Greenhouse Nutrient Feedwater Regulation

Table of Contents

  1. Introduction
  2. Roles of the two ministries responsible
  3. Overview of the regulation
  4. Environmental protection
  5. Resources
  6. More information


Many greenhouse operations use circulation systems to deliver water and fertilizer to greenhouse crops that are grown without the use of soil. Some greenhouses use closed circulation systems that re-use the nutrient-rich water, or nutrient solution, continuously (Figure 1).

There are times when the nutrient solution is no longer suitable for growing greenhouse crops. At this point, the nutrient solution can be removed and used to fertilize other agricultural crops. Greenhouse nutrient feedwater (GNF) is the nutrient solution removed from a closed circulation system at a greenhouse operation that is registered under the Greenhouse Nutrient Feedwater Regulation, O. Reg 300/14 (the regulation). GNF still has nutrient value suitable for certain crops. Re-using the material is a good option for some growers.

A closed circulation system. Greenhouse nutrient feedwater is the nutrient solution that is removed from the closed circulation system of a registered greenhouse.

Figure 1. A closed circulation system. Greenhouse nutrient feedwater is the nutrient solution that is removed from the closed circulation system of a registered greenhouse.

The regulation, made under the Nutrient Management Act, 2002 (NMA), sets out the rules for managing GNF generated by a registered greenhouse, including rules on storage, transportation and land application. The regulation is effective as of January 1, 2015. You can read the full regulation on the e-Laws website.

The Greenhouse Nutrient Feedwater Regulation gives greenhouse growers another tool to use to comply with environmental standards. Other than the NMA, greenhouse operations can choose to:

  • apply the nutrient solution on land under an Environmental Compliance Approval (ECA)
  • treat and discharge the nutrient solution using an approved sewage works
  • dispose of the nutrient solution at an approved waste disposal site using an approved waste hauler
  • discharge the nutrient solution to a sanitary sewer
  • discharge the nutrient solution to a septic system

These options are managed under legislation other than the NMA. See the "more information" section below for information on who you can contact about each of these options.

The regulation adopts the Greenhouse Nutrient Feedwater Management Protocol and the Greenhouse Nutrient Feedwater Sampling and Analysis Protocol. These protocols outline the rules of the regulation, and rules that are in addition to those written in the regulation. The requirements of the protocols are part of the regulation and are legally enforceable. The protocols outline requirements such as:

  • GNF application rates
  • what greenhouse operation must provide when they register under the GNF Regulation
  • what must be provided in GNF strategies, GNF plans, land application schedules and records of land application
  • sampling and analysis requirements

Roles of the two ministries responsible

The NMA and O. Reg 300/14 are managed by the Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and enforced by the Ministry of the Environment and Climate Change (MOECC). Environmental protection is a top priority for both ministries.


  • is responsible for approvals, training, education and outreach under the NMAaccepts registration and strategy submissions, and approves GNF plans


  • works with the greenhouse sector to improve environmental performance
  • carries out proactive inspections of greenhouses to ensure compliance with the regulation and protection of the environment
  • is responsible for enforcing compliance with the OWRA, the EPA and the NMA

Overview of the regulation

  • The regulation applies to greenhouse operations generating GNF and that choose to register under the regulation.
  • The regulation outlines how to manage the GNF generated from a registered greenhouse, including:
    • transportation of GNF between agricultural operations, including the piping of GNF
    • rules for how farmers can land apply and store GNF they receive from registered greenhouses

The regulation was developed based on an analysis of the risks posed by GNF application to land, the risk of nutrients entering waterways and the potential benefits for agricultural crops. The regulation:

  • supports the economically sustainable growth of Ontario's agri-food industry, specifically the Ontario greenhouse sector
  • provides greenhouse operators with another option to manage GNF in a way that is protects the environment
  • provides clear, predictable rules for the greenhouse sector
  • encourages greenhouse operations to use sustainable operational practices with the option to reduce, re-use and recycle GNF
  • reduces approval costs for greenhouses and costs for farmers receiving GNF
  • provides farmers with a new source of nutrients they can use to fertilize crops

Amendments to O. Reg. 525/98 under the OWRA exempt greenhouse operations that register under the GNF Regulation from requiring an Environmental Compliance Approval (ECA) for sewage systems that only manage GNF (outlined in s. 53 of the OWRA). This is to ensure there is no regulatory duplication. The OWRA regulates the direct discharge of GNF to groundwater or surface water.

