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2013 Nutrient Management Standard Released in Iowa

USDA’s Natural Resources Conservation Service (NRCS) recently released the new Iowa Nutrient Management Conservation Practice Standard – the guiding document for implementing nutrient management plans for Iowa farmers.

Iowa’s 11-page Nutrient Management (NM) or 590 Standard provides farmers guidance regarding managing the rate, source, placement, and timing of the application of plant nutrients and soil amendments. This includes animal manure, commercial fertilizer, legume credits, green manure, and crop rotations. The Standard is updated every five years.

According to Eric Hurley, Iowa NRCS nutrient management specialist, the Nutrient Management Practice Standard helps farmers and the state’s natural resources. “The Practice Standard helps farmers plan nutrients for optimal crop production and fully utilize manure or organic byproducts as plant nutrient sources,” he says. “It also protects water quality by minimizing agricultural nonpoint source pollution and helps improve soil health.”

The National Laboratory for Agriculture and the Environment in Ames, IA, led a comprehensive revision effort, according to Hurley, with input from Iowa State University (ISU). They sought and utilized input from agricultural organizations, environmental groups, private agronomists, and other stakeholders.

Compared to the 2008 Iowa version, the 2013 version has some important changes, including:

·        Changes to “sensitive” areas. Several changes were made to the nutrient application criteria to minimize the contamination risk near areas deemed sensitive from a water quality standpoint. A 50-ft. filter strip can be used in place a of a 200-foot setback when surface applying nutrients near sensitive areas. As an interim mitigation practice near areas such as tile inlets, cover crops or a no-till cropping system may be used to mitigate runoff risk. The application criteria now apply to most nitrogen and phosphorus sources, not just manure.

·        New 50 Degrees or Below Provision. Iowa farmers have always been encouraged to wait to apply fall anhydrous ammonia until soil temperatures reach 50 degrees, trending colder. Now other high- ammonium sources, such as liquid swine manure, are included in these criteria for fall application.

·        Rescue Nitrogen Application is OK. Untimely heavy spring rains caused farmers to lose large amounts of nitrogen over the past several years. A new provision allows farmers to utilize a “Rescue Nitrogen Application” that permits an additional nitrogen application when weather causes a significant loss of nitrogen. The Standard specifies ways to formulate and evaluate management alternatives for rescue nitrogen applications. “Even with good management, farmers can lose nitrogen when excessively heavy rains hit their fields,” says Hurley. “Many of Iowa’s field agronomists requested this provision be included in the standard, and for good reason.”

·        Additional Practices for Controlling and Trapping Nutrients. To help trap nitrogen, conservation practices such as cover crops, filter strips, bioreactors, and nutrient treatment wetlands (CREP wetlands) were added to the practice list. To control and trap phosphorus, practices such as no-till, terraces and grassed waterways that control erosion and trap sediments are included.

·        Equipment Calibration. Equipment used to apply fertilizer and manure must be calibrated to assure that what is planned to be applied is actually applied. This provision is included in the Operation and Maintenance section of the Standard. Lori Schnoor, district conservationist for NRCS in Jackson County, IA, says calibrating manure spreader equipment, for example, will benefit producers both economically and environmentally. “It may take extra time to calibrate equipment, but in the long run it will save you money,” she says.

·        Yield Goal Now Realistic Yield Potential. Any reference in the old standard to “Yield Goal” was changed to “Realistic Yield Potential” in the new standard. This change provides for simpler ways to estimate yield to determine nutrient removal rates.

·        Manure Testing Requirement. A lab certified through the Minnesota Dept. of Agriculture Manure Testing Laboratory Certification Program (MTCP) will be used to complete manure tests. Learn more at

·        Biosolids Included as Plant Nutrients. Biosolids like sludge and food processing waste are now included as sources of plant nutrients, recognizing that they are also a valuable fertilizer source.

·        Guidance for Adaptive Nutrient Management. This provision encourages producers to conduct on-farm research to make better nutrient management decisions. “We encourage farmers to set up their own on-farm strip trials to test nutrient management practices,” says Hurley.

The Iowa Nutrient Management Standard is available on the Iowa NRCS website at Click on the “Iowa Conservation Practice Standards” link under “Helpful Links” on the home page to learn more.

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