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How Does Manganese Impact the Carbon Cycle?

Sindhu JagadammaCarbon is the foundation of all life on planet Earth and is a central component of climate, food production, and energy creation. Carbon cycling is the way carbon is recycled or moved around from the atmosphere, into organisms and soil, and back out again. Changes to each of these components have the ability to impact the carbon cycle, but the potential effects of soil composition are not well understood. Assistant Professor of Biosystems Engineering and Soil Science Sindhu Jagadamma hopes to improve that understanding. 

Plants pull carbon dioxide from the air and, through photosynthesis, convert it to plant biomass, which ultimately ends up in soil as soil carbon. Soil carbon is critical to sustainable food production, playing a vital role in soil, water and air quality. Securely storing carbon in soil is also important for reducing the concentration of carbon dioxide in the atmosphere.   

Soil composition plays an important role in soil carbon cycling. For example, manganese content in soil can impact carbon cycling by influencing photosynthesis and litter decomposition. Jagadamma’s StART project is focusing on the impact of manganese on the balance of carbon within agricultural soil systems. 

“It is really important to understand the different drivers of carbon cycling in soil in order to build healthy soils and promote sustainability,” said Jagadamma. “The role of manganese in influencing carbon decomposition is relatively unknown, especially in agricultural soils.” 

Jagadamma points out that nitrogen fertilizers may create more acidic soil, which increases manganese availability. While manganese is an essential nutrient for plants, excess manganese in soil can inhibit plant growth and lead to lower crop yields. However, a comprehensive study determining the link between manganese, carbon cycling, and the impact on crop lands has yet to be completed. 

Jagadamma’s ORNL collaborator, Staff Scientist in Environmental Sciences Elizabeth Herndon, has begun this work with laboratory and field experiments in forested ecosystems. The knowledge these experiments have generated is being used by Jagadamma’s team to extend the research into the agricultural field.  

“We are going to manipulate different levels of manganese in soil, grow plants, and see if the different levels of manganese are influencing plant growth and litter decomposition, and how it is ultimately going to influence the carbon cycle,” said Jagadamma.  

Her project, like so many others this year, was delayed due to COVID-19 precautions but she hopes to move into the experimental phase next spring. In the meantime, she and her team have focused on literature review and a lab-scale pilot study to assist in developing the most meaningful field experiment for the Spring. 

Jagadamma’s StART project will have obvious implications for agriculture. If soil manganese is altered by nitrogen fertilization and other human-induced changes, and if those altered manganese levels change soil carbon storage, cropland systems can be developed for better crop growth and carbon storage. This work will also have broader implications for global carbon cycling by helping to curb carbon dioxide levels in the atmosphere.