Drawing Carbon Out of Air Into Soil, Part 1 – Carbon Farming


Many are talking about carbon farming: use of agriculture to build soil carbon and simultaneously draw carbon out of the air. Many are making hyperbolic-sounding claims about the potential of carbon farming. What really is the potential? How do we enable carbon farming to achieve a dramatic carbon redistribution from air to soil?

InsideClimate News highlights five practices to help sequester carbon in soil:

The Carbon Cycle Institute calls out over 25 measures for landowners and farmers to promote carbon storage. These measures should not look new. USDA NRCS has been promoting several of these practices for decades. Some avoid wind and water erosion as direct carbon loss, like windbreaks/shelterbreaks and riparian restoration. Others help actively build carbon in the soil, like multi-story cropping.

In terms of potential, 2% soil carbon is often referenced as a carbon level in soils. That’s 20,000 ppm. Compare that with the 410 ppm in the atmosphere, and the 60 ppm we’re told we need to draw out of the atmosphere, and you clearly see the orders of magnitude of greater potential concentration in soil, even if the soilsphere is smaller than the atmosphere.

Discussion of quantity is not sufficient, as we need to talk about rates of sequestration. How quickly can we put carbon back into the soil through these practices? Studies suggest 1.6 – 3.2 metric tons of carbon/acre/year from perennial agriculture. Marin Carbon Project reports roughly 1 ton/acre/year from compost application to grasslands. Perhaps the seminal work on the topic, the Carbon Farming Solution by Eric Toensmeier details carbon sequestration potential among many crops, climates and landscapes.

Tools to help gauge the impact of farming and ranching include COMET-Farm, allowing farms in the U.S. to provide an array of inputs and details on their soil type and management techniques to get estimates on the greenhouse gas benefits of their practices.

There is a greater awareness now of the opportunity to shift significant portions of agriculture from a problem to a solution, from a greenhouse gas source to a carbon sink. That solution is worthy of serious investment by food processors, government agriculture agencies, the investor community and, of course, farmers. Forums like the Regenerative Earth Summit and NoRegrets Initiative are working on those fronts, but much more work is needed. The business case is there for everyone involved, if there is collaboration through the entire supply-chain (or supply-cycle – value from customer comes back to the farm) to make it happen.