高CO_2浓度条件下农田土壤有机质的化学稳定性研究

大气CO2浓度升高显著增加作物生物量,从而使进入土壤的有机碳增加,这势必会影响土壤碳的稳定和积累。采取利用化学方法获得的具有不同化学稳定性的有机物,间接地研究大气CO2浓度升高以后通过直接影响秸秆生物量和化学成分对土壤碳变化的影响。结果显示,相对于对照处理:高CO2浓度处理使土壤经Na2S2O8化学氧化后的抗氧化部分,在LN、NN和HN水平下,分别增加16.4%、21.7%和降低3.8%;使土壤经硫酸水解后的第一组分分别降低2.2%,增加9.5%和7.5%,第二组分分别增加4.7%、17.6%和降低4.9%,第三组分分别增加7.3%,降低4.2%和2.6%。表明土壤有机质的化学稳定性有所增加,可能与高CO2浓度条件下向土壤输入的有机质量及化学组成有关,且受N水平的影响较大。

Chemical Stability of Soil Organic Matter from Field Under Elevated CO2

Elevated atmospheric CO2 concentration significantly increase crops biomass, which will input more carbon into soil to affect soil carbon stability and accumulation. Chemical techniques were used to obtain organic matter fractions with different chemical stabilities, in order to investigate the indirect influence of elevated CO2 on soil carbon based on the change of crops biomass and chemical characteristics. Compared to ambient CO2, at LN, NN and HN level, elevated CO2 increased the parts that could not be removed by Na2S2O8 (SOC) by 16.4%, 21.7% and decreased it by 3.8% after treated by Na2S2O8, respectively. After soil treated with H2SO4 hydrolysis, labile pool I was decreased by 2.2%, increased by 9.5% and 7.5%, labile pool II increased by 4.7%, 17.6% and decreased by 4.9%, and recalcitrant pool increased by 7.3%, decreased by 4.2% and 2.6% due to elevated CO2 at LN, NN and HN level, respectively. These results indicated that the chemical stability of soil organic matter increased, partly due to the change of biomass and chemical characteristics of straw added in soil and N level.