Nitrogen Stabilizer Products that Must Be Registered under FIFRA

• Federal requirement to register pesticides
• FIFRA definition of nitrogen stabilizer
• Discussion of definition
• Substances excluded from the definition of a nitrogen stabilizer
• Federal pesticide registration

Federal Requirement to Register Pesticides

The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requires that all pesticides sold or distributed in the United States (including imported pesticides) be registered by the U.S. Environmental Protection Agency (EPA) except where exempt from registration requirements. EPA’s registration process and associated requirements are discussed on EPA’s website.

This EPA guidance explains existing statutory and regulatory provisions regarding nitrogen stabilizers. It does not create any new requirements or exemptions from the requirements of FIFRA.

FIFRA Definition of Nitrogen Stabilizer

FIFRA Section 2(u) defines pesticides that must be registered under FIFRA to include “any nitrogen stabilizer.” FIFRA Section 2(hh) defines a nitrogen stabilizer, as follows:

"The term “nitrogen stabilizer” means any substance or mixture of substances intended for preventing or hindering the process of nitrification, denitrification, ammonia volatilization, or urease production through action upon soil bacteria. 

Such term shall not include

1. dicyandiamide;
2. ammonium thiosulfate; or 
3. any substance or mixture of substances:

   1. that was not registered pursuant to section 3 prior to January 1, 1992; and

   2. that was in commercial agronomic use prior to January 1, 1992, with respect to which after January 1, 1992, the distributor or seller of the substance or mixture has made no specific claim of prevention or hindering of the process of nitrification, denitrification, ammonia volatilization [or] urease production regardless of the actual use or purpose for, or future use or purpose for, the substance or mixture. 

Statements made in materials required to be submitted to any state legislative or regulatory authority, or required by such authority to be included in the labeling or other literature accompanying any such substance or mixture shall not be deemed a specific claim within the meaning of this subsection.”

Discussion of Definition

Nitrogen is one of the primary nutrients for plant growth, development and reproduction; the main inorganic forms of nitrogen in soils are ammonium and nitrate. A nitrogen stabilizer is any substance or mixture of substances intended for preventing or hindering the process of nitrification, denitrification, ammonia volatilization, or urease production through action upon soil bacteria. A brief explanation of each process follows:

• Nitrification is the part of the nitrogen cycle where soil organisms convert ammonia and ammonium to nitrite and then to nitrate-nitrogen which is available to plants. Nitrate is the form that can be moved out of the soil by leaching or lost by denitrification.
• Denitrification is the bacterial conversion and loss of nitrate-nitrogen to nitrogen gas.
• Ammonia volatilization refers to ammonia nitrogen loss.
• Urease is an enzyme produced by bacteria in the soil and contributes to the conversion of urea to ammonia, which can be lost through volatilization.

Nitrification, denitrification, ammonia volatilization, and urease production denote specific undesirable actions of soil bacteria with the result that nitrogen availability is decreased.

The first item to consider in evaluating whether a product is a nitrogen stabilizer is if such a product accomplishes the purpose of nitrogen stabilization through action upon soil bacteria. The soil bacteria that convert nitrogen nutrients to nitrogen gas are considered to be pests. Substances that prevent or hinder the process of nitrification, denitrification, ammonia volatilization, or urease production through a mechanism other than action on soil bacteria are not nitrogen stabilizers.

Under 40 CFR §152.6(b)(1), living organisms are not considered to be substances. Thus a product cannot be a nitrogen stabilizer if its action depends solely on a living organism. To be subject to FIFRA, the product would also have to contain something other than a living organism that performs those functions.

EPA has identified certain phrases as claims that a product prevents or hinders the process of nitrification, denitrification, ammonia volatilization, or urease production. Under 40 C.F.R. § 152.6(b)(4), these claims include:

• Improves crop utilization of applied nitrogen.
• Reduces leaching of applied nitrogen or reduces groundwater nitrogen contamination.
• Prevents nitrogen loss.
• Prolongs availability of nitrogen.
• Increases nitrogen uptake, availability, usage, or efficiency.

