干湿交替对新疆绿洲农田土壤CO2排放的影响

[目的]分析不同土壤水分变化及干湿交替对土壤CO_2排放的影响,为绿洲农田土壤碳循环提供科学依据。[方法]选取新疆绿洲棉田土壤,通过室内控制模拟试验,以及用气相色谱仪分析CO_2浓度。[结果](1)与60%WFPS(土壤充水孔隙度)相比,40%WFPS对土壤CO_2排放起到了显著的抑制作用(p0.05),而80%WFPS对土壤CO_2排放无显著性影响(p0.05)。培养结束时,与60%WFPS的土壤CO_2累积排放量相比,40%WFPS的土壤CO_2累积排放量降低26%(p0.05),而80%WFPS的土壤CO_2累积排放量仅增加0.04%(p0.05)。(2)多次干湿交替循环后,干湿交替处理下的土壤CO_2累积排放量显著低于恒湿处理。在不同干旱强度处理中,重度干旱(SD)处理对土壤CO_2排放速率响应程度大于适度干旱(MD)处理,但多次干湿交替循环后,SD处理下的土壤CO_2累积排放量却显著小于MD处理。随干湿交替循环次数的增加,干湿交替对土壤CO_2排放速率的影响显著降低,特别是对土壤CO_2排放速率最高值的影响最大。[结论]在新疆绿洲棉田土壤中,干湿交替能降低土壤CO_2排放量,降低量随干旱强度的增大而增大。

Effects of Alternate Drying and Wetting on Soil CO2 Emissions in Oasis Farmland of Xinjiang Region

[Objective] To evaluate the effects of soil water change and alternate drying and wetting on soil CO₂ emissions in order to provide basis for soil carbon cycle in oasis farmland.[Methods] Soil samples were taken from oasis farmland in Xinjiang region, which was used for incubation experiment in laboratory. CO₂ concentration was analyzed by meteorological chromatograph.[Results] (1) Compared with 60% WFPS(water filling soil porosity), 40% WFPS had a significant inhibiting effect on soil CO₂ emissions(p<0.05), while 80% WFPS was no significant influence on soil CO₂ emissions(p<0.05). At the end of the experiment, compared with 60% WFPS, accumulation of soil CO₂ emissions of 40% WFPS was reduced by 26%(p<0.05), while accumulation of soil CO₂ emissions of 80% WFPS was increased by 0.04%(p>0.05). (2) After multiple wet dry cycling, soil CO₂ accumulative emissions under alternate drying and wetting condition was significant lower than that of constant moisture treatment(p<0.05). Under different drought intensity, the effect of severe drought on soil CO₂ emission rate was higher than that of the moderate drought. But after multiple wet dry cycling, the effect of severe drought on the accumulation of soil CO₂ emissions was lower than that of moderate drought(p<0.05). With the increased of drying and wetting alternation, the effects on soil CO₂ emission rate was reduced significantly, especially for maximum soil CO₂ emission rate.[Conclusion] Drying and wetting alternation can reduce soil CO₂ emissions, and the amount of reduction increases with the increasing of drought intensity in Xinjiang oasis soil.