Benefits of cover crops touted in Yahara watershed

Jan Shepel

De Forest - At its annual watershed conference, the Yahara Pride Farms organization showcased what its farmer members are doing to protect the Yahara River watershed, what others are doing in the state and outlined research results driven by those farmer practices.
            Bob Uphoff, a hog producer who farms in southern Dane County and has been involved with the group since it began, said the group was formed to “do the right thing” environmentally. Besides showcasing best management practices, the annual watershed conference is held to recognize those farmers who are doing all they can to protect the environment, preserve their soils and protect groundwater and surface water.
            “We want to say to those farmers ‘congratulations and job well done’,” he added. “Five years ago we had no idea that we’d be doing anything close to what we’re doing now.”
            He credited the strong backing of a number of sponsors who help pay for cost-sharing for farm practices like cover crop establishment as well as public outreach like the annual conference and field days held each summer.
“We couldn’t do it alone. We thank those sponsors for all their help.” Those sponsors include Clean Lakes Alliance, Badgerland Financial, Dairy Business Association, Dairy Business Milk Marketing Cooperative, McKnight Foundation, Middleton Community Bank, National Fish and Wildlife Foundation, United Cooperative, Wisconsin Department of Agriculture, Trade and Consumer Protection, Wisconsin Milk Marketing Board and Yahara WINs.
One of the key practices the farm group promotes on area farms – the watershed runs through Dane County and touches parts of Columbia County to the north and Rock County to the south – is establishment of cover crops on cultivated fields. The practice and research into its management, is spearheaded by Dane County UW-Extension’s Crops and Soils educator Heidi Johnson.
At the watershed conference Johnson moderated a panel that included a soils expert, an area farmer who has practiced cover cropping on his land and an aerial applicator who works with farmers to plant cover crops from the air.
Jamie Patton, a UW-Extension soils educator in Shawano County, told the farmers who attended the conference that cover crops and determining if they make “cents” involves “fuzzy math.”
“It’s a biological system within a biological system and it is often unpredictable,” she said.
Patton noted that in general cover crops can be used to improve soil structure, nutrient cycling, soil organic matter and water retention along with microbial activity. A one-percent increase in soil organic matter can be worth 1,000 pounds of nitrogen and 100 pounds each of phosphorus, potassium and sulfur, valued at $400, $40, $30 and $60 respectively. That’s a total $530 in nutrients for each 1 percent increase in organic matter, she said.
Since coming to Shawano County from her previous position working on soil health in Missouri and an upbringing in Iowa, Patton has been doing multi-year cover cropping trials on depleted soils in her area. Cover crops have shown an “impressive” ability to bring organic matter back to the soils in her on-farm trials.
On the contrary, seven years of cover crop trials, done by Practical Farmers of Iowa, didn’t show an increase in soil organic matter at all, she said. That highlights the unpredictable nature of a biological system. (Her theory is that those deep, rich Iowa soils weren’t nearly as degraded as those she is working with near Manawa.)

Soil compaction benefits

Another benefit of cover cropping, Patton noted, is the alleviation of soil compaction and improved soil structure. Compaction can cause 25-50 percent yield losses. “At $3 corn that translates to $112.50 per acre,” she said. “Cover crops open up root channels and keep them open; it doesn’t allow soil pores to close. Those roots of the cover crop maintain the porosity of the soil.”
Farmers who plant cover crops tell her that planting into those cover crops is like “planting into butter,” she said. “This means less tillage costs and an increase in internal drainage in that soil.”
Nutrient cycling, one of the touted benefits of cover cropping, is a complicated process mediated by environmental conditions and microbial activity and its value can seldom be determined by using simple accounting methods. Though it’s difficult to put a dollar value on it, Patton said that nutrient cycling is extremely important to maintaining crop production.
One percent of soil organic matter can hold 27,000 gallons of water, she noted and it takes 3,000 gallons of water to grow a bushel of corn. A soil profile with 5 percent organic matter means that it can hold 7-10 days of the water a corn crop will need. “On those hot July days when it doesn’t rain, that organic matter means that the corn plants will have the ability to survive.”
As such, cover crops help soils with resiliency, she said. When severe drought hit Wisconsin in 2012 farmers saw the benefit of cover cropping. In research she outlined, those fields that had a history of cover cropping yielded 144 bushels of corn per acre despite the drought. Those without cover crops yielded 103 bushels per acre.
“The only downside (to cover crops) is the added cost,” she said.

