|ZHANG, YUELING - CHINESE ACADEMY OF SCIENCES|
|YAO, SHUIHONG - CHINESE ACADEMY OF SCIENCES|
|CAO, XIAOYAN - CHINESE ACADEMY OF SCIENCES|
|SCHMIDT-ROHR, KLAUS - BRANDEIS UNIVERSITY|
|Olk, Daniel - Dan|
|MAO, JINGDONG - OLD DOMINION UNIVERSITY|
|ZHANG, BIN - CHINESE ACADEMY OF SCIENCES|
Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2018
Publication Date: 4/1/2018
Citation: Zhang, Y., Yao, S., Cao, X., Schmidt-Rohr, K., Olk, D.C., Mao, J., Zhang, B. 2018. Structural evidence for soil organic matter turnover following glucose addition and microbial controls over soil carbon change at different horizons of a Mollisol. Soil Biology and Biochemistry. 119:63-73. https://doi.org/10.1016/j.soilbio.2018.01.009.
Interpretive Summary: Carbon contributes to several favorable soil processes, including nutrient availability, water infiltration, and biological activity. The addition of new carbon into soil as crop straw and roots or as animal manure might cause faster decomposition of stable carbon already present in the soil by promoting microbial activity. This decomposition might occur at the same time that some of the new carbon is also being stabilized in the soil, although no direct evidence exists. To distinguish these two processes for the first time, we added different types of carbon to an incubating soil. Measurements of changes in the different carbon types confirmed that stable soil carbon was being decomposed at the same time that new carbon was being stabilized in the soil, and rates of these changes varied between the topsoil and the lower soil depths. This work demonstrates the complexity of managing stable soil carbon and its interactions with microbial activity. It will benefit researchers who study the factors of carbon stability in soil or the types of carbon in soil and land managers who strive to maximize carbon content in soil.
Technical Abstract: Soil organic matter (SOM) is the largest terrestrial organic carbon pool. It may increase in low-carbon subsoils with increasing organic inputs. Addition of fresh organic materials stimulates SOM decomposition, but whether and how it may affect SOM formation is unknown. Using 13C- and 12C-enriched glucose and quantitative solid-state 13C NMR, we have separated the processes of SOM decomposition and formation for the first time. We show that SOM decomposition and formation are both controlled by microbial-substrate interaction, and separately influenced by SOM chemistry and physical soil properties. Our study provides direct evidence for structural renewal of SOM as driven by organic input in an ecosystem, and highlights that SOM turnover is ecosystem-specific. The greater potential of carbon storage in subsoils needs further investigation under various ecosystems. Our study also outlines a novel path to a quantitative understanding of SOM turnover, soil functions and the global carbon cycle.