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Sewage Biosolids: A Valuable Nutrient Source

Author: OMAFRA Staff
Creation Date: 18 September 2009
Last Reviewed: 18 September 2009

Table of Contents

Large photograph of a tractor pulling a drag-hose injection unit that is injecting liquid sewage biosolids directly into the soil. Sewage biosolids are pumped to the injection unit through a hose that is attached to the injection unit which is dragged along behind the unit as it passes over the field.

What are Sewage Biosolids?

Sewage biosolids are nutrient-rich materials that result from the treatment of municipal wastewater. They contain nitrogen, phosphorus and organic matter as well as essential micro-nutrients such as copper, iron, molybdenum and zinc, all of which are important for plant growth and soil fertility.

Land Application

Ontario has successfully regulated land application of sewage biosolids as a crop fertilizer since the early 1970's. Sewage biosolids applied to agricultural land must be treated by an approved process and they must be tested to determine nutrient content and to ensure they meet provincial quality standards. The land application site and receiving soils also must meet specified requirements and quality standards.

Side-by-side photographs showing mature corn and wheat crops in agricultural fields. Sewage biosolids are often used as a fertilizer on farms to grow corn and cereal crops such as wheat.

Sewage biosolids are often used as a fertilizer on farms to grow corn and cereal crops such as wheat.

Why Land Application?

Sewage biosolids are a valuable nutrient source for growing field crops such as corn, soybeans, canola and cereals. They are also highly suitable for growing forage crops and for improving pasture. Using sewage biosolids as a nutrient source for field or forage crops or for improved pasture:

  • Reduces the need for commercial fertilizers;
  • Reduces production costs;
  • Improves soil fertility;
  • Enhances soil structure, moisture retention and soil permeability;
  • Adds organic matter that helps to maintain good soil tilth and reduce the potential for soil erosion and runoff.

Recycling this valuable resource benefits farmers and society. Farmers receive a substantial economic benefit because sewage biosolids provide nitrogen, phosphorus and other micro-nutrients that farmers would otherwise have to purchase to grow their crops. As a fertilizer equivalent, the nitrogen and phosphorous in biosolids has a value of approximately $250/hectare. Also, recycling sewage biosolids to land is an environmentally desirable alternative to landfill disposal as it promotes waste diversion.

Land application of sewage biosolids is not typically used as a source of nutrients for fruit and vegetable crops. Under current legislation, waiting periods of up to 15 months are required before fruit and vegetable crops may be harvested after sewage biosolids are applied. Due to these restrictions, fruit and vegetable farmers use compost and other nutrient sources in their operations, rather than sewage biosolids.

There are also waiting periods for grazing livestock following the application of sewage biosolids. After the application of sewage biosolids, horses, beef and dairy cattle require a two month waiting period before grazing and swine, sheep and goats a six month waiting period is required.

Biosolids Utilization Committee logo

The Biosolids Utilization Committee (BUC) supports the land application of sewage biosolids in conjunction with a strong regulatory framework and best agricultural management practices.

Municipal Wastewater Treatment

Aerial view of a municipal wastewater treatment plant.

Aerial view of a municipal wastewater treatment plant.

Municipalities in Ontario currently operate more than 300 mechanical wastewater treatment plants which are designed to collect and treat wastewater from residences and commercial and industrial facilities. These plants separate the solids from the liquid portion of the wastewater. The solids then undergo biological treatment where micro-organisms break down the organic components into forms that are more stable. Biological treatment also greatly reduces the number of pathogen and other potentially harmful organisms in the material as well as the potential for odour. This biological break down process is similar to what happens in the natural environment.

The two main types of biological treatment to treat solids generated at municipal wastewater treatment plants are anaerobic digestion and aerobic digestion.

Schematic illustration of a typical wastewater treatment process.

Text Equivalent of Diagram

Illustration of a typical municipal wastewater treatment process involving anaerobic digestion to treat the solids removed from the wastewater. The sewage biosolids that result from this treatment may then be applied to agricultural land as a crop fertilizer if they meet provincial quality standards.

Regulatory Framework

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) works closely with the Ontario Ministry of the Environment (MOE) to administer Ontario's successful sewage biosolids land application program. The land application of sewage biosolids as a farm fertilizer will ultimately be governed by provisions set out under the General Regulation 267/03 under the Nutrient Management Act. This new framework will regulate all non-agricultural source material (NASM) that are applied to land to benefit the growing of agricultural crops such as food processing residuals, pulp and paper biosolids and municipal biosolids.

