Ammonia emissions from livestock industries in Canada: Feasibility of abatement strategies

Environmental Pollution 158 (2010) 2618e2626

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Ammonia emissions from livestock industries in Canada: Feasibility of abatement strategies Richard Carew Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97, P.O. Box 5000, Summerland, British Columbia, Canada VOH1Z0

Livestock NH3 emissions are higher in areas characterized by intensive livestock production with diet manipulation and land spreading offering the greatest potential for NH3 abatement options.

a r t i c l e i n f o

a b s t r a c t

Article history: Received 14 September 2009 Received in revised form 22 January 2010 Accepted 4 May 2010

An updated national ammonia (NH3) emissions inventory was employed to study the relationship between NH3 emissions and livestock industries in Canada. Emissions from animal agriculture accounted for 322 kilotonnes (kt) or 64% of Canadian NH3 emissions in 2002. Cattle and swine accounted for the bulk of livestock emissions. The provinces of Alberta, Ontario, Quebec, and Saskatchewan accounted for 28.1%, 22.0%, 18.7%, and 13.1% of total livestock emissions, respectively. Emissions from Ontario and Quebec were attributed to the intensive production of dairy, hogs and poultry. Dairy cattle emissions per hectolitre of milk were higher in Ontario and Québec than in other provinces, while swine emissions per livestock unit were higher than either beef or dairy cattle. A review of the abatement literature indicated diet manipulation to improve N efficiency and land spreading methods are very effective techniques to lower NH3 emissions. Future research is required to evaluate the feasibility of biofilters and feces/urine separation methods. Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved.

Keywords: NH3 emissions Livestock Abatement strategies Canada

1. Introduction Ammonia (NH3) emissions resulting primarily from livestock production have contributed significantly to the formation of fine particulate matter (PM2.5) which is recognized to have an adverse effect on human respiratory and cardiovascular health (Lillyman et al. 2009). The increased geographical concentration of Canadian livestock has resulted in nutrients available from livestock manure exceeding crop requirements in regions of Canada, and consequently causing negative environmental effects to the environment (Smith et al., 2006). Associated with increased specialization of livestock is increased concentration of waste byproducts, particularly NH3 emissions which contribute not only to fine PM2.5 formation, but also acidification and eutrophication of soils (Brink et al., 2001). Between the period 1990e92 and 2001e03, Canada’s agriculture NH3 emissions increased by 14 kt or 3%, attributed mainly to increases in livestock numbers and to a lesser extent greater fertilizer use (OECD, 2008). In 2002, Canadian NH3 emissions totaled 504.7 kt: animal agriculture, fertilizer and pesticides, industrial, and transport accounted for 64.0%, 22%, 6.5%, and 3.7%, respectively (Ayres et al., 2008a); beef, dairy, swine and poultry accounted, respectively, for 53.1%, 16.9%, 23.8%, and 6.2% of total

E-mail address: [email protected] (R. Carew).

livestock emissions; and Alberta, Ontario, Quebec, and Saskatchewan accounted for 28.1%, 22.0%, 18.7%, and 13.1%, respectively. Between 2001 and 2006, Canada’s beef herd population expanded in most provinces with the exception of British Columbia (BC), Alberta, and Nova Scotia, whereas swine numbers increased in the Prairie Provinces as well as in Ontario (Agriculture and AgriFood Canada, 2008a). This expansion in livestock numbers increased beef and pork meat production since the early 1990s. In 2008, Canada’s annual production of beef, pork and poultry was 1288, 1941 and 1221 kt, respectively, an increase of 47, 66 and 64% compared to the early 1990s (Fig. 1a). Canadians have decreased their consumption of beef and pork but increased their consumption of poultry meat (Fig. 1b). In 2008, beef and pork per capita consumption was 12.8 and 9.7 kg, respectively, a decrease of 14 and 18% compared to the early 1990s. Poultry meat per capita consumption was higher than either beef or and pork and totaled 13.6 kg in 2008, a 23% increase from the early 1990s (Fig. 1b). To meet expanded beef, pork and poultry production for domestic consumption and exports has led to intensive livestock production and increase NH3 emissions. The bulk of NH3 released from farms comes from livestock urine, animal manures, ammonium-based fertilizer and crop residues (Agriculture and Agri-Food Canada, 2008b). The most important factors affecting NH3 volatilization include ammonium concentration, pH, and exposure to the atmosphere. In response to intensive

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Sommer (2003) was employed to develop the agricultural NH3 emission inventory (Ayres et al., 2008b). The updated agriculture NH3 emission calculation considered the geographical distribution of NH3 emissions from livestock (beef, dairy, swine, broilers, layers, turkeys) and fertilizer sources. Most of the spatial variability in livestock ammonia emissions resulted from differences in manure management practices that varied throughout the year. Canadian updated NH3 emission inventory was based on total ammoniacal N (TAN ¼ NH3 þ NHþ 4 ) from feeding to excretion, housing, manure storage and manure applied in the field (Ayres et al., 2008b). The TAN excreted was based on a dietary mass balance, and equaled N in the feed consumed less N retained in products (meat, milk, eggs, etc.). Different manure management practices (e.g., housing, storage, land spreading) were considered for different livestock and poultry sectors. Emission factors procured from the literature were adjusted for geographic variability attributed to differences in farming practices and climate conditions. The 2002 emissions inventory used a vast collection of activity data (e.g. livestock farm practices) which was supplemented by the opinions and/or judgment of experts.

