Ankeny, Iowa — Members of Agriculture’s Clean Water Alliance (ACWA) have reaffirmed their annual commitment to protect Iowa’s soil and water.

At their recent board meeting, ACWA members agreed to the Environmental Code of Practice for Nitrogen Fertilization, which states they will delay fall anhydrous applications without a nitrification inhibitor until soil temperatures are 50 degrees Fahrenheit and trending lower. This reduces nitrate loading from farm fields into Iowa’s rivers and streams, helping to protect the state’s water resources.

“Since ACWA’s founding in 1999, we have united and agreed to this Code of Practice. It has been a requirement of membership since 2001,” said Dan Dix, NEW Cooperative general manager and ACWA president. “Because of our members’ locations, ACWA’s footprint covers more than 70 percent of the state, enabling the Code of Practice to have a greater impact on water quality than ever before.”

ACWA uses the county soil temperature and forecast maps published by Iowa State University Extension and the ISU College of Agriculture and Life Sciences as a decision tool for beginning fall fertilizer applications. The maps can be found at:

Members self-report to ACWA to validate their conformance to the Code of Practice, which takes place usually in mid to late October, depending on the region. Colder soils hinder the conversion of ammonium nitrogen to nitrate, which reduces leaching or denitrification and keeps ammonium in the soil.

In addition, AWCA members encourage the use of nitrogen stabilizers, slow-release fertilizers, incorporation or injection, soil nitrate testing and other tools that minimize loss of nitrogen to water sources. Farmers and landowners can implement conservation practices such as no-till, cover crops, bioreactors and saturated buffers, which keeps nutrients and soil in farm fields and reduces loading into waterbodies.

ACWA also endorses 4R Plus, which focuses on nutrient stewardship using the Right Source of fertilizer, at the Right Rate, Right Time, and Right Place. The Plus refers to conservation farming practices for soil health and water quality improvement. Led by the Nature Conservancy, 4R Plus is guided by a coalition of agricultural and conservation organizations to support farmers’ efforts to implement these practices.

“ACWA members are dedicated to helping farmers manage nutrients to enhance both environmental quality and crop production,” said Roger Wolf, ACWA Executive Director. “Through ACWA’s projects and partnerships, the organization is making a greater impact on Iowa’s water quality for our farmers, landowners and urban residents.”

For more information about the ACWA and the Code of Practice, visit For more information about 4R Plus, visit


Agriculture’s Clean Water Alliance (ACWA) is a non-profit association whose mission is identifying and advancing solutions that reduce nutrient loss, build healthier soils, and improve Iowa’s waters. ACWA is recognized for its ability to build upon its members’ extensive relationship with farmers across Iowa.

Regular members include: AgState, Gold-Eagle Cooperative, Heartland Co-op, Helena Agri-Enterprises, Landus Cooperative, NEW Cooperative, Inc., Nutrien Ag Solutions, Pro Cooperative, Van Diest Supply

ACWA 2022 Code of Practice for Nitrogen Fertilization
Purpose: To establish reasonable and practicable guidelines for nitrogen fertilization applications to reduce nitrate loss from farm fields.

Why:Effective management of nutrients on farms in the watershed is one of the keys to enhancing both environmental quality and profitable crop production. Consistent with the Iowa Nutrient Reduction Strategy, this Code of Practice provides information about guidelines adopted by the ACWA members as a condition of membership.
Application Guidelines & Self ‐ Reporting:A nutrient budget for nitrogen, phosphorus and potassium shall be developed that considers all potential sources of nutrients including manure, legumes, etc. Nutrient recommendations shall be based on current soil test results, realistic yield goals, environmental impact, and producer management capabilities.Use one of two methods to document soil temperature at the time of application decision:Standardized county temperature and forecast maps found at” in‐field soil temperature check and reading recording method used on self‐reporting formDelay fall anhydrous applications without a nitrification inhibitor until soil temperatures are 500 F, trending lowerUse On‐line ACWA Self‐Reporting System to document conformance with requirement:Regular ACWA Board Member assigns staff responsibility to report start of application for all counties within member trade area.Self‐reporting system is on‐line at: ACWA Self Recording Form (a specific username and password has been assigned for each member organization). Simple, easy, takes less than 1‐minute to complete on computer, cell phone, or other electronic devices.Any questions contact: Roger Wolf, ACWA Executive Director, 515‐205‐9225 or Kristen Dearden, ACWA Membership Services & Outreach Manager, 515‐334‐1482.Regardless of time of year application occurs, encourage use of other supporting nutrient management technologies such as stabilizers, slow‐release fertilizers, incorporation or injection, soil nitrate testing and other technologies that minimize loss to surface or ground water resources.If producer is participating with USDA Conservation Programs additional considerations for producer conformance with NRCS 590 Nutrient Management standard shall be followed. For guidance and requirements see standard: 590 Nutrient Management ( Encourage use of other supporting practices where feasible:Tile line denitrification bioreactorConstructed wetlandConservation stream buffer and/or saturated buffer stripsFall cover cropping system