New opportunity for farmers? Capture carbon and sell credits

Texas A&M AgriLife photo

An increasing awareness and concern about the environment, changes in government policy, America’s re-entry into the Paris Agreement and a robust demand for carbon offsets all point toward an appetite for a different type of agricultural crop: carbon.

“There has been an increasing amount of discussion on how to create a way for farmers to earn credits for the climate-friendly practices they have implemented or will implement on their operations,” said Joe Outlaw, co-director of the Agriculture and Food Policy Center at the  College of Agriculture and Life Sciences and economist with the Texas A&M AgriLife Extension Service, Bryan-College Station. “One of these ways is through carbon farming that would allow for the capture or sequestration of soil organic carbon, making it possible for the sale of carbon credits to corporations so they may offset their greenhouse gas emissions.”

However, many questions on the efficacy of carbon farming and its worth to the farmer are as yet unanswered. Will there be incentives to attract a sufficient number of farmers for it to work? How much trouble will it be to implement and monitor these carbon capture methods? Will some farmers benefit more than others? Will farmers be credited for the actions they have already taken to reduce greenhouse gas emissions? 

Carbon constantly cycles through planet Earth. Light energy from the sun functions as fuel for the carbon cycle — a natural process that moves carbon through our atmosphere, biosphere, pedosphere, lithosphere and oceans.

“Human activity has created the need to extract huge amounts of deeply sequestered fossil carbon in the form of fossil fuels,” explained Katie Lewis of Texas A&M AgriLife Research, a soil fertility scientist in the Department of Soil and Crop Sciences, Lubbock. “When burned, these dense forms of carbon release massive amounts of carbon dioxide.”

She said more carbon dioxide is now being released than the earth’s land-based plant life and oceans can naturally reabsorb. This excess carbon dioxide forms a blanket in our atmosphere, trapping the sun’s heat and leading to changes in the climate.  

Worldwide, soils are estimated to contain about 10 times the amount of carbon in the atmosphere — far more than what is found in normal vegetation.

“Carbon farming is seen as a way to help restore balance within the carbon cycle,” Lewis said.   “It also helps soil build a resilience to drought and increases agricultural productivity in a natural way.

“The idea behind carbon farming is pretty simple — remove excess carbon from the atmosphere and store it in the soil, where it will facilitate plant growth,” Lewis said.

Carbon farming involves implementing agricultural practices that improve the rate at which carbon dioxide is removed from the atmosphere and converted to plant material and soil organic matter. It works by applying agricultural methods such as no-till or conservation tilling for minimal soil disturbance, mulching, composting, rotating livestock and using cover crops as ways of sequestering carbon in the soil.

“Carbon loss from the soil is mainly due to the removal of plant materials that contain carbon, usually at harvest,” Lewis said. “Changes in land management can cause soil carbon increases or decreases, creating a new equilibrium. Variation in climate can also change this equilibrium. Carbon farming can be considered successful when the net amount of soil carbon captured or sequestered exceeds the amount lost.”

Lewis said to accurately estimate soil carbon storage or stocks, soil samples should be collected at a depth that will determine bulk density and organic carbon using a dry combustion method.

“Bulk density is required to convert organic carbon percentage to an actual quantity of carbon in the soil, a stock,” she explained. “The depth of sample collection will be dependent on the depth of the soil and the cropping history. Deeper depths are likely where there is greater storage potential.”

Lewis said another method of estimating carbon storage is through a modeling approach based on management practices implemented within a farming operation.

“Model outputs should then be verified using laboratory tests,” she said.

In all, the Natural Resources Conservation Service, NRCS, of the U.S. Department of Agriculture has identified at least 32 on-farm conservation practices known to improve soil health and sequester carbon. These practices also provide other benefits in relation to water retention, hydrological function, biodiversity and resilience.

“Recently, there have been discussions about creating a ‘carbon bank’ at the USDA that would buy and sell carbon credits from farmers,” Outlaw said. “The credits could then be sold to corporations needing to offset their emissions.”

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