Such claims indicate that the substance has a mechanism involving action on soil bacteria. Any product that makes nitrogen stabilizer claims as listed in 40 CFR §152.6 will be presumed in the first instance to be a nitrogen stabilizer. If the producers of such products disagree, they must demonstrate that the product accomplishes its effects without affecting soil bacteria. By considering the product’s claims, composition and mode of action, EPA determines whether a product bearing such claims is a nitrogen stabilizer.

In summary, when a product that includes a substance makes nitrogen stabilizer claims, acts on soil bacteria, and is not otherwise excluded from the statutory definition of a nitrogen stabilizer or exempt under 40 CFR Part 152, then the product is a pesticide and must be registered by EPA.

Substances Excluded from the Definition of a Nitrogen Stabilizer

FIFRA Section 2(hh) excludes specific substances, as well as substances that meet certain criteria, from the definition of a nitrogen stabilizer. The substances that are specifically excluded are:

• dicyandiamide; and
• ammonium thiosulfate.

As discussed in 40 CFR §152.6(b), a nitrogen stabilizer is excluded from regulation under FIFRA if the substance (or mixture of substances), meets all four of the following criteria:

1. The substance prevents or hinders the process of nitrification, denitrification, ammonia volatilization, or urease production through action affecting soil bacteria and is distributed and sold solely for those purposes and no other pesticidal purposes. For purposes of this section, living organisms are not considered to be substances, and the actions of living organisms are not relevant to whether a substance is deemed to be a nitrogen stabilizer.
2. The substance was in ‘commercial agronomic use’ in the United States before January 1, 1992. EPA considers a substance to be in commercial agronomic use if it is available for sale or distribution to users for direct agronomic benefit, as opposed to limited research, experimental or demonstration use.
3. The substance was not registered under FIFRA before January 1, 1992.
4. Since January 1, 1992, the distributor or seller has made no claim that the product prevents or hinders the process of nitrification, denitrification, ammonia volatilization or urease production. EPA considers any of the following claims (or their equivalents) to be a claim that the product prevents or hinders nitrification, denitrification, ammonia volatilization or urease production:
   1. Improves crop utilization of applied nitrogen.
   2. Reduces leaching of applied nitrogen or reduces groundwater nitrogen contamination. 

   3. Prevents nitrogen loss. 

   4. Prolongs availability of nitrogen.

   5. Increases nitrogen uptake, availability, usage of efficiency.

In addition, a product will be considered to have met the criterion in 40 CFR §152.6(b)(4) that no nitrogen stabilization claim has been made if:

1. the nitrogen stabilization claim, in whatever terms expressed, is made solely in compliance with a state requirement to include the claim in materials required to be submitted to a state legislative or regulatory authority, or in the labeling or other literature accompanying the product; and 

2. the state requirement to include the claim was in effect both before the product bearing the claim was introduced into commercial agronomic use, and before the effective date of this rule [February 12, 2002].

A product that meets all of the criteria of this paragraph with respect to one state is not thereby excluded from FIFRA regulation if distributed and sold in another state whose nitrogen stabilization statement requirement does not meet the requirements of paragraph (b)(5)(ii) of this section. In other words, if the product is also distributed and sold in another state that does not require a nitrogen stabilizer claim but the product nonetheless makes a nitrogen stabilizer claim in the second state, the product is considered a pesticide under FIFRA. Sale or distribution of the product in any state, including the state which imposed the requirement to make the nitrogen stabilizer claim, is subject to the provisions of FIFRA. 

Finally, 40 CFR §152.20, §152.25 and §152.30 discuss exemptions to registration for pesticides:

• that are adequately regulated by another federal agency;
• of a character not requiring FIFRA regulation; and
• that may be transferred, sold or distributed without registration.

However, these exemptions are not specific to nitrogen stabilizers.

Federal Pesticide Registration

Find additional information on federal pesticide registration.