University of Minnesota Extension

Over the past two years, it seems like few weeks go by without at least one news article or video on carbon markets in the agricultural press each week. On March 16, Dr. Anna Cates, University of Minnesota Extension State Soil Health Specialist and Jodi DeJong-Hughes, Soil Health and Water Quality Educator from University of Minnesota joined University of Minnesota Extension Crop Educator Liz Stahl for an in-depth discussion on whether carbon storage is possible in Ag production systems and the potential benefits for soil resilience (and its portfolio) by working to improve soil health. This was the eleventh episode of Strategic Agriculture 2022: Let’s talk about crops! webinars.

Carbon is one of the most common and important elements on Earth and one of the building blocks of life. Jodi DeJong-Hughes shared with the audience that carbon makes up about 58% of soil organic matter and that soils with high carbon content tend to be darker in color and more resistant to extreme rainfall, improving both infiltration and water retention. Minnesota, Wisconsin, and Iowa have soils with some of the highest organic matter content of the lower 48 states and, therefore, some of the most productive soils in the world.

“We can help conceptualize carbon storage by thinking of it like a bank account, with carbon in and out. Aboveground and belowground crop biomass left in the field after harvest can be considered “deposits”, as can manure and cover crop biomass, while soil erosion, crop harvesting (cereals, chopping, baling), tillage, residue burning, and microbial respiration can all be considered “withdrawals,” says DeJong-Hughes.

Carbon dioxide (CO2) is important for capturing energy from the sun to create the temperate environment that sustains life on Earth. Too much CO2 in the atmosphere traps too much heat, contributing to global climate change and an increased likelihood of extreme weather events such as floods, droughts, hurricanes and wildfires. Under pressure from shareholders and consumers, the boards of publicly traded companies are looking for ways for companies to become “carbon neutral”.

Carbon neutrality can be achieved by companies finding ways to streamline their own operations or buying carbon credits from others who can remove CO2 from the air. This has led to the development of carbon markets where companies can pay farmers to adopt production practices that capture (or sequester) carbon.

Ten percent of all CO2 emissions in the United States are due to agriculture, with tillage and other soil management strategies accounting for 55% of the total. At the request of the Minnesota Corn Growers Association, Jodi DeJong-Hughes and Anna Cates developed a program called “Carbon Smart” to help educate Minnesota crop growers about the carbon cycle in our cropping systems, agronomic benefits for soil health and resilience that increasing soil organic matter can provide and the promises and pitfalls associated with entering a carbon program.

DeJong-Hughes and Cates suggest that increasing soil organic matter by modifying practices such as reducing tillage intensity or adding a cover crop is slower in fields with soil organic matter content is already higher.

“If a crop grower wants to enroll in a carbon program, they might be better able to document carbon sequestration in fields that don’t have as much organic matter in the soil,” Dejong-Hughs said. .

Joining one of these carbon markets may seem like a “no-brainer” for farmers who already wanted to adopt an additional conservation practice; it would, after all, be another potential source of income from cultivated land. DeJong-Hughes and Cates urged audiences to temper expectations due to the realities associated with latitude. The farther north the farm is, the more precipitation and cooler temperatures. Cates added: “Full season crops in Minnesota will therefore have a shorter growing season to extract CO2 from the air for growth and development than full season crops further south, and will therefore tend to sequester less carbon than crops grown further south. ”

Both from a research perspective and from a carbon market perspective, it is important to be able to say correctly that carbon sequestration has indeed taken place. Without baseline measurements of soil organic carbon prior to the implementation of conservation practices, we cannot say that carbon sequestration has occurred. “Soil disturbance by tillage, planting, incorporation of fertilizers, or other field work redistributes both soil microbes and soil aggregates, giving them access to different residues and constituents soil that microbes can use for growth and development.

This disturbance leads to an explosion of CO2 loss from the soil,” says Dr Cates. Without having baseline measurements of soil organic carbon before implementing practices intended to capture carbon, we cannot be sure if carbon continues to be lost, if carbon content remains stable over time, or if carbon is effectively sequestered after adoption of conservation practices. This is also one of the reasons why most carbon markets require the collection of soil samples before adoption of the practice and at specific intervals after adoption in order for them to sell actual carbon credits. .

Cates and DeJong-Hughes answered many questions from the audience. For those who missed this session, it is now available on YouTube at: https://youtu.be/460hSVYxJns. For more information and to register to attend additional weekly sessions through the end of March, visit z.umn.edu/strategic-farming.

Source: Angie Peltier ([email protected]) and Phyllis Bongard ([email protected])