Making Manure Processing
a “Standard Practice”

Bruce T. Bowman, Former Chair
Expert Committee on Manure Management
Canadian Agri-Food Research Council

Oct. 29, 2003  [updated Feb. 19, 2004]

The purpose of this document is to stimulate discussion on this important issue.

Ideas and opinions expressed in this document are those of the author and do not represent the official position or policies of any organization.




Confined livestock production in Canada is approaching a critical crossroad in the next few years, which will determine how viable its future is in this country. Globalization of agriculture is continually pushing livestock farmers towards expansion of their operations in order to remain competitive, while they seem to face unending crises, whether it be BSE, Walkerton-type water crises, or climate extremes, each of which threaten their economic survival. For the most part, issues discussed in this document do not apply to the less-intense, grazing-based livestock systems.

In Quebec, intensification of the hog production industry has led to severe overloading of nutrients, especially phosphorus, in both surface and groundwater aquifers, while creating unacceptable odour problems for nearby rural neighbours. This has led to rather draconian measures to restrict further livestock development until health and water quality concerns can be adequately addressed. In Ontario, the continuing exodus of urban populations into rural areas is continuing to reduce available space for livestock operations to exist, as determined by Minimum Separation Distance regulations. To compound this issue, there are increasing instances of rural neighbours (who may also be farmers) no longer feeling safe being in close proximity to large livestock operations. Public pressure on municipal governments is leading to more stringent siting restrictions for these operations, and there are increasing incidents of vigilante actions threatening proponents of new or expanding livestock operations. Even on the prairies, where there appears to be adequate space for livestock expansion, there have been protests from rural neighbours not feeling safe near these large operations (Steinbach, Manitoba).

From an economic perspective, confined livestock production behaves in a similar fashion to other industries such as electronics, or automobile manufacturing, and will migrate to regions of the world having lower labour costs, and more lax environmental restrictions on operations. Already vertically-integrated livestock production giants, such as Smithfield Foods (USA), have started operations in Eastern Europe (Poland), and will probably move on eastward into the Ukraine and Russia as labour costs and environmental restrictions increase in Poland in coming years. Similar scenarios probably exist in parts of South America, which will siphon livestock operations from North America, as increasing domestic restrictions are brought to bear on the industry.

If Canada is to keep a viable and competitive livestock production industry flourishing here in the coming decades, it is imperative that solutions be soon found to allow confined livestock production to safely co-exist in reasonable proximity to their rural neighbours, while conserving and protecting our irreplaceable natural resources (soil, air, water, human health and safety).

When considering sustainable agricultural production, it is essential that an appropriate balance be established amongst three primary factors, which are:
  1. Productivity (Yield/Economics/Profits),
  2. Environmental Protection, and
  3. Societal Values.

To visualize the interaction between these factors, different farm operations could be positioned inside a virtual cube, having the above factors as the primary axes. 

Sustainable nutrient management - balancing productivity, environment and societal issues: comparing two differently managed farms, F1, F2

Whereas both productivity and environmental protection are usually science-based, societal issues are often perception-based, and can quickly overrule either science or logic, and is often expressed with a NIMBY (not in my back yard) attitude. Once this process of fear and distrust by the public has taken root, it becomes increasingly difficult to stop or reverse the process, with the result that the producer is often the looser.

Compounding the entire issue is the fact that agriculture production has become so highly efficient over the past several decades that less than 2% of our population are now involved in primary agriculture production. Agriculture is becoming a “non-visible minority” in an increasingly urban-focussed consumer world. Consumers are often so disconnected from their food sources that they don’t realize, nor even care that farmers are important to their well being, since they all know that their food comes from supermarkets!! It doesn’t matter to many consumers where their food comes from until they get sick from a contaminated source, such as the incident of imported strawberries carrying pathogens from South America several years ago. Currently, Canada does not have a mandatory food tracking system. Without the recognition, understanding, and support of the urban population for the importance of high quality, domestically-produced agriculture produce over which we have some control for quality and safety, farmers are in great jeopardy for their long-term survival in a global marketplace, based primarily on price. 

