Soil Carbon in Grasslands

Nashville, Ark. – While the trend to curb global warming becomes more urgent, agricultural researchers have been lending their data to the discussion. Dirk Philipp, associate professor of forage agronomy for the University of Arkansas System Division of Agriculture, said, “The possibility of increasing soil carbon stocks through grazing practices carries some promise.”

Several factors determine soil carbon sequestration that pertain to grassland agriculture. Key factors include landscape topography and the forages selected for the process. Arkansas is not generally blessed with rich soil high in organic matter, with the exception of the Delta “In areas with livestock agriculture, soils are much shallower with less total amounts of soil organic matter, prone to more drastic changes in soil water content throughout the growing season and with a less advantageous topography,” Philipp said. However, prairie-type grasslands are perfectly suited to Arkansas. Farmers today can take advantage of that information to select forage species adapted to the Arkansas climate. Philipp recommends relying more on native species when selecting forage species instead of species that are introduced from outside of the region. “Introduced forages such as tall fescue and bermudagrass are resilient and their root systems are relatively shallow to take advantage of fertilization and collect nutrients from the upper soil layer,” Philipp said. “Native grass species, however, particularly the taller ones such as big bluestem, Indiangrass, switchgrass and little bluestem, have a very deep root system that makes them nutrient frugal and water-use efficient.”

But the question remains: How does one get carbon out of the air and into the ground? “This heavily depends on the amount of generated aboveground biomass,” Philipp said. “In general, the higher the aboveground biomass, the higher the belowground biomass that at some point dies. Part of it is then converted to stable carbon compounds which remain sequestered in the soil.” All too often pastures are grazed beyond the point of a speedy recovery when farmers should be using a “take half, leave half” method. The stand of grass will recover quicker if more leaf area is left after grazing. There is evidence that rotational grazing will help increase soil organic matter, but the effect is not indefinite. Additionally, the practicality of the rotational grazing strategy greatly depends on the soil conditions before starting. Increasing soil organic matter for the long term will likely require a substantial increase in both deep- and shallow-rooted pasture species diversity and adjusted grazing management.

For more information on soil carbon, you can contact the Howard County Extension office at 870-845-7517 or find helpful fact sheets on our website at www.uada.edu.

Pursuant to 7 CFR § 15.3, the University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution. 

By Dawson Bailey
County Extension Agent - Agriculture
The Cooperative Extension Service
U of A System Division of Agriculture

Media Contact: Dawson Bailey
County Extension Agent - Agriculture
U of A Division of Agriculture
Cooperative Extension Service
421 N. Main Nashville AR 71852
(870) 845-7517
dbailey@uada.edu

The Arkansas Cooperative Extension Service is an equal opportunity institution. If you require a reasonable accommodation to participate or need materials in another format, please contact your County Extension office (or other appropriate office) as soon as possible. Dial 711 for Arkansas Relay.

Pursuant to 7 CFR § 15.3, the University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution.