Longtime advocate of soil health practices studies cover crops, fertilizer and row spacing – Agweek

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GOODHUE, Minn. — Goodhue County farmer and Soil & Water Conservation District Board Supervisor Ed McNamara continues to fine-tune his use of cover crops for forage, fertilizer and soil health.
This season, McNamara will experiment with row width, spacing and different types of manure. He was part of a three-year University of Minnesota and Cannon River Watershed Partners research project that finished in 2021.
McNamara farms the Belle Creek Township land his grandfather bought in 1928, and he started farming with his father in 1978, milking registered Holsteins for 25 years. His farm lies within three watersheds that drain to the Mississippi River — Hay Creek, a trout stream — and the Zumbro and Cannon rivers. The water table is high, the soil is a silty clay loam, he said.
“That makes things interesting, but it also presents the opportunities for adopting tillage practices and cover crops to lessen the impact for the water below us,” McNamara said.
A Goodhue County Soil & Water Conservation District Board supervisor for the past 24 years, McNamara is also a certified crop adviser. McNamara enjoys helping other farmers who might be interested in cover crops, and recently discussed what’s worked for him, what hasn’t and how he’s adjusted.
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“We’ve got the agronomic side figured out. Now we’ve got to get the individual producers’ management styles to change,” McNamara said. “If you only use your field five months of the year, the other seven months of the year it could be growing one, maybe two crops. Isn’t that a more efficient use of the highest-priced asset that you have?”
McNamara has experimented on his own, with assistance from the USDA’s Natural Resources Conservation Service and as part of research projects.
He’s no-tilled soybeans into corn stubble every year since that first cost-saving experiment in 1997. The oats-and-peas cover crop he seeded as a prevent-plant measure in 2013 fed the cattle that November and expanded the slate of soil health practices he’s made permanent on his 350-acre corn-and-soybean farm.
“I really haven’t looked back,” McNamara said of no-till.
NRCS assistance allowed him to experiment with cover crops early on, through the Conservation Stewardship Program, and with nitrogen application rates through the Environmental Quality Incentives Program.
In a three-year research project that finished with the 2021 harvest, McNamara interseeded cover crops between 30- 60- and 90-inch corn rows. A University of Minnesota agronomist and a Cannon River Watershed Partners conservation program manager worked with him and three other farmers to determine how row width affected corn yield and cover crop biomass and if wider spacing could be profitable.
On his own in 2021, McNamara planted twin-row corn 7.5 inches apart in east-west rows. The spacing made it possible to harvest with a 30-inch corn head. Staggering plants within the double rows exposed the cover crop to more sunlight, he said. Rows planted north-south receive three to four hours of sunlight a day, said McNamara, while east-west rows are more shaded.
This spring, he’ll alternate 10-foot-wide strips of four, 30-inch twin rows of corn with 10-foot-wide strips of cover crops. After each cover crop harvest, he’ll apply a different type of manure — beef, turkey and hog — and then plant corn on that strip the following year. The aim: to maximize the cover crops’ feed value, determine how much phosphorus intensively managed cover crops will take up, and potentially eliminate the need for commercial fertilizer next year.
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McNamara was one of four farmers in Goodhue and Rice counties who participated in a three-year research project to determine if planting cover crops in corn could be profitable.
The Clean River Partners and University of Minnesota study examined how corn row spacing affects not only yield but also the growth and profitability of forage cover crops. A Minnesota Department of Agriculture sustainable agriculture project grant supported the study, which ended in 2021. Clean River Partners expects to publish the final results on its website later this spring.
“What we were really looking at was if we plant corn in wider rows, can we grow more cover crops, and if we grow more cover crops, then how does that impact the grain yield,” said Alan Kraus, conservation program manager at Northfield-based Clean River Partners.
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