Iowa fertilizer management standards updated
Iowa farmers now have new standards for managing fertilizers, including application. The USDA’s Natural Resources Conservation Service released the new standards this week in a 11-page nutrient management document.
The new document offers farmers guidance on managing fertilizer rates, source, placement and timing of application.
Although the standards are updated every year, NRCS accepted comments on the standards for more than a year and carefully considered changes, NRCS said in a news release.
The 2013 standards have important changes compared to the 2008 version. These changes reported by the Des Moines Register include:
• Changes to “sensitive” areas. Several changes were made to the nutrient application criteria to minimize the contamination risk near water quality “sensitive areas.” Recognizing that water entering tile inlets often runs directly to a stream, they are now considered a water quality sensitive area.
A 50-foot 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 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 and MAP/DAP, are included in this criteria for fall application.
• Rescue Nitrogen Application OK. Untimely heavy spring rains caused farmers to lose large amounts of nitrogen the past several years. A new provision allows farmers 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.
• 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.