"Crimp" Your Style

You'd think killing a cover crop would be easy. Maybe, if all you want to do is spray it and wait for the plants to die. Not so easy if you want to minimize chemical use, say Gail Fuller and Kevin Karr, neighbors who farm near Emporia, Kan.

For the last three years, the two have experimented together with crop rollers to kill cover crops. The devices work great if used correctly and at the right time. But if you do a bad job of killing a cover crop with a roller, you can complicate planting your cash crops, maybe even endanger yield, the neighbors say. So killing correctly is important.

"There is not a manual for it [rolling cover crops], and we are on a steep learning curve," Fuller says.

ADVANCED EXPERTISE

His cover-crop lessons began in 1997 when he started experimenting with cover crops, primarily for erosion control. He "got serious" in 2003 and, since then, has looked for the best combinations of cover crops and cash crops on his diversified 1,500-acre farm. Fuller has cattle, sheep and chickens, and plants corn, soybeans, wheat, barley, triticale, grain sorghum, sunflowers and, lately, buckwheat for seed.

Karr got into cover crops in 2009. Like Fuller, he raises a variety of cash crops on 1,500 acres.

Both men talk about cover crops like converts to a respected, but largely forgotten, philosophy. "In the beginning, it was only for erosion control," Fuller says of his use of cover crops. "My rotation was so poor, we were losing a lot of soil. I had no knowledge at the time of [the role of cover crops] in nutrient cycling, building this much nitrogen [in the soil] or the real value of the mulch. It hadn't dawned on me yet."

The two men have come a long way. Now, Fuller and Karr sit across a kitchen table and talk about things, such as carbon/nitrogen ratios in the soil, the attributes of hairy vetch and whether multispecies cover crops are worth the extra effort compared to, say, a straight regime of cereal rye.

The discussion can get intense because the two farmers have adopted cover crops as both a practice and a passion.

"Cereal rye works great in front of soybeans, but the jury is still out about using it in front of corn," Fuller says. "Sure, it makes a nice mulch, but it ties up a lot of nitrogen." What would be a better cover crop in front of corn? "Crimson clover, hairy vetch or a pea, or something like that."

Although he has come a little later to cover crops, "I plan to use cover crops anywhere I can," Karr says. "I think in the future, we are probably going to design our rotations around the cover crop. I think they are that important."

SHARED TOOLS

A cover-crop roller (also called a crimper) kills a crop by bending the plants, which causes fatal injury. Some farmers use a follow-up spray of a reduced-rate herbicide to complete the job.

Rather than each invest in crop rollers, Fuller and Karr together rented a homemade one about three years ago. After one season of ineffectual use, they decided the concept was good, but the design of that particular roller was not ideal. "There are a lot of things that needed fixing on it," Fuller says.

For one, it was too light and didn't crimp the plants enough. Also, its 20-foot length was a bit too wide for the many terraces Fuller has on his land. "It was hard to keep all 20 feet on the ground at the same time," he remembers.

In 2012, Fuller and Karr bought a 15.5-foot model from I & J Manufacturing, a Pennsylvania firm that is one of the leading makers of cover-crop rollers. This one is about 16 inches in diameter and costs about $4,500. It weighs about 2,400 pounds when empty but can be filled with water to add another 1,200 pounds.

"The first thing I would tell someone [who is buying a crop roller] is make sure you can add water to it. That extra weight makes all the difference," Fuller says.

That first year with the I & J, Karr says, "It was about a perfect kill where I rolled at the right time."

Timing is critical when rolling crops. "For it to work, the cover has to be mature, it has to be in bloom," Fuller says. But you want to catch the cover crop before it sets seeds and reproduces to compete with cash crops.

When rolling a single species cover crop that grows at the same rate, timing is relatively simple. If you grow multispecies covers, as Fuller and Karr sometimes do, it is extremely difficult -- if not impossible -- to hit all the species at the right time.

"If the cover is nice and uniform so the roller hits every plant the same, it will take care of 90% of the crop. If you have different stages, you are going to have to spray, maybe at a reduced rate. But you're going to have to spray," Karr says.

Fuller and Karr have nothing against herbicides, but they like to keep their costs low, which is a major reason cover crops appeal to them. "Ideally, we can eliminate a burndown and a preemergence [application], and just use one late post," Fuller says.

PLANT QUICKLY

Timing is equally essential for the next step: planting. "Once you roll it, you better be ready to plant the crop," Karr says. The window can be as small as 24 to 48 hours, depending on the cover crop.

If you wait longer than that before planting, vegetative matter from dead cover becomes tough and makes planting difficult.

When the mat reaches that stage, you might as well wait longer, Fuller advises. He says after another 10 to 14 days, decomposition loosens up the vegetation and makes planting easy again -- except if it rains in the meantime. Then, the vegetative matter stays wet and tough, and "even sharp openers can't slice through it," Fuller says.

In 2014, wet and cool weather threw timing off completely, and Fuller and Karr were only able to use the roller on a few acres. Spraying became the only way to kill the cover.

Does all this complexity deter the two from their cover-crop addiction?

Fuller says, "There are not more things to worry about with cover crops, just different things -- like can we get the sprayer there at the right time?"

The benefits of erosion control, soil building and weed suppression that come with cover crops have convinced the two to do whatever it takes to continue learning about -- and maybe inventing -- the cover-crop system.

As for the roller, "It's not going to be the final answer [to killing] cover crops," Karr says. "It's just another tool in the toolbox."

(BAS)

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