Looking back 171 years to when his farm was first surveyed, Iowa farmer Steve Berger knows “we've lost half the organic matter in soils. Today’s fencerows are one indicator on our farm, as they test 5.8% and 6.6% organic matter versus 3.4% and 3.7% just a few inches away.
“Farmers are depleting organic matter pretty quickly. Our goal is to preserve or increase it,” Berger says. “We aim to have something growing year round, and that’s where our cover crop comes in.”
He first seeded cereal rye as a cover crop on a continual basis 12 years ago on his 2,100-acre southeastern Iowa crop and livestock operation. His father Dennis began no-tilling their ground in the late 1970s, so early adoption is a tradition there.
“Cereal rye is our chisel plow; it makes a tremendous 30-48-in.-deep root system for the corn roots to follow down,” Berger says. “If those roots grow just 1 ft. deeper, that’s 2 in. more available moisture. In some years that’s a big deal.
“When I tile, I see 16-in.-deep rye roots already in the fall, along with earthworm channels.” (In fact, cereal rye roots were 48 in. deep, in core samples on Berger’s farm taken March 27 by Tom Kaspar, plant physiologist, USDA-ARS National Laboratory for Agriculture and the Environment. “Granted, this spring was a very unusual year,” Kaspar adds.
Berger’s yields average 10-15 bu./acre over the county average with similar soils. “We have fields with APH insurance yields over 200 bu./acre corn and near 60 bu./acre for soybeans,” he says.
His biggest cover-crop challenge is getting everything done in the fall because harvesting beans in the last three weeks of September overlaps with drilling rye.
He drills rye right after harvest, and by spring has 6-10 in. of rye growth. “The drill helps speed up stalk decay and works them down, similar to light disking,” Berger says.
“That anchors the soil April through October.”
Cereal rye can be planted as late as early November in east-central Iowa (Wellman) where Berger lives and still provide some benefits, Kaspar says. “This is a key cover-crop benefit. Cover crop plants anchor the loose surface corn or soybean residues, making them much more effective at preventing erosion.”
At planting, the path cleared by row cleaners stays clean to help corn emerge, Berger says.
Berger buys the rye seed from a local grower in semi loads and stores it in bulk bins. “The cover crop seed cost is about the same as what a neighbor pays someone to chisel plow. It’s a good investment in soil quality for future generations.
“Cover crops like cereal rye and radishes need to be planted in late August to become established before our cold winters. We never want to see bare soil,” Berger says.
He applies swine manure from his confinement units and turkey litter based on 2.5- acre soil grid sample results. He tests his manure and litter to know exactly what he’s applying on his silt loam and silty clay loam soils. His swine finisher manure tested at 38-20-30 most recently; his nursery manure at 32-15-22, and turkey litter tested at 35-64-30. He still needs to supplement with commercial potash for his K needs.
“In general, swine manure nutrient analyses have been decreasing because of ration changes. This is why constant manure testing is so important. N and P levels are off 15-20% from 10 years ago,” Berger says.
He uses several methods to apply the swine manure, including both Dietrich sweeps and Yetter Avenger disk openers. “Our goal is to apply manure with the least disturbance to the soil and rye,” he says.
Sidedressing has improved his N efficiency ratio to 0.8-0.9 lbs. N/bu. corn.
“Our goal is to spray the rye sometime around April 1 with 32 oz. glyphosate/acre. It’s stressful getting everything done, since some years we get snow on April 1,” Berger says.
“We’re too far north to be in double-crop country.”
Not all rye cover crops are the same
Steve Berger, Wellman, Iowa, plants cereal rye cover crop, as opposed to annual ryegrass.
Dan Undersander, University of Wisconsin Extension and research forage agronomist, explains the difference: “There is no such thing as cereal ryegrass. Cereal rye is a small grain; ryegrass (Italian, annual or perennial) is a forage. ‘Rye’ is used by some as slang for ryegrass, but this would not be appropriate, because either can be a cover crop.”
“There are many different varieties of cereal rye but we don’t pay much attention to the variety, and a lot of the rye is bagged without a stated variety,” he says. “Winter cereal rye is very cold-tolerant and planted into Canada.”
Berger plants cereal rye, meaning it can overwinter and continue growing in the spring.
“Annual ryegrass is generally suited for climates from southern Iowa to the south and east and is a popular feedstuff in the southern U.S. and eastern Corn Belt,” Berger says.
“There are some reports that some newer varieties of annual ryegrass have a more ‘northern’ range, but this will have to confirmed through trials and experience,” says Tom Kaspar, USDA-ARS National Laboratory for Agriculture and the Environment.
Berger adds, “It is difficult to establish annual ryegrass here (east-central Iowa) because of the cold winters--it will often freeze off here and die.
“You may hear of farmers using annual ryegrass in Wisconsin, Michigan, northern Indiana and Ontario. This annual ryegrass is planted close to the lakes where there is a more moderate temperature zone,” Berger says.
Kaspar advises potential cover-crop growers start planning the spring before, or at least by Aug 1. “My advice is to start small, and by that I mean one acre or 10 acres or whatever a farmer can ‘afford’ to learn and experiment with.”
To see the dramatic root growth of another cover crop, oilseed radish, known for breaking up compaction with its strong roots, see http://bit.ly/RadishRootGrowth