The Innovation Team of Soil Health Care of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has made a significant progress in understanding the mechanisms of  soil organic carbon increase due to the input of labile organic carbon. The results have been published in "Geoderma" (IF = 6.1, Top Journal in the field of Agriculture and Forestry Sciences, Zone 1 of the Chinese Academy of Sciences). The title of the paper is "Soil organic carbon increase via microbial assimilation or soil protection against the priming effect is mediated by the relative availability of soil N to input C"

Labile C inputs into soils will be partially transformed into soil organic carbon (SOC) through microbial assimilation or physicochemical protection. The C inputs may stimulate the decomposition of native SOC (the priming effect). Increasing C inputs increase SOC content, yet the relative role of these mechanisms in controlling the magnitudes of SOC increase among soils remains unclear.

In this study, four soils differing in microbiology and N content were incubated with 13C-labeled glucose at four concentrations for 48 days.

The fate of the added glucose, the priming effect, and the changes in soil organic carbon and mineral nitrogen were quantified. The results indicate that the added glucose was quickly protected by the soil, and this protected glucose remained in the soil until the soil nitrogen content becomes a limiting factor for microbial utilization. The relative availability of soil nitrogen to input carbon regulates microbial growth and controls soil organic carbon content through soil protection and the priming effect. The carbon sequestration potential with increased input of dissolved substrates 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.

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Dr. Zhang Futao from the IARRP is the first author, and Professor Zhang Bin is the corresponding author. Professors Hamer, U. and Kuzyakov, Y. discussed the first draft of the manuscript This research was supported by the National Natural Science Foundation of China (41930761 and 31700458) and the Sino-German Science Center (GZ 1124).

Citation: Zhang, F.T., Wang, Q.Q., Zhang, Y.L., Yao, S.H., Wang, Q.H., Ndzanaa, G., Hamer, U., Kuzyakov, Y., Zhang, B. Soil organic carbon increase via microbial assimilation or soil protection against the priming effect is mediated by the relative availability of soil N to input C. Geoderma, 2024, 444, 116861.

Original paper link: https://authors.elsevier.com/sd/article/S0016-7061(24)00090-9