东北黑土区旱作农田土壤CO2排放规律

为研究农田土壤CO2排放规律,调控农田碳平衡,通过对东北黑土区旱作农田土壤CO2排放的定位连续观测,研究了玉米、大豆农田土壤CO2排放的季节变化规律;并估算了农田碳平衡。结果表明:1)农田土壤CO2排放通量随季节呈单峰曲线变化,7月份出现最大值;秸秆覆盖还田明显增加了农田土壤CO2排放;玉米或大豆生长发育对土壤CO2排放影响较小。2)地温的季节变化与土壤CO2排放通量季节变化规律一致,用指数方程和二次方程均可很好地模拟土壤CO2排放通量与地温之间的关系,但指数方程优于二次方程,以20cm土层地温的相关性最高,5cm土层地温的相关性最低。3)玉米、大豆农田在通常情况下为大气CO2的"汇",玉米-玉米-大豆轮作周期(3a)的碳汇年平均为4.53t/hm2,该碳汇可为固碳减排提供参考。

CO2 emission law of dry farmland soil in black soil region of Northeast China

In order to study CO2 emission law of field soil for regulating carbon balance, seasonal variation of CO2 emission of maize and soybean field was investigated by continuous observation. Taking dry farmland soil as the research object, the carbon balance of farmland ecosystem was estimated. The results showed that: 1) Farmland soil CO2 emission flux presented a single peak curve with seasonal variation. CO2 emission flux reached the maximum in July. Straw mulching significantly increased the farmland soil CO2 emission; Maize or soybean plantation had little effect on soil CO2 emission. 2) Seasonal variation of soil temperature was consistent with that of soil CO2 emission, the relationship between soil CO2 emission flux and soil temperature could be well simulated by exponential equation and quadratic equation. However, exponential equation was better than quadratic equation, the correlation of soil temperature of 20 cm was the highest, which of 5 cm was the lowest. 3) Maize and soybean fields were usually the "sink" of atmospheric CO2, the average carbon-sink of maize-maize- soybean rotation (three years) was 4.53 t/hm2.