Why Are South Dakota Corn Farmers Planting Radishes?

More and more, corn farmers are planting radishes in late summer.

One such farmer is Paul Hetland, who farms near Mount Vernon, S.D. He plants radishes—as part of a mixture of cover crops that also includes turnips, oats, barley, field peas and flax—before growing corn.

On Hetland’s farm, cover crops are part of a soil health program. After harvesting winter wheat in late July, he plants cover crops in fields with wheat stubble. Those fields will be planted with corn in spring.

“From the time we harvest our wheat until the time that we plant corn, there’s a period of about 10 months where there’s nothing growing,” he says.

“We’re finding that the microbiology in the soil needs to interact with living plant roots, so we decided to take a look at cover crops.”

Left in the ground during winter

Hetland uses cover crops as part of his crop rotation system. He’s found they are most beneficial in fields where wheat is followed by corn (after corn he’ll plant soybeans and then it’s back to wheat).

“As soon as the wheat is harvested, we get in there with our air seeder,” he says. “We want to give them as much time as we can to grow and develop roots.”

The cover crops can grow waist-high by mid-fall.

“The species that we plant all terminate by frost,” Hetland says. “Then, over the course of the winter, they break down, provide food for earthworms and other microbiology, and by spring, a lot of times most of those plants are gone.”

“Essentially, we’re just trying to build healthy soil through our cover crop use,” he says.

Improving soil health and reducing erosion

As Hetland experimented with using cover crops, he began to see a variety of benefits.

“As we started to work more with cover crops and diversify the species within those mixes, we started to understand that there were a lot of things that we can do, such as alleviating soil compaction and creating macropores to help with water filtration,” he says.

“We create tons of ‘green manure’ per acre that breaks down and helps us produce more organic matter,” Hetland says. Soil with high levels of organic matter contains more nutrients for crops.

“We’re also trying to protect our soil from erosion—wind, water and anything else that might take that topsoil and move it to another area. These cover crops act like armor, and they keep that soil in place.”

And on Hetland’s farm, cover crops provide an excellent late-season food source for wildlife. He owns and operates a hunting lodge, so the cover crops work in tandem with the acres he sets aside for habitat.

“Birds roost in those cover crops, deer feed off them, and we find they are typically very much alive with wildlife,” he says.

Improving water absorption and quality

Another advantage Hetland sees with cover crops is improved water absorption. “We want every drop of rain that falls going into the soil profile,” he says.

He’s heard some farmers say they don’t want to plant cover crops because they would steal moisture that could be used for the next year’s crop. In fact, the opposite is true. “Cover crops give back moisture. It’s like a savings account—it just holds on to that water for us.”

Keeping water in the soil where it’s available for plant use is important for many reasons. Porous soil with more organic matter absorbs water readily.

“Our goal is to never have any water leave our property either on the surface or through leeching into groundwater,” says Hetland.

“We are in an area that I would consider more arid than a lot of other parts of the Corn Belt. We just try to use that water as efficiently as we can. We don’t have the ability to irrigate or have any other forms of bringing water to our farming practice, so whatever falls out of the sky is what we have to work with.”

Hetland says safeguarding water quality is also a top priority among farmers.

“Water quality is extremely important to us as producers,” he says. “Our goal is to use the best farming practices in terms of any nutrient applications so that they go to our intended crops versus finding their way into a stream, a lake or into an aquifer, where someone might be getting their drinking water from.”

“Farmers live near and enjoy lakes, rivers and streams for everything from recreation to the water that we drink,” Hetland says. “I know for myself and any of my fellow producers, it’s a very high priority.”

Conserving soil nitrogen

Yet another benefit of cover crops relates to nitrogen. An important plant nutrient, nitrogen is often added to the soil as fertilizer.

Many farmers are working to reduce the amount of nitrogen they use through more precise application, various nitrogen management aids and planting cover crops.

Hetland explains that using cover crops allows them to fix and scavenge nitrogen. “If we have any free nitrogen after our crop is done growing for the year, we want to capture that nitrogen because those would be lost dollars. We want to keep the nitrogen on the top of the soil surface, and we can do that with cover crops.”

“Some of the cover crops actually produce nitrogen and leave it in the soil. In the fields where we plant cover crops, the next crop will be corn, which is a heavy user of nitrogen,” he says. “The nitrogen is in a stable form which is more available to the plants, so it makes a lot of agronomic sense.”

All told, cover crops are just one part of a complex agronomic management system that also includes crop rotation, reduced tillage and an emphasis on soil health.

“Cover crops are planted specifically to improve different qualities within the soil,” Hetland says, “to achieve our goal of attaining sustainability and constantly working to make our soil more productive.”

If you have any questions about farming practices such as cover crops, call the office at 605-334-0100.

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