Looking at cover crops
Results of cover crops research at Iowa State Research Farms in Iowa was the subject on March 10, presented by Tom Kaspar, a cover crop management researcher with the National Laboratory for Agriculture and the Environment.
Federal incentive plans for growing cover crops was also the subject of a March 28 meeting in Woolstock.
When does one establish a cover crop when using overseeding methods?In soybeans, Kaspar suggested at the beginning of leaf yellow, in mid- to late-August using aerial seeding or a tractor broadcast spreader.
Suggested covers in soybeans are oats or rye. “Rye can reduce erosion of topsoil by half,” Kaspar said. “This cover crop can help to anchor the soil, preventing washout.”
When overseeding corn, Kaspar noted, seed should be spread just before black layer when the lower leaves of the corn plant are turning brown – usually in mid-September. Aerial seeding of rye or oats should take place before Sept. 15. Kaspar suggests that growers watch crops’ maturity levels, the soil moisture, rainfall and temperatures and adjust the timing of cover crop seeding accordingly.
His suggestions for establishing small grain cover crops with a grain drill or shallow tillage were to seed them following seed corn, silage corn, early maturing soybeans and early maturing grain corn. Cover crops used should be winter hardy small grains like rye, wheat and triticale.
At the Woolstock meeting, local grower Arliss Neilsen, said applied aerial seeding in a cornfield and drilled rye into a soybean field last fall – a total of 350 acres. He said this year, he plans to aerial seed legumes into standing corn. “It seems to offer the most protection,” he said.
He said that planting rye ties up nutrients from escaping the field while it otherwise lays bare to the elements from harvest to canopy. “This makes more nitrogen and phosphorus available to corn following beans,” Neilsen said. He said in his two years of using cover crops, “it seems aerial seeding works better.”
Sarah Carlson, research and policy director for Practical Farmers of Iowa, said thee are a host of small grains that producers can use for cover crops including winter barley, oats, triticale, vetch, wheat, tillage radish and rye. Rye, however, seems to be the cover crop of choice in this region and radish seems to be ineffectual in this region, she said.
Carlson said a factor that keeps some producers away is the timing for killing the cover crop prior to planting. most experts says if a herbicide is used, it should be two weeks prior to corn planting and three days before soybeans. Other methods for can tilling it up, or rolling to break the plants.
The extra expense of another pass over the field and spraying, said Rick Lee, of Clarion, also “holds some guys back.” Lee used cover crops over 320 acres for the first time this year under a three-year federal incentive program. He said he’s uncertain how the program will pay for him. “After the three years, I’ll see how it worked for me.”
But according to John Holmes, an ISU Extension crops specialist, no-till producers like Lee will do okay with the extra pass over the field. But, he added, even conventional producers will find benefits of cover crops for the preservation of soil.
“You have to remember that the field is bare from harvest to April, and even to June before you get a decent canopy,” Holmes said.
Having cover crops rooted will better hold the soil in place during fall and spring rains, he added, “and the nitrogen it holds will be released again and available to the cash crop.”
Planting dates for these cover crops are mid-September through mid-October.When these methods are used there is a lower seeding rate than overseeding, but a more reliable stand is established. Grain drills and shallow tillage methods may destroy some surface covers.
Research at the National Lab in Ames finds that the best applications of cover crops for Iowa are winter rye following corn silage, sweet corn, seed corn, or early-maturing grain corn before soybeans. Oats are a good choice when over-seeded into soybeans at leaf drop or before corn for grain.
The only risks to crop yields found were a decrease of four to six bushels per acre in corn yields following a rye cover crop.
Some of the challenges of using cover crops includes time, input costs and the risk to corn crops as mentioned above.
Bruce Voights, with the Mississippi River Basin Initiative, a federally-funded program to get producers to voluntarily implement conservation techniques in the Boone and Des Moines River watersheds, discussed incentives available to producers.
Voights said there are four practices that participating producers can implement and receive payments for in the MRBI program – nutrient management, strip-tillage, cover crops and installing bioreactors.
Producer Lee said he just made it into the program beating the deadline by hours. He applied 1.5 bushels of rye seed on each of his 320 acres. Looking over the seeding rate, he said he may reduce that amount to a bushel this fall.
Contact Robyn Kruger at email@example.com.
Contact Larry Kershner at (515) 573-2141, Ext. 453 or at firstname.lastname@example.org.
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