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通过恒温培养试验,研究了不同类型秸秆还田后的土壤CO2排放特征及其与秸秆C、N含量的关系,以明晰黑土区不同类型秸秆还田后的分解特征,探明还田秸秆的C、N含量对固碳效果的影响.结果表明:在61 d的培养试验中,土壤CO2排放速率随时间呈现出“下降-稳定-增大(出现‘较高值’)-下降”的过程.不同类型秸秆还田后土壤CO2排放速率随时间变化的特征存在明显差异,主要体现在“较高值”出现和持续的时间不同.秸秆类型对土壤CO2累积排放量具有显著影响,前21 d和前61 d的土壤CO2累积排放量对秸秆添加的响应不同.在前21 d,玉米根、玉米茎下部、玉米叶、大豆叶的CO2累积排放量(约160μmol·g-1)显著大于其他秸秆;而除大豆叶外,大豆秸秆61 d的CO2累积排放量均比玉米秸秆大.前21 d CO2累积排放量与秸秆含碳量的比值(CR)和秸秆的C/N、含氮量之间均呈显著的线性相关;而61 d的CO2累积排放量与秸秆的C、N含量之间不存在线性关系.综上,在还田条件下,秸秆类型对土壤CO2的排放有明显影响;大豆秸秆比玉米秸秆容易分解,但与长时间分解不同,大豆秸秆还田最初阶段的分解速率小于玉米秸秆;秸秆的C/N、含氮量只对还田最初阶段的土壤CO2排放有较大影响.
The effects of different types of straw on the soil CO2 emission and its relationship with C and N contents of straw were studied through isothermal culture experiments to clarify the decomposition characteristics of different types of straw in the black soil after returning to the field, , N content on the carbon sequestration.The results showed that in the 61 d culture experiment, the soil CO2 emission rate showed “decreasing-stabilizing-increasing (showing the higher value) -decreasing” with time The differences of soil CO2 emission rate with time under different types of straw returning were significant differences, mainly reflected in the appearance and duration of “higher value” occurrence.The straw types had a significant effect on the cumulative emission of soil CO2, In the first 21 days and the first 61 days, the cumulative CO2 emission of soil was different from that of straw addition. In the first 21 days, the cumulative CO2 emission (about 160 μmol · g-1) of maize roots, lower maize stems, maize leaves and soybean leaves, (P <0.05), but significantly higher than that of other stalks except for soybean leaves.The 61-day accumulation of CO2 in soybean stalks was larger than that of corn stalks.The ratio of cumulative CO2 emissions to straw carbon content (C0) and C / N, Nitrogen content showed significant linear correlation between; and 61 d of CO2 There was no linear relationship between product emissions and C, N content of straw.In summary, under the conditions of return to straw, straw types have a significant impact on soil CO2 emissions; Soybean straw decomposition easier than corn stalks, but with a long time decomposition , The decomposition rate of soybean straw in the initial stage was smaller than that of corn straw. The C / N and nitrogen contents of straw had a significant effect on the soil CO2 emission in the initial stage of returning straw.