Code of Practice for Nitrogen Fertilization
ACWA 2023

Download the 2023 Code of Practice

Purpose: To establish and implement reasonable and practical 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

  1. A nutrient recommendation for nitrogen and phosphorus 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.
  2. Use one of two methods to document soil temperature at the time of application decision:
  3. Delay fall anhydrous applications without a nitrification inhibitor until soil temperatures are 50⁰ F, trending lower
  4. Use the online ACWA Self-Reporting System to document conformance with the requirement:
    • Regular ACWA Board Member assigns staff responsibility to report the start of application for all counties within the member trade area.
    • Self-reporting system is online at: ACWA Self Recording Form (a specific username and password have been assigned for each member organization). Simple, easy, and takes less than 1-minute to complete on a computer, cell phone, or other electronic devices.
    • Any questions, contact Roger Wolf, ACWA Executive Director, or at 515-205-9225, or Kristen Dearden, ACWA Membership Services & Communication Coordinator, 515-334-1482.
  5. Regardless of the time of year application occurs, encourage the 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 groundwater resources.
  6. If the producer is participating with USDA Conservation Programs additional considerations for producer conformance with NRCS 590 Nutrient Management standards shall be followed.  For guidance and requirements see standard: 590 Nutrient Management (
  7. Encourage the use of other supporting practices where feasible:
    • Tile line denitrification bioreactor
    • Constructed wetland
    • Conservation stream buffer and/or saturated buffer strips
    • Fall cover cropping system