Microorganisms are even more important for carbon sequestration than previously thought

According to a new study by researchers at Stockholm University, among others, the way different microorganisms grow after consuming organic matter, such as old plant parts, varies greatly.

– Based on previous research, we know that microbial carbon use efficiency is important to the cycle of carbon and nutrients in soils. But we have now succeeded in showing that microorganisms are of fundamental importance in explaining how and where carbon accumulates in soil – more important than all other factors affecting carbon storage. We’ve really shifted focus to soil microorganisms, Stefano Manzoni, assistant professor in the Department of Physical Geography, says in a Stockholm University news release.

Using a new calculation method, and global data on the amount of carbon stored in the soil, the researchers were able to estimate how much carbon microorganisms use for growth and how much they consume for metabolism.

The most important process

When microorganisms use carbon for their growth, it is bound up in their cells and eventually in the soil, but when it is used in the microorganism’s metabolism, the carbon and carbon dioxide are instead released into the air as a by-product. Researchers are the first to be able to assess the relative importance of microbial versus other processes on a global scale. With the new method, the researchers estimated that the ability of microorganisms to store carbon in soil is at least four times as important as any other process.

We are constantly working to bridge the gap from soil carbon measurements to creating models that can simulate dynamic changes in soil carbon over time. This study helps us by confirming that microorganisms play a major role in this process. It’s a strong case for continuing to improve models that mimic the ecology of microorganisms, says Gustav Hugelius, professor in the Department of Physical Geography and deputy director of the Pollen Center for Climate Research at Stockholm University.

Open for further studies

The results of the study indicate that more emphasis should be given to studying different types of management and care that can provide efficient use of microbial carbon. Among others, measures to increase soil total carbon sequestration with the help of microorganisms, or how different substrates combined with microorganisms affect soil storage. According to the researchers, this could improve the health of the Earth and ensure sustainable food production for future generations as well.

The article was published on Monday, June 19, 2023

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