Dan Forgey is a master of mixology. His signature cocktails are blends of grasses, legumes and brassicas. He is agronomy manager for Cronin Farms, an 8,500-acre crop and cow-calf operation in central South Dakota. He grows eight cash crops – including corn, soybeans and wheat – and juggles an equal number of cover crops, which include field peas, oats, turnips, radishes, canola and flax.
Forgey has grown cover crops since 2006 on the sprawling no-till farm near Gettysburg, SD. His cocktails manufacture, catch and store nutrients for the corn crop, stop erosion, smother weeds, preserve soil moisture and supplement grazing.
Cover crops are nothing new. Only a couple of generations ago, it was routine to seed sweet clover with small grains for nitrogen (N) fixation, livestock feed and postharvest weed competition, says Dwayne Beck, director of South Dakota State University’s Dakota Lakes Research Farm at Pierre.
Beck has preached cover crops for 20 years. The practice dropped off with the rise of cheap commercial fertilizers and tillage. Now, with higher fertilizer prices and more no-till production, growers like Forgey are rediscovering the advantages of cover crops, Beck says – especially cover-crop mixes, which allow you to achieve “several goals simultaneously.”
Cover crops offera wide range of environmental and agronomic benefits, says Paul Jasa, University of Nebraska Extension engineer. They can prevent wind and water erosion on land that would otherwise be bare, reduce runoff and N leaching, build soil structure, break up compaction, fix N, recycle nutrients, feed beneficial soil organisms and supply extra forage.
Cover crops can preserve moisture in dry areas, or use up excess moisture in wet areas, Jasa says. You can also manage residue with proper cover-crop selection: “You can either get rid of excess residue in a hurry, or build up residue.”
In Nebraska, cover crops are becoming popular in livestock areas, where growers are planting triticale, cereal rye and wheat right after chopping corn silage “to give bare soil cover and rest pastures,” Jasa says.
Seed-corn growers, who harvest early, are planting turnips and radishes into standing stalks to provide grazing and speed up residue breakdown. And with wheat production on the rise, more growers are drilling cover-crop mixtures into wheat stubble in late summer to build soil organic matter and suppress weeds, Jasa says.
Dan Forgey’s primary aimin using cover crops“is to help build soil health.” He converted Cronin Farms to no-till 19 years ago. Since then, average organic matter levels have risen from 2.5% to about 4%. His strategy is to “build organic matter and then let our organic matter supply our nitrogen” through mineralization. Cover crops, he says, are “the next step in no-till.”
Forgey plants about 700 acres of cover crops each season, seeding into winter wheat stubble with a no-till drill in mid-August. In 2010 he planted a mixture of canola, field peas, oats, radishes and flax, and injected 25 lbs./acre of N as urea.
Each plant contributes something the soil needs, Forgey says.
“Canola has a good taproot, and it’s a bushy plant with lots of carbon and biomass. Field peas fix N. Radish has a deep taproot that breaks up compaction and improves water infiltration,” he says.
Flax and oats have large, fibrous root systems that improve soil structure and feed soil microorganisms. “Flax stands all winter,” trapping snow and stopping erosion, and oats do a great job of scavenging N and recycling phosphorus (P),” he says.
Cover-crop mixes like Forgey’s usually perform better than single crops, Beck says. “Mixtures add more diversity, grow at different times, better compete with weeds, optimize nutrient cycling” and make more efficient use of moisture.
Forgey arrived at his cover-crop formula through trial and error. Recently, he cut the proportion of brassica crops in the mix because he found that they depleted the residue too quickly, hurting yields in dry years. “Now I use a lot more grasses,” which create a more desirable carbon-to-nitrogen ratio.
Central South Dakota usually gets about 18 in. of rain a year. In dry years, Forgey cuts back a bit on the seeding rates. “But I’m not concerned about the amount of moisture lost to the cover crop,” he says. “Our fields with cover crops have just as much moisture as fields without cover crops.”
In fact, Beck says, “Water used by a cover crop during the non-crop period can often be regained before and during the growing season because of better infiltration and reduced runoff.”
Hard frost kills Forgey’s cover-crop mixes, so overwintering hasn’t been an issue. “In a mild winter, some plants may survive, but it doesn’t really matter. We plant corn into the cover crop and take out any survivors with our regular herbicide application,” he says.
Cover crops are an added expense, Jasa points out, and the benefits take a few years to accrue, especially if you don’t graze livestock. “That’s one reason most people aren’t doing this,” he says.
A three-year grant from USDA Sustainable Agriculture Research and Education (SARE) helped Forgey get started. To lower his costs, he raises some of his own cover-crop seeds, including radishes and field peas. He trades lentils for his neighbors’ oats and flax seed. That holds down his cash outlay to about $8/acre – a third of what he would have to spend to buy the cover-crop seed mixes. Cronin Farms also grazes about half the cover-crop acreage in the fall, earning an immediate economic return.
