A geographical profile of livestock manure production in Canada, 2006
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Nancy Hofmann, Environment Accounts and Statistics Division
Manure1 is a by-product of raising livestock and is a source of many valuable crop nutrients. Nitrogen and phosphorus, in particular, are important nutrients for crop production. Manure is also a source of organic matter, which can help reduce soil erosion and improve soil's water-holding capacity.
Although manure provides many benefits, it can also become a source of pollution with impacts on the environment and human health. For instance, bacteria found in manure have been found both in municipal and private drinking water supplies.2 Manure can also be a source of nuisance odour (see textbox "Controlling odour.")
This article profiles manure production in Canada. Linking manure production to environmental quality is beyond the scope of this study—many other factors such as soil type, climate, precipitation, topography and manure management practices would also need to be included in assessments of environmental issues such as water quality.
From 1981 to 2006, total manure production in Canada rose 16%. The intensity of manure production—the amount produced within a given area—rose in about half of the sub-sub-drainage areas (SSDA) studied (see textbox "What you should know about this study" for more information on the SSDA framework).
This study uses livestock data from the Census of Agriculture. The data reflect the number of livestock on farms on Census day, May 16, 2006, assuming constant livestock numbers throughout the year, though in actual fact these numbers do fluctuate.
The study included beef cows, heifers, milk cows, bulls, steers, calves, horses, sheep, lambs, goats, grower/finishing pigs, nursing/weaner pigs, sows, boars, steers, broilers/roasters, laying hens, pullets and turkeys. Other livestock in Canada , such as buffalo, deer, and rabbits, were not included in this analysis because their overall contribution to total manure produced is small and agreement on manure production coefficients has not been reached.
Livestock numbers were multiplied by coefficients estimating daily manure production per animal. Agriculture and Agri-Food Canada (AAFC), academics, consultants and non-governmental agencies were consulted in the development of these coefficients. The coefficients used are listed in: www.statcan.ca/english/research/21-601-MIE/21-601-MIE2006077.pdf . Estimates of manure production tabulated by AAFC in the National Land and Water Information Systems are slightly different as a result of rounding of the coefficients.
Census livestock data were allocated to drainage areas in accordance with procedures developed by AAFC in collaboration with Statistics Canada's Agriculture Division. Please see: Definitions, Data sources and methods, 8012, Census of Agriculture: Environmental Geography Aggregations of Census Farm Units or Agriculture and Agri-Food Canada, 2008, Interpolated Census of Agriculture to Soil Landscapes, Ecological Frameworks and Drainage Areas of Canada.
Estimates of manure production are normalized by sub-sub-drainage area (SSDA) land area to permit comparison of manure production totals across drainage areas of different sizes. The resulting manure production intensity estimates, in kilograms per hectare, provide measurements that are comparable across different regions and time. This indicator of manure production intensity has been previously produced for 1996 and 2001, with comparisons made to 1981. Biophysical landscape units such as drainage areas, eco-regions and soil landscape are relevant to assess agri-environmental indicators such as manure production intensity.
Manure production can have impacts not only at the farm level, but may also have an effect in other areas of the same basin, whether that area is used for agriculture, urban or other uses. Moreover, the small size of the SSDA provides valuable localized information, which is a valuable asset for nutrient-balance analysis at the watershed level.
Drainage area framework
The SSDA is the smallest unit in the National Hydrological Network of Canada. Drainage areas, also called watersheds or drainage basins, are areas where all contributing surface waters share the same drainage outlet. In 2006, livestock were found in just under 400 of these SSDAs.
One limitation of the analysis is that the application of manure can be more intensive in some SSDAs than others due to the amount of appropriate farmland available. Manure application can be done mechanically or naturally, by livestock while grazing. As well, not all manure is necessarily applied in the SSDA where it was produced—it can be exported to neighbouring SSDAs.
Farm-generated odour, particularly from manure, is a frequent source of conflict between farmers and their non-farming neighbours. In Ontario, odour is the cause of more than half of the agricultural complaints received by government and the number of complaints is increasing. Common compounds associated with livestock manure include hydrogen sulphide and ammonia. These compounds are more common in manure from hogs and poultry.