Land application of biosolids has been done in Ontario under a Certificate of Approval issued by the MOE. Under the new amending regulation, biosolids application on agricultural land will require an approved NASM plan instead of a Certificate of Approval. This new requirement takes effect January 1, 2011, or when a valid Certificate of Approval for a given site expires but no later than January 1, 2016.

The regulation under this Act and supporting publications (e.g. guidelines, protocols) outline the strict requirements and standards that must be met to use sewage biosolids as a nutrient source in an agricultural crop production system. The requirements and standards for using sewage biosolids ensure they are used properly and their use is protective of public and animal health, food quality and the environment.


The regulation and protocols under the Nutrient Management Act describe the standards and requirements that must be met to use sewage biosolids as a crop fertilizer.

Key requirements under the regulations include:

  • Government approval of the treatment processes;
  • Laboratory analysis of the sewage biosolids and receiving soils to ensure they meet quality standards;
  • Government approval of the fields that receive sewage biosolids, and the application methods;
  • Government certification and licensing of persons involved in NASM Plan preparation and land application;
  • Detailed record-keeping.

Ministry Roles

Under the new amending regulation MOE staff will continue to be responsible for required approvals under the Ontario Water Resources Act and the Environmental Protection Act, where appropriate. They will also continue to be responsible for compliance and enforcement of the provisions set out under those Acts as well as the Nutrient Management Act, 2002 (NMA). Together these pieces of legislation govern how sewage biosolids must be treated, transported and managed as a nutrient and utilized as a crop fertilizer. MOE staff also conduct regular inspections of the municipal wastewater treatment plants producing sewage biosolids.

OMAFRA staff will be responsible for all required approvals of the NASM Plans, certifications and licences under the NMA and O. Reg. 267/03. They are also responsible for the development and delivery of all training courses associated with those requirements. OMAFRA will also provide notification to municipalities when a NASM plan is approved.

Land Application Standards

Soil tests are required to ensure an agricultural field is suitable to receive sewage biosolids. The concentrations of phosphorous and metals in the soil, and the acidity or alkalinity (pH) of the soil must meet provincial standards.

Small photograph of a tractor pulling a drag-hose injection unit that is injecting liquid sewage biosolids directly into the soil.

Other site standards in the regulations include:

  • Lands that receive sewage biosolids must be a minimum distance away from residences, residential and commercial areas, municipal and private wells, and surface watercourses;
  • Surface slopes must not exceed specified limits;
  • Depth of soil to bedrock and groundwater must meet minimum requirements;
  • Timing, method and rate of application must be appropriate for the conditions at each site and the farmer's crop production system.

Small photograph of a special type of land of application equipment called a 'Terra-gator' which is similar to a small tanker truck with an injection unit attached at the rear. This equipment is self-propelled and has large floatation tires which help to minimize the risk of soil compaction from the weight of the equipment and sewage biosolids held in the tank. Sewage biosolids move from the tank to the injection unit where they are injected directly into the soil.

The application rate or the amount of sewage biosolids applied to an agricultural field is based on the soil test results for the field and crop nutrient requirements. However, regulations also limit the amount of heavy metals and solids that may be applied to the soil and these restrictions can influence the application rate.

Small photograph of a typical farm tractor pulling a four-wheeled liquid tank spreader which is similar to a liquid manure spreader. Sewage biosolids held in the tank move to a nozzle or splash plate at the rear of the tank where they are then sprayed under pressure on to the soil.

The methods used to apply sewage biosolids to land are similar to those for commercial fertilizers and manure. The most common methods are injection or surface application followed by incorporation into the soil. These methods are favoured by the BUC because they conserve nitrogen and phosphorus, reduce odours and minimize run-off. The photos at the side show liquid sewage biosolids being applied with common types of equipment used to apply liquid agricultural nutrients. The photos below show dewatered (solid) sewage biosolids being surface applied and then incorporated into the soil.

It is important for the municipal wastewater treatment plant, the land applicator and the farmer to be in regular contact to ensure that the timing and rate of application are appropriate and fit the farmer's overall crop management program. This co-operation ensures mutual satisfaction and also results in good land stewardship practices.

Record Keeping

Municipal wastewater treatment plants (under their C of A), land applicators and farmers are required to keep detailed records for all sites where sewage biosolids are applied to agricultural land. The records include:

Site location;

  • Soil test results for each field;
  • Laboratory analyses for the sewage biosolids;
  • Quantity of sewage biosolids applied to each field;
  • Application rate for each field.

Photograph of a person recording various types of information for a field that has received sewage biosolids. Records such as the amount of sewage biosolids applied and the date of application must be kept for each field that receives sewage biosolids.

Detailed records must be kept for each agricultural field that receives sewage biosolids.

