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为了解黄土高原旱作农田土壤CH4排放对不同降水事件的短期响应过程,分别在冬小麦拔节期和夏闲期进行了人工模拟降水试验,对1~32 mm不同降水量模拟降水后0~72 h土壤CH4排放通量进行了观测.结果表明:模拟降水后旱作农田土壤CH4排放通量变化特征表现出两种不同的模式:低降水量(1、3和8 mm)处理为波动变化,高降水量(16和32 mm)处理呈单峰型变化.降水后72 h土壤CH4累积通量(CH4-C)与降水量(P)呈显著线性正相关(冬小麦拔节期:CH4-C=2.45P-6.09,R2=0.92,P<0.01;夏闲期:CH4-C=2.43P-4.73,R2=0.91,P<0.01).相关分析表明,土壤CH4通量与土壤含水量和土壤微生物生物量碳含量显著相关,而与土壤温度不相关.少量降水(1~8 mm)可以在短期内促进旱作农田土壤对CH4的吸收,加强土壤作为大气CH4汇的强度,然而这种促进作用也会随降水量的增大和降水的下渗而削弱.较大降水(≥16 mm)可以刺激土壤产甲烷菌活性促进CH4释放,在短期内使旱作农田土壤由单一的汇功能转变为汇源双重功能.
In order to understand the short-term response process of soil CH4 emission to different precipitation events in dryland farmland in the Loess Plateau, artificial rainfall experiments were conducted at the jointing and summer fallow periods of winter wheat. The simulated precipitation of 0 ~ 72 h The results showed that there were two different patterns of CH4 fluxes in dryland soils after simulated precipitation: low precipitation (1, 3 and 8 mm) The precipitation (16 and 32 mm) showed a single-peaked change, and there was a significant linear positive correlation between cumulative CH4-C flux and precipitation (P) at 72 h after precipitation (winter wheat jointing period: CH4-C = 2.45 P = 6.09, R2 = 0.92, P <0.01; summer leisure time: CH4-C = 2.43P-4.73, R2 = 0.91, P <0.01) .The correlation analysis indicated that soil CH4 flux and soil water content and soil microbial organism Carbon content was significantly correlated with soil temperature but a small amount of precipitation (1-8 mm) could promote the absorption of CH4 in the dry farmland soil in a short period of time and enhance the intensity of the soil as the atmospheric CH4 sink. However, Will be weakened with the increase of precipitation and the infiltration of precipitation.The larger precipitation (≥16 mm) can stimulate the production of methane Activity to promote the release of CH4, Arid Soil in the short term, the transition from a single sink function as Huiyuan dual function.