Production of nitrogen and phosphorus from livestock manure, 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 nutrients including nitrogen and phosphorus. However, these nutrients can also become a source of pollution, resulting in water contamination and unwanted air emissions.2 For instance, an overabundance of nutrients can foster excessive plant and algae growth in water bodies. When these plants die, their decomposition removes dissolved oxygen from the water, making it unsuitable for fish and other forms of aquatic life, a process known as eutrophication.
This article is a follow-up to "A geographical profile of livestock manure production in Canada, 2006" published in the December 2008 issue of EnviroStats. Please refer to the earlier article for information about the methodology, definitions and data sources used here.3
In 2006, Canadian livestock manure contained 1.1 million tonnes of nitrogen and 300 thousand tonnes of phosphorus, up by 17% and 21% respectively from 1981 levels. These increases are a result of increased populations of livestock as well as variations in nutrient output by animal type.
Nitrogen and phosphorus production from livestock manure were concentrated in the same general clusters as those for overall manure production reported in the earlier article. These nutrient clusters were located in central and southern Alberta, south-western Ontario, and south-eastern Quebec (Maps 1 and 2). There were smaller clusters of sub-sub drainage areas (SSDAs)4 with high nutrient production in southern Manitoba and southern British Columbia.
Manure contains varying amounts of organic matter, water and nutrients, but generally includes more nitrogen than it does phosphorus. Larger animals, such as cattle, produce more manure, and thus generate greater amounts of nutrients. However, there are other differences due to livestock type. For example, pig and poultry manure contains relatively more phosphorus than other types of manure.5
Overall, beef cows produced the most nitrogen, followed by calves, heifers, milk cows and pigs (Table 1). Pigs produced a greater share of total phosphorus than nitrogen; they generated the second highest amount of phosphorus behind beef cows. Most manure in Alberta was produced by cattle, whereas manure was produced by a wider range of livestock in southern Ontario and Quebec.
Table 2 lists the top ten nitrogen- and phosphorus-producing SSDAs in Canada. These ten SSDAs were responsible for 17% of the total nitrogen and also total phosphorus produced in livestock manure in 2006. SSDAs in Alberta and Ontario dominated the top ten rankings for total nitrogen and phosphorus production by weight.
However, when manure production is divided by the size of the drainage area to obtain a measure of intensity, in kilograms of manure per hectare, SSDAs in Ontario out rank basins from other provinces (Table 3). Sub-sub-drainage areas vary in size, with basins found in southern Ontario and Quebec often much smaller than those found elsewhere in the country. For instance, the Maitland SSDA occupies an area of about 260,000 hectares, about one third the size of the Little Bow SSDA which covers an area of almost 800,000 hectares.
- For the purposes of this study, manure consists of livestock feces and urine.
- For more information on the impacts of nutrients on the environment please visit Nutrients and their Impact on the Canadian Environmentby Environment Canada.
- To summarize, census livestock data were allocated to drainage areas in accordance with procedures developed by Agriculture and Agri-food Canada 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.
- 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.
- K. Buckley and M. Makortoff, 2004, Phosphorus in Livestock Manures, (accessed November 27, 2008).