

Lake Byllesby southeast of the Twin Cities is popular for boating, fishing and swimming. However, the lake suffers from excess nutrient levels that fuel algal blooms. Farm runoff is one source of those nutrient levels.

David Legvold farms land near Northfield that drains to small creeks that feed the Cannon River and ultimately Lake Byllesby. He is studying fertilizer rates on his farm to identify the optimal amounts that yield profits for him without hurting waters downstream.

“Many of my colleagues like to talk about yield. I’m thinking that’s less important. It’s more about not leaving dollars in the field, not about leaving bushels in the field,” Legvold says.

By tapping into the federal Conservation Stewardship Program, Legvold continues to incorporate several conservation practices into his farm operation, including managed drainage to prevent nutrients leaching from his fields and high residue management to keep soil in place.

The program also helped pay for on-farm research of nitrogen fertilizer applied to corn crops. Legvold worked with Rachel Weime, a biology student at St. Olaf College, to study nitrogen applications right on his farm.

Legvold uses an online calculator from Iowa State University Extension to figure out nitrogen rates for his corn crops. The research entailed applying nitrogen at the recommended rates along with higher and lower amounts. The research verified that the recommended rates were optimal for both cost and yield. While higher nitrogen rates did boost yields, the increased revenue was not enough to cover the extra fertilizer costs.

While profitability is important to Legvold, it’s not the only priority.

“It’s not so much about the pocketbook but how I feel about myself and my land,” Legvold says.

The MPCA is working with the Cannon River Watershed Partnership on strategies to reduce nutrient levels and the resulting algal blooms in Lake Byllesby. Reducing nutrient levels in the lake and in waters across Minnesota will mean changes in applying fertilizer on both cropland and city lawns. For cropland, on-farm research is important to fine-tuning those fertilizer applications.

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