One significant consequence of agricultural intensification and specialization in the post-World War II era has been the separation of cereal crop production from livestock production in North America. This has resulted in wide spread nutrient excesses within livestock production systems, and even more so throughout the human food supply system. While cheap mineral fertilizers have not made it economic to recycle excess livestock nutrients back to cash crop production, lingering odours and pathogens associated with untreated manures have also hindered significant off-farm export of excess nutrients. However, there are increasing negative environmental impacts associated with both nitrogen and phosphorus fertilizer production that will start to favour livestock nutrient recycling. Phosphate deposits are, in fact, finite (American phosphate reserves, <25 yr; remainder of more expensive reserves, before end of this century - Roberts & Stewart, 2002), and there are increasing environmental restrictions associated with mining them, while increasing energy costs and greenhouse gas emissions associated with urea production for commercial nitrogen fertilizers will increase their costs. See related article:  “Sustainable Nutrient Management in Agriculture and Closing the Loop on Large-Scale Nutrient Flows” .

"Renewable Energy" is an emerging issue that is also starting to impact on livestock production issues as well. As governments develop programs to reduce our dependence on traditional fossil fuels, which in turn reduce their environmental footprint, there is a realization that renewable forms of energy, such as wind, solar and biomass can play a vital role. One type of biomass energy comes from farm-based sources such as livestock wastes (manure, deadstock, etc). Farm-based renewable energy can make a positive contribution to a national renewable energy strategy by providing distributed, baseload capacity (7/24 operation), while remediating important environmental problems (odours, pathogens, ghg emissions). Farm-based renewable energy programs are well advanced in several parts of the European Union, as well as in several of the States in the U.S.A., and with similar development in Canada could improve the economics for manure processing, which in turn has positive benefits outlined in this paper.

In summary, there are two major issues that need to be addressed, both related to the need to reduce odours and eliminate pathogens from manure:

  1. Need for livestock producers to regain public trust in their farming operations,
  2. Need to export (recycle) excess nutrients (N, P, K) from livestock farms.


Steps Toward a Sustainable Solution

1. Setting a New Goal

The first important step towards solving this impending crisis for livestock production in Canada would be to establish a long-term goal of “adopting manure processing as a Standard Practice” for confined livestock operations. In this context, “manure processing” implies that the entire manure volume (wet or dry) should be processed to substantially reduce odours and eliminate pathogens, preferably employing closed or contained systems to also conserve nutrients. There are at least two important conditions that need to be linked to this goal:

  1. Adoption by livestock producers should be a gradual process over the next decade or more, which should be promoted through demonstration of the practices.
  2. Adoption should be achieved primarily though policy changes to foster better practices, with regulations acting as a safety net (performance baseline). Farmers respond more positively to incentives (particularly economic) than to regulations.

Key issues that must be addressed in this context include the following:

  1. Manures must be processed to substantially reduce odour and eliminate pathogens as health and safety issues, which will begin the process of restoring public trust in livestock operations, and allowing them to peacefully co-exist with rural neighbours.
  2. Odour emissions are frequently a major issue before the storage and processing stages - in the confined housing of livestock and in the practices used to collect and transfer manure. Initiatives need to be focussed on housing system designs that reduce odour production, and to collection systems that strive to remove manure while still fresh, before it starts generating substantial odours. An additional benefit to rapid collection and processing is the conservation of volatile ammonia, much of which is lost before the manure even reaches the storage/processing stage.
  3. Farmers will require greater flexibility in managing excess nutrients in livestock manures, as a result of increasingly stringent nutrient management regulations. Once the manure is essentially odour and pathogen-free, and the processed manure is in an air-dry state, excess nutrients can be economically exported from the farm in the form of value-added amendments.  In a whole farm nutrient balance study of 33 Nebraska confined livestock operations, Koelsch & Lesoing (1999) found that 75% and 50% of the farms had significant N & P imbalances, respectively (50% more nutrient inputs than outputs). Further insight into farm-scale nutrient flows and balances is presented in a small watershed-scale study by Nord and Lanyon (2003).
    This has some very important implications for the large-scale re-distribution of excess livestock nutrients, as organic amendments, back to cash crop production, now relying solely on annual mineral fertilizer inputs which, in the longer term, is not sustainable. Organic amendments provide soil quality improvements in addition to the nutrient value, which mineral fertilizers can not provide.


