The state of Arizona has legislatively mandated Best Management Practices (BMPs) for nitrogen (N) fertilizer use. The statue was first enacted in 1991 and has undergone several revisions since then. The specifics of the legislation under the most recent authorization (Title 49-247) can be found in reference 113. The agency authorized to oversee the administration of the state’s N fertilizer use BMP program is the Arizona Department of Environmental Quality (ADEQ).

Within this program, entities using N fertilizers for agricultural purposes will, by default, be assigned a “General Permit” designation unless they opt out. In other words, the BMP mandate provides that agricultural N-fertilizer users who adopt the BMP requirements do not need to submit a formal application to receive the “General Permit” designation. However, special authorization is required to obtain exemptions from implementation of the BMP requirements. Furthermore, if the authorization under the general permit category of an agricultural N-fertilizer user is revoked for non-compliance, the entity will be required to seek a special permit under title 49-241 (114) for continued use of N fertilizers. 

The program recognizes that specific BMPs vary across agriculture systems within the state and considerations can be given to accommodate economic feasibility of implementing the BMP requirements under varied settings. The ADEQ may seek to revisit the statues, as needed, in consultation with an advisory board consisting of stakeholders, regulators, and experts.

The state-mandated Best Management Guidelines for N fertilizer use, within the general permit category, are provided under Title 18, Chapter 9, Article 4 (R18-9-402) (reference 115). A summary of the guidelines is presented here for convenience:

An owner or operator may apply a nitrogen fertilizer under the general permit without submitting a notice to ADEQ, if the owner or operator complies with the following best management practices:

1. Limit application of fertilizer so that it meets projected crop needs;
2. Time application of the fertilizer to coincide with maximum crop uptake;
3. Apply the fertilizer by a method designated to deliver nitrogen to the area of maximum crop uptake;
4. Manage and time application of irrigation water to minimize nitrogen loss by leaching and runoff; and
5. Use tillage practices that maximize water and nitrogen uptake by a crop or plant.

The N fertilizer management recommendations presented on this webpage are consistent with many of the general permit BMP guidelines summarized here. While soil and plant testing requirements are not explicitly stated in the general permit guidelines, it is clear that they are implicitly required on the mandate that fertilizer application rates be limited to the projected crop needs. 

The author of this report is not aware of any instance where an operation under a general permit has been revoked for non-compliance. However, the author is also not aware of compliance verification audits by ADEQ. For practical reasons, compliance may be presumed unless adverse environmental effects traceable to an agricultural operation occur. Nevertheless, if an inspection were to be conducted, growers would be required to provide proof of compliance to ensure continued operation under the general permit category.