Soil carbon capture benefits farmers

AMES, Iowa – It is generally accepted that the earth’s carbon cycle was more or less in balance until the late 1880s, but that the world’s carbon dioxide levels have increased over the last century.

Although doubt remains regarding the cause(s), there is general agreement that human activity is responsible for at least some of the increase in carbon dioxide levels.

One thing’s clear. Regardless of the cause, we do know that emissions to the atmosphere from power and industrial plants and vehicles can contribute to an increase in carbon dioxide in the atmosphere.

Mahdi Al-Kaisi, soil management specialist, Iowa State University Extension, said soil conservation practices can improve carbon sequestration by capturing and storing carbon dioxide, possibly creating a future market for farmers to help manage the earth’s carbon sequestration.

Al-Kaisi said the concept is real, and Iowa producers should be engaged in more dialogue about the issue.

“The idea is to remove carbon dioxide from the atmosphere by ‘storing’ it in the soil. In other words, companies that release large amounts of carbon will pay farmers to ‘sequester,’ or store it,” Al-Kaisi said.

How it works. How does carbon sequestration work? “Carbon can be stored by trapping carbon dioxide within plants. The more plant volume produced, the more carbon dioxide is required,” said Al-Kaisi.

“Managing crops and farmland in ways that reduce conditions that break down plant residues (letting plant material decompose more slowly and naturally) helps, too. And reducing soil erosion keeps carbon trapped in the soil as well.”

When it comes to carbon sequestration on farms, there is no single practice that works and no prescribed set of practices works everywhere.

Al-Kaisi said the target should be to improve soil organic matter and soil function everywhere on the farm – croplands, pastures and woodlands.

Strategies. Al-Kaisi said recommended practices include some familiar strategies and some not so familiar.

“Using high residue cover crops and crop rotations (such as adding oats and hay to a corn-soybean rotation) can create larger volumes of plant materials and store more carbon in the soil.

“Less soil disturbance means lower organic matter losses. Some of the best candidates include a high-biomass crop rotation and cover crops, residue management (mulch-till, no-till, strip-till), compaction prevention and rotational grazing.”