Unlike cover crop growth in more receptive Midwest soils, northeast Arkansas farmers Brad Doyle and Joyce Berger Doyle face a challenge to find species that can thrive in their clayey hardpan soils better suited for rice and ducks.

Given their agronomy, soil and plant breeding research backgrounds, the Doyles understand the need for more cover crop research in their watershed area and how to conduct accurate tests. They developed a scientifically replicated test plot with 45 different cover crop species, combinations and seeding rates.

Three weeks after seeding his cover crop research plot after soybean harvest, Brad Doyle rates the growth of 45 different species mixes.

“We currently don’t see a lot of cover crops in this area. Our goal is to determine the right species and blends, the right seeding rates, and a better understanding of biomass amounts that can reduce early weed growth while capturing carbon and recycling nutrients,” Brad Doyle says. “Most importantly, we plan to use this plot as an education tool to encourage and expand cover crop adoption among farmers in this watershed.”

To help expedite this effort, the Doyles were awarded a 2020 Conservation Demonstration Grant from the American Soybean Association (ASA), funded by the Walton Family Foundation. They were one of three farm operations to receive a cost-share grant this past fall to demonstrate new next-level conservation practices. ASA and Walton Family Foundation Conservation Champions and ASA’s Conservation Legacy Award winners from the past five years were eligible to apply for the grant.

Finding a cover crop fit

Being conservation-minded, both Brad and Joyce are very concerned about their soil’s long-term care and quality. Their livelihood depends on this challenging Mississippi Alluvial Plain soil. “My parents, George and Elise, started a seed business on this land in 1975, taking over Berger Farms from my grandfather, who moved here from Iowa. As the second-generation plant breeder here at Eagle Seeds, we believe our investment in continued soil improvement can help us pass a better legacy on to our son, and help our customers improve as well,” Joyce says.

Investing in soil and water conservation is a proud legacy in the family. Joyce’s father, George Berger, pioneered a Tailwater recovery system in the 1980s to use less water from wells. He took 100 acres out of production, built a reservoir and a series of canals to capture and save all the rainfall for their farm. “In turn, we pump that reservoir water back to the fields for irrigation during the summer, and supplement or even replace our groundwater, so there are big savings there,” Brad adds.

The Berger Farms benefit from irrigation canals between their farm fields and a 100-acre reservoir that was pioneered and built back in the 1980s by George Berger.

Given autumn rains that can saturate soils—causing combines to rut-out rice and soybeans during harvest—the Doyles know they need cover crop species that can handle wet roots. Such weather also made Brad realize he wanted a shorter season soybean for this cover crop research plot to achieve planting and growth success.

The seeding opportunity window can be pretty small in the fall, given flat fields with little internal drainage that rely mostly on slow surface drainage into a canal system. “I seeded some early soybeans to make sure I could harvest early and get the cover crop trial planted,” he added.

Early cover crop growth

Following an early October soybean harvest, Brad drilled 45 different 5x20-foot cover crop seedings in a furrow-irrigated one-acre plot, replicated and randomized like their crop plot trials. “We included cereal rye, black oats, wheat, triticale, numerous brassicas, annual and perennial clovers, Austrian winter peas and hairy vetch—seeded in different combinations and seeding rates to try a little bit of everything,” Brad says. “We also consulted Arkansas State University cover crop authority Steve Green, who gave us two local species blends for seeding ahead of soybeans (cereal rye, purple top turnip) and rice (cereal rye, clover).”

The cover crops emerged by October 13, exhibiting good growth by October 30 (see photos). “After one month, the biggest difference I see now is excellent growth with the cereal grains—rye, triticale, wheat and black oats. We’re also seeing some good biodiversity of our mixes come through, some brassicas, clovers and peas,” he adds. The plots also show some volunteer soybeans, which will die out once the hard frost arrives.

A late-October sunrise shows good cover crop growth following soybean harvest. This research plot on the Berger farm near Wiener, Arkansas aims to showcase soil benefits in a soybean-rice rotation.

Examining potential benefits, challenges

As a trained agronomist and crop consultant, Brad is excited about this discovery plot to determine what works best and what is the most economical. “If we can achieve cover crop growth like some of these plots to reduce early Palmer pigweed populations, that could save herbicide input costs.”

He likes the concept of adding living roots after a cash crop harvest. The goal is to improve soil health and organic matter over time—perhaps even recycle some nutrients—as long as the cover crop can be terminated to allow successful cash crop planting and growth. “If the soil can improve and hold some water during dry spells, then we could irrigate less and save money,” Brad says.

With possible carbon market income looming on the horizon, the Doyles will use a forage harvester on some of the plots to measure biomass amounts by species mixes, along with root mass examinations to help understand carbon sequestration potential.

Brad and Joyce understand there will be challenges. “We need to see how it changes our current operation, tillage practices and planting dates. Do we plant green? Will aerial seeding work? Will migratory geese feast on cover crops? Do we terminate the crop, and when? There's a lot of unanswered questions that we need to figure out,” he says.

Expanding local cover crop trials

Any new practice like cover crops must fit into current agronomic practices to be successful, and it won’t take off overnight. “As a plant breeder, I realize our results will be from one year, one environment, but we will have replications and combinations to start learning which cover crop species work for this area,” Joyce says.

The Doyles hope to expand cover crop tests in 2021 by taking their trial successes to the next level. “We’re confident we can line up more farmers to take what we learned and apply it to their operation, given the confidence from our research efforts,” Joyce adds. “And we’re thankful to ASA and The Walton Family Foundation for helping us research and develop a cover crop fit for these challenging soils.”

ASA is proud of its conservation legacy and partnership with The Walton Family Foundation. The Walton Family has a long legacy of love for the outdoors. This Mississippi River effort, part of its 2020 Environment Strategic Plan, aims to work with organizations like ASA to align policy and market incentives to encourage farmers to adopt practices that improve water quality, improve soil health and reduce pollution across the basin.

The scientifically designed and replicated one-acre cover crop research trial near Wiener, Arkansas has 45 block (5x20-ft.) trials of cereal rye, black oats, wheat, triticale, numerous brassicas, annual and perennial clovers, Austrian winter peas and hairy vetch mixtures.