Strategic Farming: Let’s talk crops! focuses on soil fertility adjustments for 2022

UMN Extension
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With high fertilizer prices following the 2021 drought, many farmers and agricultural professionals are looking to adjust their nutrient management practices for the 2022 crop.

Historically, nitrate concentrations in surface water can spike following a drought, said Brad Carlson, Extension educator in water quality. While an environmental concern, it also indicates that residual nitrate is still in the soil profile.

"The question is, can we keep that nitrate out of the surface water?” Carlson said. “In light of the high fertilizer prices, we have the ability to utilize that residual nitrate as part of the total fertility package going into 2022.”

Because nitrate is mobile in the soil and it cycles quickly, soil nitrate testing may be a helpful tool in managing residual nitrate. There are two scenarios where the University of Minnesota highly recommends taking a preplant soil nitrate test: The first is in fields with long-term manure application histories, because of the increased potential for organic matter to mineralize. Corn on corn is the second situation where soil nitrate tests are highly recommended.

Carlson also addressed the role of nitrogen stabilizers for 2022. Nitrification inhibitors, products that slow the fertilizer’s conversion to nitrate, may not play much of a role this coming spring. Urease inhibitors, on the other hand, reduce volatilization losses and are very beneficial when there’s a low amount of water to move urea into the soil or when the urea was shallowly incorporated. “Unless you’re banding or incorporating the urea three to four inches in the soil to begin with, urease inhibitors are a fairly good investment,” Carlson says.

With high fertilizer costs, soils with medium to high levels of phosphorus and potassium offer producers some flexibility in their fertilizer applications, according to Dan Kaiser, Extension nutrient management specialist. “The average phosphorus test decrease without fertilizer applications is roughly two parts per million per year with the Bray soil test,” says Kaiser. “If you have an in-furrow starter, you can go a long way with solid, high soil test values.”

University of Minnesota’s Strategic Farming: Let’s talk crops! webinar series, offered Wednesdays through March, features discussions with specialists to provide up-to-date, research-based information to help farmers and ag professionals optimize crop management strategies for 2022. Join us next week for “2021-The year when past indiscretions were revealed (think compaction).” For more information and to register, visit z.umn.edu/strategic-farming.

For more information on fertilizer and soil nitrate testing recommendations from the University of Minnesota Extension, visit extension.umn.edu/nutrient-management.

Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research and Promotion Council for their generous support of this program.

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