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采用静态箱法研究了黄淮海平原典型农田土壤CO2排放通量的日变化、季节变化特征,分析了土壤温度、水分对土壤呼吸的影响;并利用反硝化-分解(DNDC)模型定量化研究了根呼吸对土壤总呼吸的贡献。结果表明,在作物生长季节内棉花地、休闲地和冬小麦/夏玉米地土壤CO2排放均表现出明显的季节变化规律。土壤CO2排放季节变化的总体趋势是夏季高、其他季节低,与对应气温的动态变化基本一致。冬小麦/夏玉米地土壤CO2排放通量高峰值为2324mg·m-2·h-1,棉花地为1111.9mg·m-2·h-1,休闲地为436.07mg·m-2·h-1。土壤CO2季节性排放受温度的影响最大,其中与5cm地温的相关性最好,与土壤湿度的相关性不太明显。同一种种植模式施氮量高的处理CO2平均排放通量大于低的处理。同时根据DNDC模型估算,玉米根际呼吸对土壤呼吸的贡献最大,为91%～95%,棉花和冬小麦根际呼吸比例分别约为70%和80%。施氮不仅影响土壤微生物的呼吸而且还影响到根系呼吸。
The daily and seasonal variations of CO2 flux over the typical farmland soils of the Huang-Huai-Hai Plain were studied using the static tank method. The effects of soil temperature and moisture on soil respiration were analyzed. The effects of soil temperature and moisture on soil respiration were also studied. The results of quantitative analysis using the denitrification-decomposition (DNDC) model Root Respiration Contribution to Total Soil Respiration. The results showed that soil CO2 emission in cotton, fallow and winter wheat / summer maize fields all showed obvious seasonal variation during crop growth season. The overall trend of seasonal variation of soil CO2 emissions is summer high and low in other seasons, which is basically consistent with the dynamic changes of corresponding temperature. The peak CO2 flux of soil in winter wheat / summer maize was 2324mg · m-2 · h-1, that of cotton was 1111.9mg · m-2 · h-1, and that of fallow was 436.07mg · m-2 · h-1 . Soil CO2 seasonal discharge is most affected by temperature, of which the correlation with 5cm ground temperature is the best and the correlation with soil moisture is not obvious. In the same cropping pattern, the treatment with high nitrogen application rate is more than the average discharge flux of CO2. According to the DNDC model, the rhizospheric respiration of maize has the largest contribution to soil respiration, ranging from 91% to 95%, and the rhizospheric respiration rates of cotton and winter wheat are about 70% and 80% respectively. Nitrogen application affects not only the respiration of soil microorganisms but also the root respiration.