Part III of the regulation and Part 3 of the Greenhouse Nutrient Feedwater Management Protocol set out the rules for greenhouses operations that wish to register under the NMA. Greenhouse operations must prepare their registration in a form specified by the Director and submit it to the Director. The registration must contain all information required by Part III of the regulation and Part 3 of the protocol. If the operation has five or more nutrient units, a GNF strategy must also be submitted at the same time as the registration of the greenhouse operation. The strategy:

  • indicates how the nutrients will be stored
  • identifies the agricultural operation that will receive the GNF
  • must be prepared by a person who meets the requirements set out in the regulation
  • must be updated and resubmitted to OMAFRA annually

Environmental protection

Protecting the Great Lakes and other waterways is an important way to make sure that everyone has access to safe drinking water, clean beaches and a healthy environment. The GNF Regulation helps to protect the Great Lakes by providing greenhouse operators with a cost-effective option to manage GNF in a way that reduces the amount of phosphorus entering out waterways. There are many ways the regulation protects our waterways, including:

  • requiring application setbacks from watercourses and wells
  • prohibiting application to frozen or snow-covered land
  • requiring agricultural operations to carry out sampling and analysis of soil as part of the preparation of a GNF plan
  • establishing annual, daily and hourly application rate limits
  • restricting land application from December to March when there is higher risk to the environment
  • ensuring permanent GNF storage facilities are maintained to minimize leakage


OMAFRA developed a series of web pages that provides brief overviews of the regulation as it applies to:

Risks related to GNF management processes selected

There are a number of options available that meet the requirements of the GNF Regulation. If you register under the regulation, you need to understand that in some cases certain options selected may have negative impacts if processes do not work out as planned. An example of this is if you choose the 24-month GNF generation option and do not install a GNF storage (which is allowed in the regulation). If for some reason you generate GNF at a time when land is not available for application, you must use a contingency process to properly manage the GNF. If this process is not available, you will not be able to generate GNF. This may cause plant damage and shutdown of your operation, which could result in severe financial impact.


NMAN is a software program developed by OMAFRA to help implement the nutrient management program. Consultants, farmers, greenhouse operators and other businesses can use the software to plan for non-agricultural source material, agricultural source material and GNF compliance, analyze options and print reports to demonstrate compliance.

We updated the NMAN software to include a worksheet to help individuals develop Greenhouse Nutrient Feedwater strategies and plans. Visit the NMAN web page for more information on these updates.

Training and education

The regulation prescribes a number of nutrient management practices. These practices include:

  • preparing GNF strategies, plans or land application schedules for an agricultural operation
  • engaging in the business of applying GNF to land at an agricultural operation subject to a GNF Plan
  • transporting GNF
  • land applying GNF at an agricultural operation

Before carrying out any of these practices, you must meet the applicable requirements and complete the appropriate training. There are different requirements depending on the practice you wish to do.

GNF training requirements (for the purposes of subsections 71(5) and 71(6) of the regulation)

For nutrient management consultants and people wanting to prepare GNF strategies, plans and land application schedules for agricultural operations they do not own, operate or work for:

For GNF generators and receivers, greenhouse controllers and farmers wanting to prepare GNF strategies, plans and land application schedules for operations they own, manage or work for:

  • No specific certification is required
  • Must complete online training to allow them to review the regulatory requirements and to submit documents to OMAFRA

For independent carriers and people wanting to transport GNF for and between operations they do not own, operate or work for:

  • No specific certification is required
  • Must complete online training to review the regulatory requirements for transporting GNF

For people who represent businesses that want to land apply GNF and/or complete Land Application Schedules for agricultural operations they do not own, operate or work for, and the operations are subject to a GNF Plan:

For operators of land application equipment wanting to land apply GNF for agricultural operations they do not own, operate or work for:

Training and educational materials for individuals or companies who are interested in carrying out the practices listed above are available from the University of Guelph Ridgetown Campus. Visit the University of Guelph Ridgetown Campus website for more information on GNF training and educational resources, and for other nutrient management courses and certification opportunities.

Best Management Practice booklets

OMAFRA has Best Management Practices booklets to help greenhouse operators do self-assessments for their water and fertilizer use.

The following booklets will be available in 2015:

  • Self-Assessment and Best Management Practices for Water and Fertilizer Use in Container Nursery Production is specifically for Ontario container nursery growers.
  • Self-Assessment and Best Management Practices for Water and Fertilizer Use in Floriculture Production provides direction for Ontario's greenhouse flower growers.


Watch our Best Management Practices videos on water treatment and recycling for greenhouses and container nurseries to learn how you can improve greenhouse environmental performance.

More information

For more information on the Greenhouse Nutrient Feedwater Regulation or registering your operation under the NMA, contact the Agricultural Information Centre at 1-877-424-1300 or

For more information about compliance with the GNF Regulation, the OWRA, the EPA, and other options for disposing of GNF, visit the MOECC Environmental approvals web page, or call 1-800-565-4923.

For more information:
Toll Free: 1-877-424-1300