导因素,此时N2O排放量受追施氮量的影响较小。经估算,保护地秋冬季番茄不同施氮处理N2O总排放量的大小顺序为N900(N 5.304 kg/hm2)>N675(N 3.616 kg/hm2)>N0(N 0.563 kg/hm2),差异显著,N675比N900处理降低了31.8%的N2O排放量;N675和N900处理的N2O排放系数分别为0.45和0.53。
In order to study the characteristics of N2O fluxes in the protected soils, from August to December in 2009, the autumn and winter tomato plants under N0, N900 and N675 treatments in Xinji of Hebei Province, Soil samples were collected by static box and analyzed by gas chromatography (GC). The soil N2O fluxes were measured. The results of this study are as follows: After irrigation and fertilization, the average fluxes of N2O in each treatment had a significant positive correlation with the content of nitrate in surface soil. Within 7 d after irrigation and fertilization, the main N2O emission period of N application was soil nitrogen, accounting for 55.9% -59.8% of the total emissions in this season. The peak value generally occurred on the 3rd and 5th d, and the soil water content at this time was Nitrification, denitrification are more appropriate. From October to October, due to the higher temperature, the flux of N2O emission was obviously higher than that of colder from November to December. Nitrogen application from August to October was the dominant factor affecting N2O emission in the protected soils. Reducing the N application rate significantly reduced the N2O emission. After that, the temperature was the dominant factor, and the N2O emission was less affected by the nitrogen application rate. It is estimated that the total N2O emission of different N treatments in autumn and winter in protected areas is N900 (N 5.304 kg / hm2)> N675 (N 3.616 kg / hm2)> N0 (N 0.563 kg / hm2) N675 reduced N2O emissions by 31.8% compared to N900 treatment; N2O emission factors for N675 and N900 treatment were 0.45 and 0.53, respectively.