Cara Eisenpress - - Soil Health

Legendary American Soil: Red Dirt

Across a swath of the Southeastern United States, the land is covered with red dirt, a soil so iconic it ended up the name of a genre of alt-country music centered around Stillwater, Oklahoma, and featuring musicians like Bob Childers.

“You get your hands in it, plant your roots in it, dusty headlights dance with your boots in it,” Florida Georgia Line sings in the 2014 single “Dirt,” a song about the beloved red dirt roads region. In Georgia, potters make handmade bowls out of the red clay.

But red dirt has legendary status in agriculture, as well.

Red clay soil, usually ultisols in the U.S. Department of Agriculture soil taxonomy, is old soil, formed by the weathering of nearby rocks and given its hue by iron oxides as they aged in the humid climate. Though some residents resent the stains red dirt leaves on clothing and homes, many find it to be excellent agricultural soil when well-managed.

Clay Soil for Peaches

Nutrients in this soil order tend to remain in the top few inches. Clay soil holds onto both water and nutrients just below the surface, making them available to the roots of plants like famed Georgia peach trees, which thrive in the humid conditions up above the soil. Yet the soil can become waterlogged in rainy winters, then harden into impermeable clay in summer. Peach trees in Georgia prefer top soil that’s 18 to 24 inches deep with well-drained clay subsoil, according to University of Georgia Cooperative Extension.

“Peach trees are extremely sensitive to poorly drained soils,” according to the a report from the University of Georgia College of Agricultural & Environmental Sciences. “In areas of poor drainage, roots will die, resulting in stunted growth and eventual death of the tree.” Research from the University of Washington has also started to hint that soil health improves the quality of fruit.

Georgia-peaches-1

Watching Out for Low pH

The clay soils in Georgia are slightly to very acidic, according to a Soil Test Handbook for Georgia, made by the University of Georgia College of Agricultural & Environmental Sciences and the Georgia Cooperative Extension. This is because “the parent materials from which they were developed and the high annual rainfall that leaches base-forming cations such as calcium and magnesium from the soil,” the authors write. Low pH affects soil by creating nutrient deficiencies and slowing down the formation of nitrate.

Managing Fertility for Red Dirt

Ultisols have low native fertility but with the right management can be quite fertile, as shown by the agricultural success of states like Georgia, the Carolinas, and Alabama. However, years of intensive cotton growing in the 18th and 19th centuries eroded topsoil, depleting its nutrients, according to the Georgia Soil and Water Conservation Commission.

Proven regenerative techniques like planting diverse cropping systems and grazing animals have been helping to remediate some overworked parcels into productive pastureland, adding grazing days and improving forage utilization for one Northern Georgia rancher who shared his story with the Natural Resources Conservation Service. These techniques also brought more organic carbon back into the soil in order to feed a diverse microbial population.

For planting, incorporating organic matter can help clay soils like red dirt hold onto both water and other amendments, such as the lime needed to remedy the high acidity. Still, red dirt has a fairly low capacity to retain additions of lime and fertilizer, according to the Natural Resources Conservation Service.

The Stuff of Song

For many, the agricultural products of red dirt are renowned far beyond the Southeast. The area’s peaches, in particular, inspire such loyalty that those who love them won’t even eat a peach from California, a state that actually has a higher peach production. Yet changes in climate are threatening the beloved fruit, which needs frozen temperatures in the off-season to thrive.

Through the careful work of scientists and land stewards, the state of Georgia’s soil restoration efforts have largely succeeded in keeping the red dirt fertile enough for productive farming.

And the red dirt region natives’ pride continues to run deep. “You’ve mixed some sweat with it, taken a shovel to it, you know you came from it, and some day you’ll return it," Florida Georgia Line continues in its ode to the beloved home.