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为定量研究有机物料还田对农田土壤N2O排放的影响,采用静态暗箱-气相色谱法对关中平原冬小麦-玉米轮作24 a长期定位施肥试验地土壤N2O排放速率和相关环境因子进行了周年观测,试验处理为对照(CK,0 kg·hm~(-2))、氮磷钾(NPK,353kg·hm~(-2))、氮磷钾加秸秆还田[NPKS,(353+40)kg·hm~(-2)]和氮磷钾加牛粪[NPKM,(238+115)kg·hm~(-2)]4个处理.结果表明观测期内,CK处理N2O排放速率较小[<2.9 g·(hm~2·d)~(-1)];施肥处理在冬小麦季施肥和玉米季灌溉后均出现排放峰,最高值分别为NPKS[113.4 g·(hm~2·d)~(-1)]和NPKM[495.0 g·(hm~2·d)~(-1)]处理.各处理N2O排放通量与土壤湿度均呈显著正相关关系(r>0.28,P<0.05).CK、NPK、NPKS和NPKM处理N2O年排放总量分别为(0.1±0.0)、(2.6±0.1)、(3.4±0.7)和(2.9±0.3)kg·hm~(-2),施肥处理排放总量显著高于CK处理(P<0.05),但施肥处理之间差异不显著(P=0.06),说明施肥促进了N2O排放,但有机物料还田未能显著增加N2O排放.各施肥处理N2O直接排放系数分别为0.72%、0.83%和0.80%,均低于IPCC缺省值1%.施肥处理中,NPKM处理的单位产量N2O排放量最低.
In order to quantitatively study the effect of organic matter return on soil N2O emission from farmland, the static dark-gas chromatography was used to observe the annual N2O emission rate and related environmental factors of winter wheat-corn rotation in the Guanzhong Plain for 24 a long-term experiment. The treatments were as follows: CK (0 kg · hm -2), NPK (353 kg · hm -2), NPK plus straw returning [NPKS (353 ± 40) kg · hm ~ (-2)] and NPKM (238 + 115) kg · hm -2], respectively.The results showed that during the observation period, the N 2 O emission rate of CK was small [ 2.9 g · (hm ~ 2 · d) -1]. Fertilization treatments showed peak emission after winter wheat season and post-maize irrigation, respectively. The highest values were NPKS [113.4 g · (hm ~ 2 · d) (-1)] and NPKM [495.0 g · (hm ~ 2 · d -1)] .N2O flux and soil moisture had a significant positive correlation (r> 0.28, P <0.05) The total annual N2O emissions from treatments with CK, NPK, NPKS and NPKM were (0.1 ± 0.0), (2.6 ± 0.1), (3.4 ± 0.7) and (2.9 ± 0.3) kg · hm -2 The total amount of discharge was significantly higher than that of CK (P <0.05), but there was no significant difference between the two treatments (P = 0.06), indicating that fertilization promoted N2O emission, Failed to significantly increase N2O emissions. All treatments direct N2O emission factor 0.72%, 0.83% and 0.80%, respectively, were lower than 1% IPCC default. Fertilization, the processing unit NPKM lowest yield N2O emissions.