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Corn+Soybean Digest

What Cover Crops Can Do

They’re just one tool this Indiana farmer uses to guard topsoil and boost soil health.


During 2012’s long, hot summer, Roger Wenning got a firsthand look at how a little soil residue can go a long way to add resilience to a crop. On May 14, the Greensburg, Ind., farmer no-tilled corn into a field that had been in a ryegrass/crimson clover cover crop over the winter. Since this was a high population study, he used a twin-row planter to seed at a population of either 39,000 or 45,000 seeds/acre.

Then it quit raining in southeast Indiana. The field received only 0.64 in. in May, then no more measurable precipitation until July 18, when it caught nearly an inch of rain. “There was a lot of heat right around pollination time,” Wenning recalls. “We went out to check the field and were shocked when we found that every stalk had an ear, and the ears were filled out well.”

When plots were harvested, the weigh wagon showed that dry weather had given a slight advantage to the lower population plots for most of the hybrids. But the yields across the plots ranged from 120 to 180 bu./acre. “There’s no question the yields held up because of the cover crops and no-till,” Wenning says. “Soil health definitely plays a role in helping crops fight off stress.”

Soil health is the main focus at Wenning Farms, in the rolling hills and tight clay soils of southeastern Indiana. The family operates more than 600 acres in a corn/soybean rotation.

Conservation buffers are an integral part of the operation. More than 80 acres of its crop land is devoted to grass waterways, filter strips, whole or partial field blocks planted to native warm-season grasses, plus field border/quail buffer improvements. The family also operates more than 50 acres of improved timbered land. Due to the success of its conservation efforts, Wenning Farms won a Conservation Stewardship Program (CSP) contract from the NRCS  in 2010. The CSP is designed to reward the best soil stewards.

That’s a big commitment to conservation, but Wenning has a simple explanation for why he saves soil and values soil health.

“God just gave us so much soil out here, and it’s our job to take care of it,” he says. “My father started the farm, and I need to keep it as good or better than he left it. I have sons coming into the operation to farm with me; I want to keep this productive for them. And I’ve got grandchildren, so 50 years from now, I want them to have a great farm, working with healthy soils.”


Soil health quest

Wenning’s soil-health journey has been long and winding. He became part owner of the farm after high school graduation in 1976, and then was thrust into the role of decision-maker when his father died in 1987. “We knew we were losing too much soil on our hills, and we were looking at a number of things such as waterways and conservation structures,” he says. “It began to progress from there.”

Wenning experimented with no-till in the 1990s, but since he was still operating a 300-sow hog farm, he continued to use tillage to work manure into the soil. As early as the 1980s, he sowed wheat as a cover crop to control erosion. “Wheat makes great erosion control, but it doesn’t have the root system to suit me,” he says. “I started looking for a better cover crop, and eventually I came across ryegrass.”

He also decided to address drainage issues. “We started grid-tiling this tough clay ground about 12 years ago, and we began intensive soil sampling,” Wenning recalls. “We got our nutrients in line, including lime, and started expanding our cover crops.”

In 2005, Wenning closed down the hog operation. “We then decided to go 100% no-till, and over the past four years we’ve had cover crops on every acre. We somehow find a way to get them on—aerially seeding, drilling or broadcast—because I’ve seen such advantage to cover crops,” he says.

The years of efforts to improve the soil are paying off. “My earthworms are just going nuts out in the fields now, everything is so healthy,” he says. “The ground has just continually gotten mellower, yields have improved, and in years like this, crops have weathered the bad times better.”


Cover crop promoter

Over the past five years, Wenning has served on the Decatur County SWCD Board of Supervisors. He’s become a goodwill ambassador for cover crops and no-till farming in the county, hosting numerous field days and soil-health training sessions.

“Through his leadership, the Decatur County SWCD has been put on the map as a forerunner in the region and the state,” says Michael Hughes, NRCS district conservationist in Decatur County. “Wenning Farms has hosted more than 10 soil-health-related field days over the previous five years. The field days include two NRCS training sessions and a FSA district tour in 2007. Roger also serves locally by mentoring and advising new adopters of soil health practices.”

For Wenning, such leadership just goes with the territory. “I felt that some of my duties were to help inform people, so I planted cover crops in small plots,” he says. “This was something I could do, not only to help me learn, but also help the neighbors and anyone else interested in soil health. Then we started holding field days, digging soil pits and checking roots to see how these cover crops worked. We’ve had as many as 15 species of cover crops planted in small plots, as well as mixes.”

He’s planted many varieties of ryegrass to see which ones overwinter the best. Ryegrass is one of Wenning’s favorite cover-crop species. “It has a strong root system that will go deeper into my hard clay soils. We often find ryegrass roots over 6 ft. deep in soil pits.”

He’s now evaluating ryegrass in mixtures with species such as crimson clover and oilseed radish. “Crimson clover has a little different root system that helps to break up the soil,” he says. “It also feeds the ryegrass some nitrogen throughout the winter and corn nitrogen the following year.”

He’s also experimented with radishes’ soil-building properties. “On the ground I own, I have used cover crops long enough that I don’t use very many radishes. I think they are good in a mix to help break up a hardpan, but you need ryegrass to get the roots started through it. Then the radish roots will follow.”

Building soil health is as much art as it is science. “It definitely requires a systems approach,” Wenning points out. “It’s not just no-till or cover crops that gets it done. There is a whole list of things we have to do right to get the soil healthy. We still have a long way to go, but we are definitely seeing improved yields. I don’t have the best dirt to start with, but I’m making it better.”

The value of healthy soils was driven home when Wenning rented a farm about 30 miles from farm headquarters. “Now that we are getting our soil health right, our farm has typically averaged better than 200-bushel corn. The same soil type on the farm we rented only produces two-thirds as much. This really showed me what soil health is worth.”

Wenning puts a lot of effort into tracking the impact of management changes on yields. “We are always evaluating the things in the field,” he says. “We do fungicide checks, we look at population and nitrogen rates on corn. I set a flag when we change soybean varieties.

“I yield check just about everything we do in order to see what works best,” Wenning says.


Stewardship payoff

Wenning goes the extra mile to manage crop nutrients to “keep nutrients here on our own property,” he says. “That’s done in various ways.

“We band our fertilizer, and our cover crops sequester nitrogen and phosphorus so they don’t flow out of our tile lines. Waterways keep our soil here and keep it from clogging rivers; filter strips take out any nutrients and pesticides before they enter surface water. We are in the Mississippi River basin, so holding our nutrients in place helps protect the Gulf of Mexico hypoxia zone.”

Much closer to home, the Wenning family enjoys the payoff of environmental stewardship. They take time to enjoy nature at a pristine pond on their farm, surrounded by native grasses and tall timber.

It’s not uncommon to find a number of Wenning’s extended family, which now includes four grandchildren, sitting around the fire pit or fishing at the family hideaway. For Roger, the payoff for being a good steward of the land is very personal.

“If our topsoil goes down the river, it is gone forever,” he says. “I’m looking to the future. The grandkids are my life now. We’re taking care of it for them.”

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