Last autumn, Martin Larsen and some of his neighbors pitched in together to grow oats on about 125 acres of their land.
The cover crop was so successful, he plans to double his portion from 50 acres to 100.
Much of that success is easy to measure — income from the crop, money saved from having to apply less herbicide on the field in the spring, and lysimeters on his land measured less nitrate runoff from the soil.
Other benefits, such as building soil health and carbon absorption, are harder to measure but are equally important to efforts to clean water and mitigate climate change, he said.
Larsen, feedlot technician with Olmsted County Soil and Water Conservation District, talked about that success and gave a tour of other cover-crop strategies being tested at the Olmsted County SWCD’s soil health farm Wednesday.
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Laura Bishop, commissioner of the Minnesota Pollution Control Agency and chairwoman of the Environmental Quality Board; Thom Petersen, state agriculture commissioner; and representatives from the Minnesota Bureau of Water, Soil Resources attended the event.
Nitrate contamination of groundwater, wells and waterways is especially a concern in Southeast Minnesota, Bishop said.
The unique karst geography in the region has features such as caves, hollows and rolling hills that are formed mostly of limestone, Bishop said. This kind of topography makes water more difficult to protect from nitrate contaminants used in fertilizers.
Nitrate levels in Southeast Minnesota are frequently found above the MPCA’s 10 parts-per-million standard. High levels can be harmful to infants and is linked to higher cancer rates .
Bishop’s stop in Olmsted County on Wednesday was part of her tour across the state for Minnesota Climate Week.
She said local efforts to promote and learn about cover crops can help address water contamination and help mitigate carbon emissions contributing to climate change.
“Agriculture often gets beat up as a contributor to this,” Bishop said. “We see them as part of the solution.”
The approximately 40 acres of cropland at the county soil health farm gives Larsen and other county officials a chance to demonstrate the benefits of different cover crops and techniques side by side.
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“We want (farmers) to learn from our mistakes before they take it on to larger fields,” said Angela White, Olmsted County conservation technician.
Larsen pointed to a plot of land with no cover crops compared to land with winter rye between the corn rows. He said the plot with rye cover crop had suppressed weeds as effectively as most herbicide applications.
“Compare the weed suppression,” he said. “It’s black and white, the difference.”
Larsen said the biggest obstacle to convincing farmers to plant cover crops is habit.
“We’re taught to plow and till and have our fields black and clean,” he said.
He said he hopes that changes in time. Demonstrating success on test acres in the county is one thing, but demonstrating methods on some of his own 700 acres sets a real-world example.
“It’s putting your money where your mouth is,” he said.
