What is the relationship between soil inorganic and organic carbon and microbial activities like? is it always linear and/or positive?
Can one provide any references? (soil organic and inorganic carbon content and bacteria population and microbial activities such as basal respiration and Dehydrogenase enzyme activity)
Thanks
The attached pdfs may provide you clear message. In general. microbes play a dual role in soil. Firstly, they act as agents for the degradation of plant residues and secondly they serve as a labile pool of nutrients. The size of microbial biomass carbon may account for 2% of total soil carbon.
Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls ( DOI: 10.1038/ncomms13630 )
Abstract: Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce chemically diverse, stable SOM. We show that SOM accumulation is driven by distinct microbial communities more so than clay mineralogy, where microbial-derived SOM accumulation is greatest in soils with higher fungal abundances and more efficient microbial biomass production. PDF enclosed..
Dear Dr. Srivastava,
Thank you so much for your answer and the article.
Hi Amin,
The correlation between soil carbon stock and the bacterial population is not always positive. It can also be negative. For instance, in soils containing very high amounts of organic matter, more water would be held. This is a bad news for the aerobic bacteria's population, which may enter a dormancy phase or decline their activities and the population can significantly decrease. Vice versa, that would be a nice news for the anaerobic bacteria's population, which can resist and easily live and reproduce in oxygen-deficient conditions leading to an increased population.
In conclusion, the correlation can also be negative depending on other players in the soil and environment and also on the bacterial species.
Good luck
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