A multi-state partnership launched three years ago by the National Corn Growers Association is striving to have 100 farmer members who would commit to five years of on-farm projects designed to compare how differing management practices affect soil health.
Titled Soil Health Partnership, the network has enrolled 65 members – the great majority of them in Iowa, Illinois, and Indiana. At the moment, there are three in Wisconsin.
One of the Wisconsin farms is operated by father and son Dennis and Dan Roehrborn in central Sheboygan County. They hosted a recent field day to show what they are doing as part of the demonstration project, which involves comparisons of results on strips within the 20 to 80 acre fields which are required for the Soil Health Partnership.
For the 7th year, the Roehrborns are growing cover crops, which are reputed to be one way to improve soil health, on a portion of the 740 acres that they own and additional 260 that they rent. Most of their cover crops have been grown on land from which winter wheat was harvested.
To reap the top benefit from cover crops, Dan Roehrborn told the field day attendees that the planting should occur by August 15. Waiting until September 15, which could be on the heels of harvesting corn silage in most years, would be too late, he stated.
After several trials with various cover crop species and plots in cooperation with the Sheboygan County Extension Service and the Nature Conservancy, the Roehrborns have settled on a combination of barley, crimson or Berseem clover, and tillage radish – 105 acres directly seeded after winter wheat and 60 acres interseeded into corn this year. Highly erodible land is their top choice for growing cover crops.
Refining the strategy
One of the strategies with growing cover crops is determining the proper seeding rate, the Roehrborns quickly learned. One lesson is that 10 pounds of tillage radish seed per acre was far too much and that oats was not as good a late season choice as barley.
To address that question, the Roehrborns spent a couple of weeks last February building a seeder designed to accommodate planting between soybean and corn rows. A special feature of that unit is a control apparatus that controls the seeding rates.
To test the unit, the Roehrborns set aside a couple of acres - visited by the field day attendees – this year as an experiment on what would be the appropriate rates. Because the Farm Service Agency requires that all planted acres be reported, Dennis Roehrborn said they were described as a “wildlife food plot.”
Settling on seeding rates
The Roehrborns have settled on per acre seeding rates of 30 pounds of barley and 3 pounds each of one of the clovers and tillage radish. Dan Roehrborn noted that the barley and radish continue to grow until the temperature drops to 18 degrees.
Gaining access to a cement mixer was helpful in mixing the seed batch, the Roehrborns reported. They mixed it in batches sufficient to plant 20 acres.
Field day attendees also discussed the possibility of mixing cover crop seeds with liquid manure for a single application. This has been done in a few cases but Dan Roehrborn was wary of doing that, noting that it depends on how wet or dry the soil is.
In the spring of 2016, the corn planted in the dedicated Soil Health Partnership field got off to a slower start – as shown in images collected by a drone – in the strips where barley was the cover crop in the autumn of 2015, the Roehrborns observed. They surmised that this might have been due to a difference in soil moisture or in available nutrients.
On that point, Sheboygan County Extension Service crops and soils agent Mike Ballweg reviewed data from another farm in the county, which compared grain corn yields where there was no previous year cover crop, where barley was grown, and where a clover (Berseem or crimson) was grown.
Corn yields were 20 to 35 bushels less per acre following the barley and about 15 bushels less where there was no cover crop compared to where the clovers had been grown, Ballweg noted. He and other observers listed such possibilities as use of residual nitrogen by the barley or non-availability of the nitrogen following the breakdown of the barley foliage.
When winter cereal rye was grown as the cover crop, a challenge arose the following spring due to the heavy and slow drying soils in the area. An excess of spring rain delayed the termination of the rye and the planting of the following corn crop.
According to Soil Health Partnership director Nick Goeser, the goal of the project is to supply research data on how the combination of cover crop, tillage practices, and nutrient management affect the economics of crop production, improvement of soil health, and protection of environmental resources. He acknowledged that weather, equipment, and labor availability will all play a role.
Participating farmers are required to enroll 20 to 80 acre fields, which are divided into eight strips with differing treatments, including no cover crop growth, Goeser explained.
Additional requirements are the taking of soil samples in the spring for soil health assessments (an embellishment on existing soil sample testing), collecting crop yield data (the Roehrborns grow only corn after a cover crop), providing economic data on input costs and crop income, and holding at least one field day during each of the five years of commitment to the project.
“Soil health is the next frontier in the progression of agriculture,” Goeser believes. “More farmers are realizing that every day.” He says the Soil Health Partnership encourages innovation and industriousness for achieving the stated goals – one of which could be preventing the United States from suffering the same fate as other civilizations which collapsed because they failed to protect the productivity of the soil which was the basis of their society.
While the project is being spearheaded by the National Corn Growers Association, it also has the support of the United Soybean Board, the Monsanto Co., the Environmental Defense Fund, the Walton Foundation, the Natural Resources Conservation Service, and the Nature Conservancy, Goeser pointed out.
In the local area, a particular concern is the protecting the quality of water in the river basins which drain into Lake Michigan, according to John Nelson of the Nature Conservancy. He would like to see more interest in growing cover crops on fields from which corn is harvested for silage.
To accommodate that, Nelson suggested such seeding possibilities as aerial application or field travel with a Hi-Boy unit. He also advocates minimal soil disturbance techniques for the application of liquid manure with the use of equipment that is available from several suppliers.