by Phyllis Bongard, Educational content development and communications specialist
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| Soil sampling for the PSNT test. |
Watch a video recording of the webinar below, and check out some highlights with links below the video.
Nitrogen adjustments
Capturing residual nitrate
Historically, nitrate concentrations in surface water can spike following a drought. While an environmental concern, it also indicates that residual nitrate is still in the soil profile.In light of the high fertilizer prices, you may have the ability to utilize that residual nitrate as part of your 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 this spring. 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 mineralization. Corn on corn is the second situation where soil nitrate tests are highly recommended. For more information, see the section on soil nitrate tests in Fertilizing corn in Minnesota.
Role of nitrogen stabilizers in 2022
What role might nitrogen (N) stabilizers play in 2022? Nitrogen inhibitors delay N transformations and include two groups: Nitrification inhibitors - products that slow the conversion of N fertilizers to nitrate; and urease inhibitors – products that delay the conversion of urea to ammonia, which is then lost to the atmosphere.These products do degrade over time and that rate increases with warm temperatures. For example, a nitrification inhibitor applied in early spring will have likely worn off by the time the crop is taking up significant N. Nitrification inhibitors may not play a significant role in spring 2022.
However, urease inhibitors can be beneficial when there’s a low amount of water to move urea into the soil or when it’s shallowly incorporated. Unless you’re banding or incorporating urea at least three to four inches, urease inhibitors are a fairly good investment.
For more information, see Spring fertilizer decisions: Should you use nitrogen inhibitors and other enhanced efficiency fertilizers?
Pre-sidedress nitrate test (PSNT)
The PSNT is a tool to help determine whether or not supplemental N is needed. It can be useful in fields that have a large potential for mineralization, including fields that have a manure history, are coming out of alfalfa or those with substantial carryover from the previous year. However, the PSNT must be carried out correctly to get the most out of it. See Tips for accurate pre-sidedress nitrate tests.Phosphorus and potassium
With high fertilizer prices, medium to high soil test levels of phosphorus and potassium offer producers some flexibility in their fertilizer applications. Applying in-furrow starter instead of broadcasting P will carry you a long way in high testing soils. Potassium application is trickier, especially in dry years as starter application may not be enough if soils test less than 200 ppm. Read the discussion on changes in P and K soil test values in "Fertilizing corn in Minnesota."Join the webinar series
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 this week when Dr. Aaron Daigh, NDSU, and Jodi DeJong-Hughes, Extension educator, discuss 2021: The year when past indiscretions were revealed (think compaction).
For more information and to register, visit z.umn.edu/strategic-farming.
Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!
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