One means of reducing these complaints is by providing adequate distances between livestock facilities and non-farm uses. Various factors influence the actual separation distance including the size and type of livestock operation. In Ontario, for instance, regulatory minimums require that an operation with 1,800 hog per year and a covered manure system would have a separation distance of about 650 metres between its barn and residential or institutional zoned areas. In contrast, a dairy farm with 60 milking cows and an open liquid tank would have a separation distance of 394 metres.
Source(s): Ontario Ministry of Agriculture, Food and Rural Affairs, 2003, Odour Control on Livestock and Poultry Farms. Factsheet no. 03-111, (accessed September 23, 2008 ).
In 2006, Canadian livestock produced about half a million tonnes of manure daily. This translated to over 180 million tonnes over the year. Of this total, 38% was produced by beef cows, followed by milk cows (12%), calves (12%), heifers (12%), steers (10%), pigs (9%), poultry (3%), horses (2%), bulls (2%) and sheep (less than 1%).
How much manure does each animal produce?
Generally all types of cattle produce large amounts of manure: bulls (42 kg/day), beef cows (37 kg/day), steers (26 kg/day), heifers (24 kg/day) and calves (12 kg/day). Milk cows produce the most manure at 62 kg per day, which is about 10% of the weight of an average cow.
In contrast, the different categories of pigs including weaners, sows, boars and market hogs produce much smaller amounts of manure, between 1 and 4 kg per day.
Of all livestock types examined, poultry produce the least amount of manure, with each bird producing less than 1 kg of manure per day.
Manure production increased by 16%, or by an estimated 25 million tonnes from 1981 to 2006, largely as a result of increasing number of beef cows on farms. The amount of manure generated by beef cows grew by 44% or 21 million tonnes between 1981 and 2006 (Table 1).
Manure production also increased for other types of livestock as a result of increases in the number of animals. Manure production from heifers rose 9 million tonnes, production from calves rose 5.5 million tonnes and total pig manure rose 5 million tonnes. These increases in manure production were offset by declines in manure from other livestock types, particularly milking cows which experienced a decline of 44% or 18 million tonnes of manure. Productivity improvements allow each milk cow to produce more milk, allowing farmers to reduce the number of milk cows while retaining milk production levels.
Manure production was concentrated in three major clusters in 2006 (Map 1). These clusters are located in central and southern Alberta, south-western Ontario, and south-eastern Quebec. There were smaller clusters of high production in southern Manitoba, southern British Columbia and Prince Edward Island. Average manure production across all SSDAs with livestock was about 1,070 kilograms of manure per hectare of land (kg/ha).
Cattle produced most of the manure in the top manure-producing SSDAs in Alberta , whereas manure was produced by a wide range of livestock including poultry, cattle, milk cows and pigs in the top producing SSDAs in southern Ontario and Quebec. Pigs dominated manure production in southern Manitoba.
Overall, manure production intensity went up in half of SSDAs with livestock from 1981 to 2006, while the other half experienced a decline in manure production per hectare.
Livestock in Ontario's Maitland SSDA, located east of Lake Huron, produced the most manure per hectare of land, with 8,950 kg/ha (Chart 1). The Upper Thames and Upper Grand, also in Ontario, were the second and third most intensive manure-producing SSDAs respectively.
Ontario prominent among the ten most intensive manure-producing sub-sub-drainage areas in 2006
Ontario was home to several of the most intensive manure-producing SSDAs. For instance, of the five SSDAs across the country with manure production levels over 6,000 kg/ha, four were located in Ontario.
The SSDAs with the largest increases in manure production per hectare between 1981 and 2006 were predominantly found in Alberta. The Little Bow SSDA experienced the largest increase, at about 3,350 kg/ha (from 1750 kg/ha in 1981 to 5100 kg/ha in 2006). Overall, eight SSDAs in Alberta were among the ten SSDAs with the largest increases in manure production intensity (Chart 2).
Sub-sub-drainage areas in Alberta experienced the greatest increase in manure production per hectare, 1981 to 2006
These increases in Alberta were mostly a result of the rise in cattle numbers. In the Little Bow, for instance, 30% of the increase in manure production was due to the increase in steers—and they represent just one type of cattle. Increases in southern Manitoba were the result of larger numbers of pigs.
- For the purposes of this article, manure consists of livestock feces and urine.
- Government of Saskatchewan, 2007, Illnesses from Water and Food, (accessed September 26, 2006).