Farmer perspective

Nick Viney, a sixth-generation farmer from Evansville, said his family began working their land in 1849 and now has expanded that operation to 1,600 acres in Dane and Rock counties. Their farming practices include strip tillage for corn and no-till for soybeans. They also grow small grains.
            He has been utilizing cover crops on well over 1,100 acres since 2011 to limit erosion, sequester nitrogen and promote healthier, more resilient soils.
            “But the cost has got to be reasonable, it can’t be complicated and it can’t hurt my grain crop yields,” he said. “And the cost-sharing is essential to cover the short-term economics.”
            Viney has experimented with a variety of cover crops. Species like crimson, berseem and red clover, radishes and turnips, rapeseed and Austrian winter peas work best after small grains, he said. He has also used annual rye grass, spring barley, oats and cereal rye on fields planted later in the season.
            His cover crops have been planted with aerial seeding, broadcast seeding, drilling and precision seeding using a planter.
            On his fields, broadcasting seed has been coupled with a fall fertilizer application since he was already making that pass in the field anyway. But he has noticed that that seed sometimes doesn’t germinate. If he is planting cover crops following a small grain crop, Viney often plants in 15-inch rows using 2 pounds of radish seed with 13 pounds of Austrian winter pea seed per acre.
            That mix also provides a nitrogen gain in the soil as the winter peas are a nitrogen-fixing plant. Viney figures that the practice runs him about $13.50 per acre for the seed and $13.50 per acre in planting costs.
            His practices include no-tilling soybeans into rye, which he said helps control annual weeds.
            Viney figures that a half-ton of reduction in soil erosion is valued at from $3-$6 per acre and an increase in soil organic matter at one-tenth of a percent per year is worth $7 per acre. (He admits that such an increase in soil organic matter could be optimistic in actual practice.)
            Using Ohio State research, a 1 percent increase in soil organic matter equates to a 12 percent increase in crop production, he noted.
            The use of cereal rye as a cover crop can reduce soybean cyst nematodes in the soil by 50 percent and reducing that important pest can mean an extra 4 bushels of beans per acre or $38 per acre, he said.
            Using cover crops can reduce nitrate losses from the soil by 30-50 percent and phosphorus losses may be reduced by 10-30 percent.

Aerial seeding

A panel including (from left to right) aerial applicator Damon Reabe from Waupun, farmer Nick Viney, operator of Badgerland Grain Farms in Evansville and UW-Extension soils educator Jamie Patton from Shawano County talked about the pros and cons of cover crops during last week’s Yahara Pride Farms watershed conference.

Damon Reabe with Dairyland Aviation, operates eight aircraft serving agriculture in Wisconsin. He outlined for Yahara Pride farmers the practice of planting cover crops into standing silage corn, something he’s been doing on a number of farms for the past five seasons.
            Showing photos of spring barley that was planted into standing corn on Double S Dairy in Markesan, Reabe said he uses 2 bushels of spring barley flown onto the field about two weeks before the scheduled harvest of the silage.
            “If it germinates and gets growing before the harvest it will gain a lot of heat units,” he said.
            Oats have also been used in cornfields that were scheduled to be harvested as silage. On some of those fields farmers are even able to “splash” liquid manure applications of as much as 12,000 gallons per acre in the fall without killing the cover crop. “Those oats are extremely resilient. If the plants are six inches tall, splashing manure on top will not kill it.”
            Pen pack manure spread on top of a cover crop, however, will definitely kill the cover crop, he added.
            The cost of aerial application is $10 per acre plus the cost of the seed, he said.