20 Story Idea? Email Paul.Nolan@Farms.com Better Farming | April 2024 Carbon Sequestration Farmers are sometimes criticized in environmental sustainability conversations, but soil carbon sequestration is one opportunity to turn that around. Carbon sequestration is the removal of carbon, in the form of carbon dioxide, from the atmosphere, where it will then be stored in another form, often in soil or plants. Some producers are now seeing that in addition to improving public perception of the industry, managing farmland to increase soil carbon also benefits crop and pasture productivity, drought resilience, and erosion. How does soil store carbon and how can farmers reap the benefits? What is carbon sequestration? There are a few ways that carbon is stored. It can be stored in soil or plant material, and can be organic or inorganic, and living or dead. Cedric MacLeod, executive director of the Canadian Forage & Grassland Association, says that the process of carbon storage involves the interaction of a number of factors. “It’s a complex interaction between plants, soil, and the sun,” explains MacLeod. “Photosynthesis generates sugars, and plants use carbon and put it into their roots. When a plant dies, the roots stay behind, and that becomes organic matter through an interaction with many microscopic living creatures within the soil structure.” MacLeod also notes that there is an equivalent amount of plant below the ground as what can be seen aboveground. “A corn plant grows up to maybe 14 feet tall. There’s an equivalent amount of plant below-ground as there is above,” says MacLeod. “If you consider a 22-tonne corn silage crop and all that biomass that’s generated and harvested and put into a bunker silo, that same amount of plant material is still left behind under the soil surface and that carbon drives microbial function. They chew on the roots and mineralize the material and turn it into organic matter, which will go into the next crop – and whatever is left behind contributes to carbon sequestration long-term.” Dr. Rafael Santos, associate professor in Environmental Engineering at the University of Guelph, and Dr. Emily Chiang, an associate professor in the School of Engineering at the U of G, explain that carbon can also be sequestered as organic or inorganic carbon. “There are different types of carbon in soil and different ways to store them,” says Santos. “We work with inorganic, but there’s also organic carbon. They both occur in soils, but some soils will have more organic carbon and less inorganic carbon, and vice versa. There are ways that you can interfere to store carbon or ways you can manage your land to store more carbon. They tend to be complementary, so it can be all of the ‘THE BEST MANAGEMENT SYSTEMS FOR SOIL CARBON ARE THE ONES THAT WE DON’T TOUCH.’ OPPORTUNITIES IN CARBON SEQUESTRATION By EMILY CROFT Emily Croft photo Minimum or reduced tillage systems avoid disturbing root systems and introducing oxygen.
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