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首页> 外文期刊>Soil Biology & Biochemistry >Soil organic carbon decomposition from recently added and older sources estimated by delta C-13 values of CO2 and organic matter
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Soil organic carbon decomposition from recently added and older sources estimated by delta C-13 values of CO2 and organic matter

机译：通过增量C-13的CO2和有机物的值估算出最近和较旧来源的土壤有机碳分解

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The production of CO2 in soil strongly depends on the availability of organic carbon (C) for microorganisms. It is obvious, that C that entered the soil recently is more easily available for microorganisms in comparison to older C. However, only very few approaches allow for a quantitative estimation of the availability of C in relation to the time it is entering the soil. We hypothesized that delta 13C values of CO2 and of soil organic matter (SOM) after a C3 to C4 vegetation change will enable to calculate the relative availability of younger (C4-derived) and older C (C3-derived) sources for microorganisms. Soil CO2 was sampled over one vegetation period at depths of 10, 40-50 and 60-70 cm at three treatments: a C3 reference (wheat), a C4/fallow (fallow after one year of maize cropping), and a C4/C4 (two years of maize cropping). Based on the delta 13C of CO2 purified from the admixture of atmospheric CO2 by the Miller/Tans model and on the delta 13C values of SOM, the contributions of younger and older C sources to CO2 and SOM were assessed. Depending on the soil depth and the presence of living roots, the contribution of younger C to soil CO2 ranged from 16 to 50%, but that to SOM was less than 5%. By comparing the contributions of older and younger C to CO2 and SOM, we found that the relative availability of organics recently introduced into the soil (C4-derived) was about 7 times higher than the availability of C stabilized in soil for longer than one year (C3-derived). We concluded that simultaneous analysis of the delta 13C values of both SOM and of CO2 allows not only for the quantification of the CO2 sources, but also for the estimation of the availability of soil C pools of different age for microorganisms.
机译：土壤中CO 2 的产生在很大程度上取决于微生物对有机碳（C）的利用。显然，与较旧的C相比，最近进入土壤的C微生物更容易获得微生物。但是，只有极少数的方法可以定量评估C相对于进入土壤的时间的可用性。我们假设C 3 到C 4 <后，CO 2 和土壤有机质（SOM）的δ 13 C值/ sub>植被变化将能够计算较年轻（C 4 派生）和较旧C（C 3 派生）源的相对利用率。在三种植被处理下，分别在10、40-50和60-70 cm深度的一个植被周期内对土壤CO 2 进行采样：三种处理方式：C 3 参考（小麦），C 4 / fallow（玉米种植一年后休假）和C 4 / C 4 （玉米种植两年后）。基于通过Miller / Tans模型从大气CO 2 的混合物中提纯的CO 2 的δ 13 C和δ 13 C值，年轻和较老的C源对CO 2 和SOM的贡献。根据土壤深度和活根的存在，年轻的C对土壤CO 2 的贡献范围为16％至50％，但对SOM的贡献小于5％。通过比较老龄和较年轻的C对CO 2 和SOM的贡献，我们发现最近引入土壤（C 4 衍生）的有机物的相对利用率约为超过一年（从C 3 衍生）稳定的土壤中C的有效性的7倍。我们得出的结论是，同时分析SOM和CO 2 的delta 13 C值不仅允许量化CO 2 来源，也可用于估算不同年龄的土壤中C微生物的有效性。

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