These enriching cover crops differ from one region to another. And in areas where high winds can sandblast young seedlings and excessive water can wash them away, they can speed up stand establishment.
“It’s a lifesaver,” says Lonnie Gibson, Arbyrd, MO, grower. “You don’t have to worry about wind blowing out the crop in the spring.”
Dale Mutch, a Michigan State University Extension specialist and project coordinator for the Midwest Cover Crop Council (MCCC), says cover crops preserve and improve soil quality, which can decline under a repeated corn-soybean crop rotation.
And more are needed.
“Our overall goal is to get more cover crops – annual and perennial – in the landscape,” says Mutch. “Though they aren’t harvested as commodities, adding a cover crop system adds green plant material back into the soil, which can make the land more profitable.”
Erosion can be a major deterrent to a continuous corn-soybean rotation. Gibson grows both, along with cotton in southeast Missouri. He has over 15 years’ experience in using a cover crop with corn grown in primarily sandy loam soil.
Gibson plants the wheat cover crop just after corn or soybean harvest at a rate of 20-30 lbs. of seed/acre. He uses a Gandy air seeder attached to a One Pass TerraTill plow he runs after harvest.
The wheat sees a good stand by early November; its roots and surface growth protect against harsh elements all winter and up to and after planting.
Knowing when to terminate the cover crop is essential. For corn, Gibson applies herbicide when it’s 7-8 in. tall. “You don’t want the wheat to compete with the corn,” he says. “Once it’s killed, it takes 10-20 days for the cover crop to lie down.”
For soybeans, he terminates wheat when it first heads out. “You can get too much foreign matter on the beans if you go further than that,” says Gibson.
Last fall’s damp, cool weather prevented much wheat planting by Gibson. To compensate, he came back with spring oats early this year. “On the sandy soil, we went with 100% oats,” he says, adding that different blends of oats and wheat were planted in more firm soil.
Cover crops can help prevent severe water runoff damage on serious sloping fields. Research over the years from Purdue University shows that over 40% of Indiana’s cropland acres have sufficient slope to be seriously damaged by water erosion if not adequately protected.
Eileen Kladivko, Purdue agronomist, says that one of the primary uses for cover crops is to cover the soil to protect against water erosion. This can be especially important after low-residue crops like soybeans or corn silage.
“If cover crops are incorporated into the soil in spring, both water runoff and soil erosion are significantly less than with no cover crop,” she says. “Even larger reductions in soil erosion occur if cover crops are killed and left on the surface for subsequent no-till planting of corn or soybeans.”
Purdue researchers say coarse-textured soils and mucks can see improved production by using a cover crop and no-till planting to prevent wind erosion.
Gibson says cover crops can often save young plants following a quick rainstorm when soil can crust over. Strong winds whip around the crusted sand, threating to slice plants off.
“With a cover crop, you can rest easier when those March or May winds come,” he says.
Hairy vetch has been a popular cover crop for some areas. Purdue scientists note that some areas should see better response to extra nitrogen (N) fixation when corn is planted in hairy vetch.
Kentucky experiments as far back as the 1980s show that winter cover used with no-till planting markedly increases corn yield. For instance, three-year average continuous-corn yields were 8 bu./acre greater when planted into a winter cover of rye and 25 bu./acre greater when planted into hairy vetch than yields from plots without winter cover.
The higher yield in the hairy vetch cover plots was due primarily to the extra N the legume provides. (All plots in the experiments received 88 lbs. of N.)
Kladivko points out that production areas with shorter growing seasons in central and northern regions would likely not permit that amount of growth and N fixation.
She adds that the benefits of cover crops go beyond preventing erosion. “Cover crops trap the soil nitrate and keep it out of the tile drain tubes,” she says. “They also help build soil tilth and soil quality.”
Cover Crop Decision tool
MCCC aims to increase cover crop systems throughout the Midwest by combining the resources of land-grant universities in Michigan, Illinois, Indiana, Ohio, Iowa, Minnesota and Wisconsin, as well as universities in Ontario, Canada.
MCCC is working to create a cover crop matrix for the Upper Midwest, to develop research projects aimed at demonstrating how cover crops can improve water quality and to work with plant breeders to create new and improved cover-crop seeds.
More farmers are needed in the mix, says Mutch, who believes that involving farmers and representatives from non-governmental organizations, academia, agribusiness and federal and state governments on the committees will enhance the adoption of practices that they uncover.
Gibson says the benefits of cover crops should have more growers considering them.
For more on cover crops and the MCCC, go to http://www.mccc.msu.edu.