On this page
- What is an inhibitor?
- The requirements for registering some inhibitor products
- Getting approval to undertake research or trials
- One-page summary of registration process
- The full inhibitor registration process
- How to prove your inhibitor works
- How to lodge your inhibitor in the Greenhouse Gas Inventory
- How you might streamline the inhibitor approval process
- Safety of environment inhibitors
What is an inhibitor?
An inhibitor is a substance, mix of substances or biological compound that mitigates adverse impacts of an agricultural activity on the environment, or mitigates emissions that contribute to climate change relating to plants or animals.
Inhibitors must be categorised as either agricultural chemicals or veterinary medicines. This is based on how they are to be used:
- Agricultural chemical-based inhibitors: These inhibitors are applied to pasture, horticulture, arable crops, or crops that may be used as animal feed. ‘Animal feed’ includes the situation where crop is fed to animals, such as silage or baleage, as well as the situation where animals graze the crop or forage in the field.
- Veterinary medicine-based inhibitors: These are inhibitors administered directly to the animal, such as a vaccine, in-feed or in-water treatment, or bolus.
The requirements for registering some inhibitor products
Anyone who wishes to import, manufacture, or sell a methane, urease, or nitrification inhibitor may need to have it registered under the Agricultural Compounds and Veterinary Medicines (ACVM) Act 1997. This will change to all types of inhibitor products once the ACVM Act is amended. Registration is to:
- identify and manage any risks that agricultural compounds (like inhibitors) could pose for public health, agricultural security, animal welfare, and trade of primary produce
- ensure that products are correctly labelled.
MPI will take the appropriate regulatory action if you import, market, or sell an unauthorised inhibitor product that requires registration.
Registering an inhibitor product can involve substantial technical expertise and input. If you or your company have limited experience of ACVM regulations and processes, you should consider employing a consultant to help you.
Products with novel active ingredients can take longer to process than known product types. Additionally, applicants are urged to engage with the Environmental Protection Authority (EPA), ACVM, and agricultural greenhouse gas teams as early as possible.
Do I need to register my urease inhibitor?
Urease inhibitors’ primary functions are to reduce nitrogen loss to the environment and decrease greenhouse gas production from the use of urea fertiliser. As urease inhibitors restrict conversion of urea to ammonium, urease inhibitors are often applied as a coating on urea. For practicality, inhibitor-coated urea fertiliser is often mixed with other fertilisers for simultaneous rather than separate application. The 2 main mechanisms for this mixing are:
- The manufacturer mixes the inhibitor-coated urea with set fertiliser components and sells this mixture under a trade name, or
- The end-user asks the manufacturer to produce a custom mix of inhibitor-coated urea (or the trade name product urease/fertiliser mixture) and other fertiliser components to meet their individual requirements.
An inhibitor coating ingredient may or may not need registration under ACVM, depending on the intended buyer. If a coating product is solely sold to a manufacturer, it is considered a manufacturing ingredient and does not need its own registration under ACVM. If the same coating product is intended for sale to the end-user, it requires registration under ACVM.
Use this table to help you work out registration requirements
| Requires registration | Does not require registration |
| Urease inhibitor alone, labelled for sale to end user | Urease inhibitor alone, for sale exclusively to manufacturer |
| Urea + urease inhibitor, formulated and labelled for direct sale to end user | Urea + urease inhibitor, as an ingredient for sale exclusively to manufacturer to include with other fertiliser components |
| Urea + urease inhibitor, mixed with other fertiliser components and labelled for end use | Custom mix of a registered product with other fertilisers – as a service when requested by end user |
Getting approval to undertake research or trials
If you want to limit the use of your inhibitor to research or trials, there are several ways to do this, depending on the type of product you have.
Products with an existing trade name can be approved for trial work under a 'provisional registration'. Follow the relevant guidelines.
ACVM guidance: Veterinary medicine trial approvals [PDF, 462 KB]
Other products may be exempted from registration under 'special circumstances' provisions.
You can find out about veterinary medicine research approvals under the special circumstances provisions in the guidance document.
ACVM guidance: Veterinary medicines trial approvals [PDF, 462 KB]
Authorisation generally depends on the applicant meeting certain conditions, which can include complying with an approved operating plan. Products can also be exempted from ACVM registration if they have been generally recognised as safe by MPI.
Find out about exemptions from registering an agricultural chemical
List of already exempted products – NZ Legislation
Research trials and animal re-entry into the food chain
Where inhibitors are intended for direct administration to animals or use on pasture, the trial work may require exposure of animals to experimental formulations. For these trials, there are no specific limits set by the ACVM team on the number or type of animals used – the applicant determines these details according to the needs of their inhibitor trial. The ACVM team will approve the total number of animals proposed for the intended trial work provided the risks related to the security of the trial site and animal use can be managed for larger trials.
Applicants can ask for withholding periods (WHPs) to be assigned for trial animals under the ACVM controls, and for food chain entry to be permitted under the Animal Products Act. To get these approvals, applicants need to provide enough formulation-specific and/or publicly available information to:
- assess residues in treated animals and their products
- assess the risks those residues may pose to trade and food safety
- clearly understand compound absorption, distribution, metabolism, and elimination when used as intended, and
- show trade-related risks can be managed with controls.
If there is not enough information available when ACVM receives the application to set WHPs under the ACVM Act, the trial approvals will specify that trial animals will be excluded from the food chain. If new information becomes available – such as results from preliminary residue trial work – applicants can apply for a change in controls to set WHPs and allow later food chain entry for those trial animals.
One-page summary of registration process
While we encourage you to read through all the guidance on this page before applying, we've also prepared a one-page summary of the ACVM application process.
ACVM inhibitor registration process [PDF, 142 KB]
Documents about inhibitor registration and regulations
Regulatory control of agricultural compounds in New Zealand [PDF, 322 KB]
Overview of risk management under the ACVM Act 1997 [PDF, 269 KB]
ACVM inhibitor frequently asked questions [PDF, 377 KB]