2. Making Manure Processing Profitable

The key to making manure processing a “Standard Practice” for confined livestock operations is making it profitable or, at least in the beginning, more affordable.

Unfortunately, there appears to be sparse information in the literature quantifying the value of manure treatment to farmers based on societal impacts and benefits. However, we know that persisting odour and pathogen issues from failure to process manure, or to control odour emissions from the housing facilities, can create real obstacles for rural neighbours, who through their municipal governments, can make it increasingly difficult and costly for producers to expand or even renew their existing operations, and thus remain in business. In this context, manure processing does have a “real incentive value” for the farmer, although it is manifested not in direct profits, but rather as a “societal approval” to continue in business.

Once farmers can profit by processing their manures, most of the environmental problems associated with manure management will diminish because nutrients become valuable and farmers will quickly exceed current environmental nutrient management regulations to create more profits. In essence, the regulations will become a safety net, or performance baseline for the farmer.  See more detailed discussion of factors influencing manure management: “Changing the paradigm for manure management”:

There are two basic approaches for complete processing of livestock manures -composting, and anaerobic digestion.

A. Anaerobic Digestion (AD)

In the early stages of adopting manure processing as a standard practice, larger confined livestock operations with liquid manure systems which have nutrient excesses to export and/or, which are able to produce green energy (electricity and heat from anaerobically-generated biogas), will benefit the most. In this case, revenue streams from both exported green electricity and value-added soil amendments have the potential to produce positive cash flows and complete payback of investment within a few years. Although total numbers of large operations able to take advantage of this technology may currently be rather limited, this class of livestock operation accounts for a significant fraction of the total production from this sector, and adoption of this technology should have a positive environmental impact. Furthermore, this scale of operation is the best venue for initially demonstrating the technology. Innovation will help adapt the technology to smaller operations, once producer interest and acceptance starts to grow.

At a time when our electrical generating facilities across the country are being challenged to have a smaller environmental footprint, and to be more distributed and more diverse in their nature, farm-based generation of “green energy” can become an important contributor to this strategy. Some estimates place the potential for the generation of green electricity from agricultural organic wastes at 1,500 MW for Canada, and 250 MW for Ontario. Farm-based electricity generation, unlike other renewable sources such as wind and solar, are continuous 7/24 operations, which after a major power blackout (such as Aug. 2003 in eastern North America), can be back on line almost immediately, and also have the advantage of being distributed throughout the country-side, thereby reducing distribution losses. Farm-based systems could also take advantage of peak power demands and store biogas for increased generation during these periods.

Since AD systems are closed during the processing of the manure, all nutrients are conserved, including nitrogen (ammonia, ammonium), and methane is captured rather than being released to the environment. Consequently, the processed manure should retain a greater nitrogen content, while greenhouse gas (ghg) emissions during and following the processing should be lessened. Therefore, AD-processed manures should have a more favourable N:P ratio for plant growth than conventionally-handled liquid manures. The digestion process converts 50% or more of the labile carbon in the manure to methane, and thus the resulting product is lower in carbon and less likely to cause nitrous oxide emissions when the treated slurry is land applied ( Barton & Schipper, 2001).  In addition the nutrients in the digestate will be in a more available mineral form and their release for plant growth will be more predictable.

