The resilience of soil to man-made changes, such as global warming, depends primarily on soil quality and soil organic carbon. Unfortunately, the past few decades have borne witness to a loss in soil carbon. This can be detrimental to the world’s food production and will only become worse as the climate changes. 

Nurturing the soil so that it can capture and store more carbon is therefore essential. Researchers from the Department of Agroecology at Aarhus University are taking a holistic approach to the problem in a new four-year project that has received 2.8 million kroner from the Independent Research Fund Denmark. 

In this project, the researchers will study the drivers of soil resilience from both soil-physical and soil-microbial approaches. 

- Some researchers focus on genetic and functional diversity of the soil microbiota while others focus on the physical and chemical aspects. It is critical to consider how soil physical, chemical and biological properties, in unison rather than in isolation, drive soil carbon storage, says the leader of the new project, researcher Emmanuel Arthur from the Department of Agroecology at Aarhus University.  

The soil and its microbiome will be elucidated

Current technology and management practices focus on reducing soil disturbance and enhancing soil carbon input with the aim of improving the soil’s capacity to capture and store carbon. The soil microbial community – its microbiome – is crucial to understanding the soil carbon cycle and can be used as a climate change indicator. 

But which are the key components in the soil microbiome that are critical for carbon sequestration? To identify the key components, the researchers will take a holistic approach to studying microbe-soil interactions. 

The researchers aim to identify how soil management and climate conditions influence soil microbial communities and study the feedback effect on soil carbon sequestration. With the knowledge gained in the project, they aim to define the minimum physical and chemical conditions that are necessary for the development of the soil microbial communities that are critical to carbon sequestration. Finally, the researchers will investigate if inoculating the soil with the relevant microbes can boost carbon sequestration in soil that is lacking in organic carbon. 

Microbial tea party

The actual experiments will use existing field experiments in a very wide range of environments in Greenland, California, Rothamsted and Denmark. These research sites represent variations in temperature, humidity, soil texture (from sand to clay), organic matter quality, input and quantity, and soil carbon sequestration capabilities.    

Part of the project will be to study decomposition of organic matter. This is where teabags enter the scene! In order to collect uniform decomposition data across the different ecosystems, two commercial tea types with different decompostability will be buried in the experimental soil right after sowing. Samples will be taken at pre-defined intervals in order to assess the potential for degradation and stabilisation of plant material as an index of carbon sequestration capacity – the so-called Tea Bag Index. 

Based on results from the field experiments, the researchers will select appropriate culturable microbial communities essential to soil function and test them in the laboratory and under various field conditions with a wheat crop for two seasons. 

For more information please contact

Researcher Emmanuel Arthur, Department of Agroecology, email: emmanuel.arthur@agro.au.dk, telephone: +45 8715 7734