保护地土壤N2O排放通量特征研究

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，减量施氮比习惯施氮处理降低了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。

Studies on the fluxes of nitrous oxide from greenhouse vegetable soil

This study was conducted to determine the effect of different N fertilization rates on N2O emissions from a loamy fluvo-aquic soil in North China Plain in 2009.Fluxes of N2O were measured on greenhouse cropped with tomatoes(Lycopersicon esculentum) with split application of 675 or 900 kg/ha N from Aug 7th to Dec 25th.An unfertilized plot planted with tomatoes as control was also set up.The results indicated that total emission increased with the N application rate.The mean N2O emission rate from the differe...