The avoidance of ghg emissions during anaerobic digestion and subsequent co-generation of renewable energy may create a market for emission credits, which also could add to the profitability of the technology for the producer.

B. Composting

For confined livestock operations using solid manure handling, composting is the best means of processing the manures, which then can be exported as value-added products, if in excess of on-farm requirements for crop production. In situations where the farm operation collects significant volumes of nutrient-rich runoff water from the facilities, it may prove more profitable in the longer term to blend the solids to an optimum 10-12% content and anaerobically digest them to obtain biogas as well as value-added dried amendments.

While composting has a significant economic and technology advantage over AD systems through the simplicity of the practice (level of management required), and the much lower startup costs, revenues from composting would primarily be generated from exporting value-added products. However, many farmers have long recognized the value of “stabilizing” their manures by composting, even if the composted product is used only on their own property.

Provided that greenhouse gas emissions are minimized during composting by keeping the piles aerobic, the greatest disadvantage in composting is the considerable loss of ammonia-nitrogen during the process. Newer rotary composting systems employing controlled air flow may have potential to reduce ammonia losses to some extent. Consideration should also be given to lowering the pH of the moisture in composting manures to near neutrality, so as to maximize the ammonium (non-volatile) content and minimize the ammonia content. Like anaerobic digestion, the resulting product is essentially odour and pathogen-free, and greatly reduces the level of viable weed seeds in the composted products.

3. Developing Enabling Policies

There are several key policy changes that would trigger major changes in how confined livestock producers approach manure management:

A.  Providing access to electrical Grids - Net Metering

Perhaps the most significant key to changing the economics for farm-based co-generation digester systems would be for governments to mandate two things:

  1. Net Metering - give farm-based renewable energy access to electrical grids and,
  2. A Fair Market Price be paid for farm-generated electricity. 

This now provides another stable source of revenue for livestock producers.  In fact this can become a new constant revenue stream, an important step towards stabilizing chronically-depressed farm incomes, since livestock will continue to generate manure regardless of what farm commodity prices are!

Since farm-based energy systems can operate 7/24, they make an important contribution to "distributed baseload capacity" for the electrical grid, complimenting less-reliable wind and solar power sources.  Electrical transmission losses are typically in the 5-7% range, and having the generating capacity distributed across the countryside increases overall grid stability, while reducing transmission losses.

Farm-generated biogas can also be temporarily stored so that generation can be ramped up during peak demand periods (morning and evening).  This allows the farmer to maximize his revenue during peak demand, when generation costs routinely exceed 10 ¢/kwh, and sometimes peak above 15 ¢/kwh for short periods.  For the remainder of the day, the co-gen units can run at partial load, supplying the local needs of the farm operation.

Interestingly, the Ontario Ministry of Energy made a press release (Jan 20, 2004), expressing  the need for 300 MW of renewable energy.  It is estimated that in Ontario, livestock-sourced renewable energy could supply upwards of 200 MW, and across Canada, upwards of 1500 MW.

In Europe, Germany legislated a net metering law that provides a fair market price for renewable energy, and this has stimulated substantial growth in farm-based renewable energy. Similar net metering laws are now being implemented in several of the US States, including Vermont and Wisconsin.

B. Incentives for Livestock Nutrient Recycling/Re-Distribution

In order to reduce existing levels of agricultural sources of nitrogen and phosphorus in the environment, it is essential that policies be developed to promote the large-scale re-distribution and utilization of existing, excess livestock nutrients (as well as agriculture-sourced nutrients in the human food chain), as a partial replacement for new mineral fertilizers. A necessary prerequisite for off-farm export of excess nutrients is that the manure be odour- and pathogen-free and in an air-dry state - thus the need for manure processing.