Yield responses to cover crops have been mixed so far, Forgey says. In 2008, corn yields were higher on cover-cropped ground than on non-cover-cropped ground. In the following crop, sunflowers, there was no yield difference. And in 2010 – a dry year – spring-wheat yields were lower on the cover-cropped ground.
But Cronin Farms’ overall yield trend is increasing, says Forgey, a frequent speaker at no-till and cover-crop events. He considers both strategies a long-term investment in soil quality. “It’s farming for the future.”
Forgey has been a part of Cronin Farms for more than four decades, and he harbors “a deep love and respect for this land. I’m a firm believer that if you take care of the land, the land will take care of you. That’s the philosophy on this farm.”
There’s a lot of cover-crop innovation going on around the Corn Belt. Growers are:
• Aerial seeding cereal rye or a mixture of rye, turnip, radish and legumes into standing soybeans, just before leaf drop. As the soybean leaves drop, they provide mulch for the cover crop. By the time soybeans are ready for combining, the cover crop is up.
• Planting tillage radish or Austrian winter peas between harvested corn rows or in wheat stubble to clear residue from a strip for the next crop – without using tillage.
• Incorporating cowpeas or winter peas into continuous no-till corn-soybean-wheat rotations. The legumes can produce enough nitrogen for the following corn crop, according to research from Ohio State University.
• Slurry seeding manure and a fall cover crop in a single operation. The cover crop takes up the nutrients and stores them for use by the following cash crop.
• Seeding cover crops with fall P and K applications, or retrofitting cultivators or combines to till or harvest and seed a cover crop in one pass.
• Planting oats in early spring to dry out excessively wet soil, letting the cover crop grow for a few weeks, then killing it and planting soybeans.
• Drilling soybeans into standing rye, then burning down the rye five to 10 days later, or letting the rye go to the late dough stage, then mowing it and drilling soybeans into the living mulch.
Sources: Sarah Carlson, Practical Farmers of Iowa; Paul Jasa, University of Nebraska Extension; Dwayne Beck, South Dakota State University Extension; Rafiq Islam, Ohio State University
Dan Forgey, agronomy manager for Cronin Farms in Gettysburg, SD, manages a dozen different rotations. Cronin Farms produces corn, soybeans, winter wheat, spring wheat, sunflowers, dry peas, lentils, millet and alfalfa on 8,500 acres of dryland and irrigated cropland.
Here is a typical cash crop rotation on Cronin Farms, which includes a cover-crop cocktail every fifth year:
Year 1 Spring wheat
Year 2 Winter wheat
Fall-seeded cover-crop mixture, such as canola, field peas, oats, radish, and flax
Year 3 Corn or dry peas
Year 4 Sunflower or winter wheat
Given the benefits of cover crops for the environment and the soil, why aren’t they more widely used?
A recent survey from the Conservation Technology Information Center and Corn & Soybean Digest found that only about 20% of growers plant cover crops. In Iowa, farmers planted fewer than 50,000 acres of cover crops in 2010 – out of more than 23 million acres of corn and soybeans, says Sarah Carlson of Practical Farmers of Iowa, a farmer-to-farmer education and on-farm research group.
One of the biggest challenges for northern farmers is the short window to plant and establish cover crops in the fall, says Dwayne Beck, a South Dakota State University agronomist.
Cost is another barrier, Carlson says. Seeding expense runs about $25/acre, although there are ways to lower your costs by growing your own seed or concocting cover-crop cocktails from whatever you have left over in the seed bins, says Paul Jasa of the University of Nebraska.
It takes some time to reap the benefits of cover crops, too, Jasa adds. “It’s probably not going to pay in the short term.” For the first few years, “you are building up the soil. By years four, five or six, you are finally picking up yield increases.”
Yet economics may not be the main hurdle, Carlson says.
In 2008, the EQIP program offered Iowa growers $31.50/acre to plant a cover crop, “but there were few takers.” In 2009, the Mississippi River Basin Initiative offered growers in selected counties $60-108/acre to plant a cover crop. At that price, “I thought I’d see more cover crop acres this year,” Carlson says. “So I don’t think money is the main issue.”
As she sees it, the biggest barrier to adoption is a lack of know-how and experience. “There’s a ton of interest in cover crops,” she says, “but farmers haven’t had anywhere to go for information or help on how to do it.” A mature network of industry services and expertise doesn’t yet exist for cover crops, as it does for traditional crops, she adds.
Before growers will have the confidence to try cover crops, they will need detailed knowledge on cropping alternatives, best agronomic practices and economic risks, she says. “We need to get at the numbers, and we need long-term research. There hasn’t been much of that yet.”
Cover-Crop Resources
Information on cover-crop cost share and grant programs, and more: www.sare.org
Managing Cover Crops Profitably:
http://sare.org/publications/covercrops.htm
Midwest Cover Crops Council: www.mccc.msu.edu
Cover-crop selection tool: www.greencoverseed.com
Practical Farmers of Iowa Cover Crops Hotline: 515-232-5661 or www.practicalfarmers.org
January 2011