Farm Progress

Private wells in more than 300 townships will be tested as part of MDA’s Nitrogen Fertilizer Management Plan.

Paula Mohr, Editor, The Farmer

June 6, 2017

3 Min Read
WATER CHECK: Private wells in five Minnesota counties will be tested this summer for nitrate levels.ceazars/iStock/Thinkstock

Private well testing in selected Minnesota townships continues this year as a component of the state’s revised Nitrogen Fertilizer Management Plan.

The plan, developed over several years with input from the ag community and revised in 2015, calls for an assessment of nitrate-nitrogen concentrations in private wells. The Minnesota Department of Agriculture has identified townships throughout the state with significant row crop production that are vulnerable to groundwater contamination and has prioritized them for testing. Other townships may be added if there are data to suggest a local groundwater problem.

Nitrate leaching from fertilizer is a challenging problem for farmers. On average, 19% of Minnesota’s cropland — 1 in 5 acres — overlies vulnerable groundwater resources statewide, according to MDA.

More than 70,000 private well owners will be offered nitrate testing in more than 300 townships (35 to 59 townships per summer) by 2019. Work will be done in partnership with local governments across the state.

This summer, townships in Clay, Goodhue, Wabasha, Rice and Fillmore counties are being tested, says Allen Sommerfeld, MDA senior communications officer. Private well owners are being notified by mail that they will be receiving a free water sample kit, along with a letter explaining the program. If homeowners choose to participate, they take the sample and send it to the lab in the prepaid mailer.

If nitrate is detected in the initial sample, the homeowner is offered a follow-up nitrate test, pesticide test and well site visit the following summer. Trained MDA staff visit participating homeowners the following year to resample the well and conduct a site assessment. The site assessment helps to identify possible non-fertilizer sources of nitrate, and wells with construction problems that may make them more susceptible to contamination. All sampling is voluntary on the part of homeowners, Sommerfeld says.

Thus far, approximately 20,042 wells in 167 townships were sampled from 2013-16. Seventy-one of the tested townships have 10% or more of their wells over the health risk limit of 10 milligrams per liter for nitrate-N. In 53 tested townships, less than 5% of wells were over the health risk limit. Overall, 9.5% of the 20,042 wells tested exceed 10 mg/L during the initial sampling.

More information about the township testing program is available.  Nitrate results from several counties are available as well.

MDA, as part of the NFMP, is developing new rules to reduce and prevent high nitrate levels in vulnerable groundwater areas. All together, these proposed rules will be called the Nitrogen Fertilizer Rule.

Sommerfeld says MDA is hoping to release a draft soon for public comment.

The proposed rule has two parts. Part 1 would restrict the application of fall N to frozen soils in areas vulnerable to groundwater contamination. Restrictions would be based on land features, such as coarse textured soils, karst soils and shallow fractured bedrock.

Part 2 would focus on areas with high nitrates and following nitrogen fertilizer best management practices.

The nitrogen fertilizer rule should be finalized around August 2018.

For information about the proposed rule, visit MDA's Nitrogen Fertilizer Rule webpage.


About the Author(s)

Paula Mohr

Editor, The Farmer

Mohr is former editor of The Farmer.

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