The farmer needs this information to make appropriate nutrient management planning decisions. It must also be available to MOE staff during a site inspection.

Monitoring and Research

Since the early 1970's, MOE and OMAFRA, in partnership with federal and municipal governments, universities, the farming community and sewage biosolids industries and associations, have carried out or funded many monitoring and research studies to evaluate the benefits and assess the potential risks of using sewage biosolids as a nutrient source for growing agricultural crops. The knowledge and experience gained from these studies is used to ensure government regulations are current and to promote best management practices. Research will continue in the future to ensure the requirements and standards specified in the regulations continue to be effective.

This is another photograph of a typical farm tractor pulling a drag-hose injection unit that is injecting liquid sewage biosolids directly into the soil.

Field studies implemented by the two ministries and various partners also confirm that the application of sewage biosolids to agricultural land poses minimal risk to soil and crop quality. These findings are in agreement with those of other scientific studies conducted by researchers in the European Union, the United States, and other countries.

This is a side view of the equipment used to apply dewatered sewage biosolids on to an agricultural field. This photograph shows the sewage biosolids being flung out on to the field from a discharge chute that is located at the front of the box near the cab of the tractor about axle height from the surface of the field.

Beyond The Regulatory Requirements

Municipalities and companies involved in the land application of sewage biosolids continue to help make agricultural use a success by taking actions to improve or enhance the benefits and at the same time provide greater protection of public health and the environment. These actions include:

  • Implementing municipal sewer-use bylaws to reduce the amounts of contaminants that enter wastewater treatment plants;
  • Using improved sewage biosolids treatment processes;
  • Developing new land application technologies;
  • Adopting Environmental Management System operating procedures and best management
  • Placing greater emphasis on public communication.

This is another front view photograph of a typical farm tractor pulling a four-wheeled tank spreader that is spraying liquid sewage biosolids on to the field from a nozzle or splash plate at the back of the tank.

Photograph of new high-pressure equipment that is able to inject dewatered sewage biosolids directly into the soil. The equipment consists of a typical farm tractor and a separate, specially designed, open-topped box carried on four large floatation tires that help to minimize the risk of compaction. The high pressure injection unit is mounted on the back of the box. Dewatered sewage biosolids held in the box are hydraulically pushed to the rear of the box and into the high pressure injection unit which then injects the sewage biosolids into the soil.

New technology continues to improve how sewage biosolids are applied to land. High-pressure injection equipment can now inject dewatered sewage biosolids into the soil.

About The BUC

The BUC is a multi-stakeholder advisory committee to MOE and OMAFRA and is supported by staff of the Ministry of Health and Long-Term Care and non-government members from agricultural and industrial organizations, municipalities, service industries and the academic and scientific communities.

The role of the BUC is to advise the two ministries on matters related to the use of municipal, commercial and industrial by-products in agricultural and non-agricultural land use activities.

BUC Membership*

  • Ontario Ministry of Agriculture, Food and Rural Affairs
  • Ontario Ministry of the Environment
  • Ontario Ministry of Health and Long-Term Care
  • Agricultural Groups Concerned about Resources and the Environment
  • American Water Canada Corporation
  • Association of Local Public Health Agencies
  • Ontario Association of Sewage Industry Services
  • Ontario Clean Water Agency
  • Ontario Federation of Agriculture
  • Ontario Forest Industries Association
  • Ontario Soil and Crop Improvement Association
  • Rural Ontario Municipal Association
  • University of Guelph
  • Water Environment Association of Ontario

*Standing member organizations. Other organizations and individuals with scientific knowledge and expertise also participate as members from time to time.

Want More Information?

To learn more about sewage biosolids and its use as a nutrient source in agriculture visit these web sites:

To obtain more detailed information on the use of sewage biosolids as a crop fertilizer, go to:

"Fertilizing with Biosolids" published by Oregon State University

To get a copy of the regulation and protocols under the Nutrient Management Act, go to:

Nutrient Management Regulation and Protocols

To learn more about the BUC or if you have a question concerning the use of sewage biosolids as a crop fertilizer in Ontario, contact:

The Agricultural Information Contact Centre of the Ministry of Agriculture, Food and Rural Affairs
1-877-424-1300, E-mail: ag.info.omafra@ontario.ca. Northern Ontario Regional Office: 1-800-461-6132, Website: www.ontario.ca/omafra

Illustrations and photographs courtesy of the Ontario Ministry of Agriculture, Food and Rural Affairs.

Learn More

Non-Agricultural Source Material (NASM) - information on new regulatory requirements.


For more information:
Toll Free: 1-877-424-1300
Local: (519) 826-4047
E-mail: ag.info.omafra@ontario.ca