Cover crops provide environmental benefits and extended fall grazing
Following the 2012 drought, Jeff Koch planted about 25 acres of cover crops as a way to grow some extra forage for his cow-calf herd while also protecting the soil.
"I had a field that was harvested early," said Koch, a Madison County Farm Bureau member. "My main two goals were erosion control and grazing."
What he didn’t know at the time was that cover crops would become a key part of the Iowa Nutrient Reduction Strategy and other efforts that aim to improve water quality in Iowa’s lakes and streams. Research shows cover crops reduce nitrogen and phosphorus losses by about 30 percent.
So when Anna MacDonald was looking for farmers to participate in a project to reduce sediment and phosphorus loading in the Badger Creek Lake Watershed, Koch’s previous experience with cover crops made him a natural fit.
"He’s kind of a pioneer," said MacDonald, a project coordinator for the Madison County Soil and Water Conservation District.
The Badger Creek project aims to improve the lake’s water quality by working with landowners, residents and farm tenants. Farmers planted nearly 600 acres of cover crops as part of watershed improvement efforts this year, she said.
"If you have a sediment and phosphorus problem, it’s really one issue — and that’s erosion," MacDonald said at an Iowa Learning Farms field day in Van Meter.
Over the past four years, Koch said he’s experimented with several different cover crop seed mixes, timing and application methods. He’s seen consistent erosion control, but said the amount of forage growth for fall grazing can vary greatly depending on the weather. The best results have typically come by aerially seeding into standing crops in late August, he said.
MacDonald emphasizes patience among farmers trying cover crops or other conservation practices for the first time, noting that environmental benefits don’t happen overnight.
"The benefits accumulate over time. You might not see it in one year," she said. "We’re in year three (of the Badger Creek project), and we’re still learning and figuring it out. I don’t think any of us think we have all the answers. The important thing is to continue to make progress. It’s probably going to take 20 years."
It can take five to 10 years before soil tests show a definitive increase in organic matter, according to Sarah Carlson, cover crops research coordinator for the Practical Farmers of Iowa.
Research has shown farmers can gain a yield benefit of about 4 bushels per acre in soybeans planted after cover crops, she said. Corn yields haven’t yet shown a consistent benefit, but there isn’t a yield drag either, as long as cover crops are managed properly, Carlson said.
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