Steadily increasing costs for producing commercial nitrogen fertilizers (urea) and mining the finite sources of phosphate fertilizers (25-yr supply, Roberts & Stewart, 2002) will make livestock nutrient recycling more attractive to cash crop producers, but additional policy changes are also required. Examples of this might be environmental taxes applied to commercial mineral fertilizer sources (N, P), or transportation assistance for recycled livestock nutrients. A first step in developing new policies is a comprehensive economic assessment of current practices and packaging technologies for processed manure, and to identify barriers to re-distribution and use of livestock nutrients.

C. Providing Environmental Loan Guarantees for Large Capital Investments

To facilitate adoption of these advanced technologies, it is essential that governments provide environmental loan guarantees to assist farmers in underwriting the risks associated with the design, installation and startup of manure processing systems. Such policies are appropriate in situations where there are significant co-benefits to the public as well as to the private (farmers) sector. Even when producers are prepared to adopt advanced manure processing technologies and have secured contracts for renewable energy sales and off-farm sales of value-added manures, there is frequently a huge obstacle in the way - up-front financing of the expensive equipment. If there is no default on the loans, there is no actual cost to the tax payer to underwrite these risks.

D. Incentives for Reducing Greenhouse Gas emissions and Emission Trading Credits

With the challenging targets that Canada has set for meeting its Kyoto commitments on greenhouse gas emission reductions, agriculture has a major role to play in reducing methane and nitrous oxide emissions. Rapid collection of fresh manure and processing it in closed co-generation AD systems is the most effective approach for conserving nutrients (especially nitrogen) while minimizing ghg emissions. Incentives need to be implemented to encourage these practices. At the present time an emission trading system is starting to develop in North America, which may provide additional revenues to livestock producers that can demonstrate significant avoidance of ghg emissions during the storage, processing and land application of their manures.



There are several key steps that need to be implemented to assist the confined livestock industry in solving some major environmental problems, becoming valued neighbours again, and maintaining a viable business operation. This will require a close working partnership between producers and governments to accomplish these goals,which are:

  1. Set a goal of making Manure Processing a Standard Practice.
  2. Implement net metering legislation for farm-generated electricity that would ensure both access to the grid and fair market value for the supplied electricity. Importantly, farm-based renewable energy systems can play a positive role in a national renewable energy strategy, specifically in terms of distributed energy production (reduced transmission losses) as well as providing consistent baseload capacity (7/24 operation), which neither solar nor wind sources can provide.
  3. Implement incentives for large-scale nutrient re-distribution back to cash cropping operations.
  4. Implement environmental loan guarantees for assisting producers to install advanced manure processing systems that reduce odour emissions, eliminate pathogens, and which substantially reduce ghg emissions.
  5. Establish ongoing communications with rural neighbours to keep them informed and to deal with issues before they become serious barriers to continued operation.


Related Reading

Regulation of Nitrous Oxide Emissions from Soils Irrigated with Dairy Farm Effluent (2001), L. Barton and L. A. Schipper. J. of Environmental Quality 30:1881-1887 (2001)

Interesting series of papers on Sustainable Farming by Dr. John Ikerd, Prof. Emeritus, U. of MissouriComplete set of Papers  (approx. 65) [3572 KB pdf].

Nutrient Balance on Nebraska Livestock Confinement Systems. (1999). Rick Koelsch, and Gary Lesoing. American Society of Animal Science and American Dairy Science Association.

Equal Access For American Farm Digester Electricity. Mark Moser, Resource Conservation Management, Inc. (RCM Digesters, Inc.) 

Managing Material Transfer and Nutrient Flow in an Agricultural Watershed (2003). E. A. Nord and L. E. Lanyon.  J. Environ. Qual. 32:562–570.

Inorganic Phosphorus and Potassium Production and Reserves. (2002) [98 KB pdf].  T. L . Roberts and W. M . Stewart. Better Crops. Vol. 86 (2002, No. 2)




Bruce T. Bowman, Archivist
Last Updated: Saturday, October 06, 2018 03:45:27 PM