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Farmer sees benefits in letting cover crops grow tall

Doug Adams heard the coffee-shop talk last spring when a rye cover crop in one of his fields grew seemingly out of control, reaching shoulder-high in a field due to be planted to soybeans.

"You heard people say Doug’s got quite a mess. People raised some eyebrows," said Adams, a Humboldt County Farm Bureau member.

Letting the rye grow that tall wasn’t his original plan, but a wet spring forced him to make adjustments. Instead of terminating the rye under less than ideal conditions, Adams decided to let it grow and "plant green" by seeding soybeans into a living cover crop on June 2.

It was something he hadn’t tried before but he had read success stories about farmers in other states, such as Dave Brandt in Ohio, who have done the same thing.

"He was planting into rye up to the hood of his tractor. I’d never seen it get over knee-high," Adams said. "I was nervous, but watching it close and knowing what other farmers have done with rye this tall gave me the confidence to follow through."

It worked so well last year that Adams planted "green" again this year in three different soybean fields totaling about 120 acres.

Last year’s experience

It’s still an unusual sight to see a thick stand of grass covering the planter wheels as Adams puts his soybean crop into the ground, but last year’s experience convinced him of the benefits.

"Last year was a rainy spring. I let the rye grow for quite a while, drawing the excess moisture out of the ground, and in the end we ended up with some excellent weed control, so that’s what I’m trying to duplicate this year," said Adams, who also works as a soil conservation technician for the Natural Resources Conservation Service in Humboldt.

"In addition to the weed control, I also use the cover crops to use up any excess nutrients that were left over from last year’s crop, hopefully recycling those for this year’s crop or for future use, building more organic matter as well," he said.

Last summer, the cover crop residue provided a layer of mulch that served as a weed barrier between soybean rows, Adams explained. After spraying and planting, he used a soybean roller to flatten the rye and allow more light to reach emerging soybean plants.

"When we rolled that rye down, it laid like a 3-inch mat on the ground," he said. "I had excellent weed control from day one. Very few weeds were growing through it."

Other than at the edges of his field where the cover crop was thinner, he saw nearly no ragweed. Weed control was so good, in fact, that Adams withheld a pre-emergence herbicide application on some of his acres this year to get a better look at how much the cover crop is helping keep weeds at bay.

Weed control

"Last year I treated it like all the rest of my fields. I used a higher rate of glyphosate to kill that tall rye, plus 2,4-D and Enlite," he explained. This year, he left Enlite out of the mix on part of a couple of the fields.

"I can see if there’s no difference in weed control, if the rye was doing all the work," he said. "If it can reduce herbicide costs, that helps pay for it."

Perhaps most importantly, Adams said there was virtually no yield difference last fall between his regular no-till soybeans, which averaged 58.7 bushels per acre, and those planted into the cover crop, which averaged 58.6 bushels.

"The fields aren’t right next to each other, but that’s a pretty good comparison," he said.

Still, there are challenges and a learning curve just as with any new farming practice, he said. He planted May 23 this year, 10 days earlier than a year ago due to a forecast showing chances of rain for a week or longer.

"With rain in the forecast, I didn’t want to wait to plant beans, so I pulled the trigger earlier," he said.

Working in green rye

He planted a day or two after terminating the crop. Waiting to plant until the rye dies and starts to fall over would increase the chances of it getting tangled in the planter, he said.

Setting up the planter going into rye is much the same as for other no-till planters, noted Adams, who uses strip-tillage on his corn acres and no-tills soybeans. Shark-tooth row cleaners help smooth a path for seed to be planted at proper depth and accuracy.

"The rye was still pretty green (at planting). It flows pretty good through the planter," he said. "I like planting when it’s still standing."

However, the rye didn’t lay down as flat after rolling this year compared to a year ago, possibly because it was shorter, so Adams plans to roll it again after soybeans get a little more growth. The roller is the same as those commonly used to roll conventionally planted soybean fields to smooth out the seed bed, pushing rocks and corn stalk residue into the earth to make harvest easier.

"There’s specialty rollers for cover crops, but for now I’m using what’s available in the area," he said.



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