Soil organic carbon increase via microbial assimilation or soil protection against the priming effect is mediated by the availability of soil N relative to input C

文献类型： 外文期刊

第一作者： Zhang, Futao

作者： Zhang, Futao;Wang, Qianqian;Zhang, Yueling;Yao, Shuihong;Ndzana, Georges;Wang, Qinhua;Ndzana, Georges;Hamer, Ute;Kuzyakov, Yakov;Kuzyakov, Yakov;Zhang, Bin

作者机构：

关键词： Soil organic carbon dynamics; Priming effect; Microbial anabolism; Physical protection; Microbial growth; Microbial reutilization

期刊名称：GEODERMA （ 影响因子：6.1； 五年影响因子：7.0 ）

ISSN： 0016-7061

年卷期： 2024 年 444 卷

页码：

收录情况： SCI

摘要： Labile C inputs into soils will be partially transformed into soil organic carbon (SOC) through microbial assimilation or physicochemical protection as such mineral-organic interactions and soil aggregation. The C inputs may stimulate the decomposition of native SOC, inducing a phenomenon known as the priming effect. Increasing C inputs may increase SOC content, yet the relative role of these mechanisms in controlling the magnitudes of SOC increase among soils remains unclear. Four soils differing in microbiology and N content were incubated with 13 C-labeled glucose at the amounts of 0.5 (G 0.5 ), 1.0 (G 1.0 ), and 2.0 (G 2.0 ) g C kg -1 soil for 48 days. The objectives of this study were 1) to quantify the fates of added glucose -C, the priming effect, and the changes in SOC and mineral N contents after the incubation, and 2) to identify the main mechanisms for SOC increase with the increased amount of C input and the effects of initial soil N availability and microbial composition. 13 C isotope probing showed that 19 to 26 % and 37 to 96 % of added glucose were utilized for microbial respiration and growth, respectively, after the incubation in all soils, with the glucose -C use efficiency ranging from 30 to 60 %. The remaining accounted for 4 to 37 % in all cases except for Ultisol HN at G 1.0 and G 2.0 ( - 23 % and -2%), which was confirmed as the fraction protected in soil or re-utilized by microbes via acid extraction. The soil-protected glucose -C was higher, while glucose -C use efficiency was lower with the increased amount of added glucose only in the soils with low N. Glucose addition induced a positive priming effect, a SOC increase, and a mineral N loss irrespective of soil type and addition amount. Glucose addition increased the cumulative fungal biomass in all cases and the cumulative bacterial biomass only at G 2.0 in all soils and at G 1.0 in the high -N soils. It increased the final fungal necromass only at G 0.5 in Mollisol LN and Ultisol HN and at G 2.0 in Mollisol HN and the final bacterial necromass in all cases except for the low-N soils and Ultisol HN at G 2.0 . With the increased amount of added glucose, the SOC content increased linearly and the priming effect and fungal biomass increased non-linearly, with larger magnitudes in the soils with lower N. These results indicated that glucose was quickly protected after addition and remained in the soil until soil N became a limiting factor for microbial utilization. The availability of soil N relative to input C mediated microbial growth and its controls over SOC change via the soil protection and priming effects. The carbon sequestration potential with increased input of dissolved substrates as such glucose e. g. through root exudation was likely larger in soils with lower fertility due to reduced substrate-C use efficiency and increased effect of soil protection despite an increased priming effect. Further studies are needed on more substrate types as they affect substrate-C use efficiency and soil protection mechanisms.

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