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What is an inhibitor?

An inhibitor is a substance, mix of substances or biological compound which mitigates adverse impacts of an agricultural activity on the environment, or mitigating 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 are inhibitors applied to pasture or feed crops, or crops that may be used as animal feed. This would include the situation where animals would graze the treated crop or forage.
  • 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.

Find an ACVM consultant

One-page summary of registration process

While we encourage you to read through all the guidance on this page before making an application, 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

Guide to the new rules for inhibitors (2023) [PDF, 734 KB]

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, 378 KB]

The inhibitor registration process

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How to prove your inhibitor works

To register your inhibitor, you need to prove that it mitigates adverse environmental impacts associated with agricultural activity, and provide reliable metrics which show the amount of greenhouse gases or nitrates reduced through the use of your inhibitor. This is normally done through scientifically controlled research or trials. Our flowchart has more guidance about this.

How to prove that your inhibitor works (flowchart) [PDF, 88 KB]

Note: If your inhibitor is intended to reduce greenhouse gases, you should not assume that registration automatically qualifies it for inclusion in the National Greenhouse Gas Inventory.

Find out more about proving and quantifying the efficacy of your inhibitor 

Demonstrating efficacy for methane inhibitors [PDF, 284 KB]

Demonstrating efficacy for urease/nitrification inhibitors [PDF, 365 KB]

How to lodge your inhibitor in the Greenhouse Gas (GHG) Inventory

You may need to have your inhibitor lodged in the GHG Inventory if:

  • your inhibitor is intended to reduce greenhouse gases, and
  • you want users of your product to financially benefit from this (by reducing their GHG emissions levy liabilities).

The acceptance of your inhibitor for the purposes of the GHG Inventory is not guaranteed by registration under the ACVM Act. We recommend talking early with the GHG Inventory team. Meeting GHG Inventory requirements at the same time you're preparing the data needed for ACVM registration, could be beneficial. Email the team on GHGInventory@mpi.govt.nz

Flowchart for including your inhibitor in the GHG Inventory [PDF, 113 KB]

Find out more about the GHG Inventory

The national framework for data collection and reporting GHG emissions 

How you might streamline the inhibitor registration approval process

It may be possible to reduce the time and effort involved in making an application.

  • There are opportunities for reducing data requirements under certain circumstances. For example, if your inhibitor is the same or similar to an already registered product.
  • You may be able to use overseas data (either partially or whole) to support certain requirements such as target animal safety.

Check all the opportunities to streamline your application [PDF, 84 KB]

Find out more about streamlining an inhibitor application

Provisional registration of an inhibitor

Making a case to provide less or different information to that normally required by MPI [PDF, 107 KB]

Who to contact

If you have questions about inhibitors and the ACVM Act, email approvals@mpi.govt.nz

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