2.2. Emission intensity metrics

Fig. 1. Beef, pork and poultry meat production in Canada from 1990 to 2008 (a); per capita meat consumption of beef, pork and poultry from 1990 to 2008(b). From Statistics Canada (2008).

livestock operations, federal and provincial governments have implemented environmental laws and regulations to reduce air and water pollution. In 2006, federal air pollution regulations were strengthened with the establishment of the Clean Air Act to protect human health and the environment from airborne pollutants (Environment Canada, 2009). Public concerns about air quality contamination stemming from increased livestock specialization have led industrialized countries to promulgate international protocols such as the Gothenburg Protocol to reduce Long Range Transboundary Air Pollution (UNECE, 1999). The contribution of livestock to NH3 emissions in Canada has been examined by a number of authors (e.g., Ayres et al., 2008a; Kurvits and Marta, 1998). This study employed the updated 2002 Canadian national agricultural NH3 emission inventory to examine the relationship between geographical distributions of NH3 emissions, livestock emission intensities, and provincial livestock concentration. A secondary objective of the study was to review the literature and identify emissions reduction strategies that are feasible, cost effective and practical for lowering NH3 losses. 2. Methodology 2.1. Agricultural ammonia inventory data An updated 2002 national agricultural NH3 emission inventory was developed as part of the Canadian National Agri-Environmental Standards Initiative (Lillyman et al., 2009). The NH3 data used in this study provides a precise estimation of the spatial and seasonal distribution of NH3 emissions since it incorporates detailed characterization of agricultural practices. A mass balance approach adapted from

In this study emission metrics were computed for different livestock sectors to identify the potential of mitigation practices to reduce NH3 emissions. Emission intensity metrics can be used to determine the beneficial effects of best management practices (BMP) and the impact mitigating technologies may have in lowering emissions. Emission intensity indicators have been developed for European agriculture to track improvements in manure management practices in the reduction of greenhouse gases (GHG) (Halberg et al., 2005) and energy use in California grape and wine production (Price et al., 2003). For the purposes of studying regional differences in ammonia emissions, the provinces of British Columbia (BC), Alberta, Saskatchewan, and Manitoba were defined as western Canada, while the provinces of Atlantic Canada (Newfoundland, Prince Edward Island, Nova Scotia, and New Brunswick), Québec and Ontario were defined as eastern Canada. In order to estimate ammonia emissions per unit area the 2001 Census total farm area was used. This included land in crops, summerfallow, tame or seeded pasture, natural land for pasture, and other land including woodlands and wetlands (Statistics Canada, 2009a). Emissions were also expressed per animal unit. Arogo et al. (2003) indicated that standardizing emission rates per animal unit would allow comparing emissions over different livestock sectors and management systems. Emissions per animal unit were based on animal unit coefficients adapted from Beaulieu and Bédard (2003). Emissions per hectolitre of milk were based on milk production statistics reported by the Canadian Dairy Commission (2009), while emissions per farm cash receipts and per dozen of eggs produced were based on statistics provided by Statistics Canada (Statistics Canada, 2007b, 2004, 2003).

3. Results and discussion 3.1. Geographic distribution of ammonia emissions National NH3 emission levels can mask important geographical differences. Of the total Canadian agricultural emissions, the largest percent was derived from Alberta (27%), followed by Ontario (20%), Saskatchewan (19%), Québec (16%), and Manitoba (12%) (Table 1). Total agricultural NH3 emissions per unit farm area (kg km2 yr1) are higher in Québec and Ontario than in the provinces of western Canada. Among Atlantic Canada provinces, Nova Scotia and New Brunswick had lower emission densities than Newfoundland and Prince Edward Island. Livestock NH3 emissions from different animal sectors are described in Table 2. Beef cattle emissions accounted for the largest quantity of total livestock emissions (163 kt NH3 yr1) followed by emissions from swine (73 kt NH3 yr1), dairy (52 kt NH3 yr1) and poultry (19 kt NH3 yr1). Kurvits and Marta (1998) reported livestock NH3 emissions in Canada corresponding to 331 kt (cattle and calves), 119 kt (poultry), and 107 kt (swine) in 1995. The U.S. Environmental Protection Agency (2005) estimated United States (US) livestock NH3 emissions that were four times and five times larger than Canada respectively for beef (617 kt NH3 yr1) and swine (349 kt NH3 yr1) in 2002. Canada’s beef emission intensity (kg/Mt meat production) is at least twice larger than the United States, whereas US poultry emission intensity (kg/Mt meat production) is about twice larger than Canada (Table 2).

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Table 1 Livestock and fertilizer NH3 emissions, share of total NH3 emissions, and emission densities by Canadian provinces, 2002. From Statistics Canada (2009a); Ayres et al. (2008a). Provinces of Canada

Livestock NH3 emissions ( 103 kg)

Fertilizer NH3 emissions ( 103 kg)

Share of emissions (%)

Total farm area (km2)

NH3 emission densities (kg km2 yr1)

Newfoundland Prince Edward Island Nova Scotia New Brunswick Quebec Ontario Manitoba Saskatchewan Alberta British Columbia Canada

509 2299 3260 2798 57,312 67,486 32,755 40,044 86,170 13,599 306,232

30 882 313 580 9460 17,629 16,040 38,626 25,579 1296 110,435

0.1 0.8 0.9 0.8 16.0 20.4 11.7 18.9 26.8 3.6 100

406 2615 4070 3881 34,170 54,662 76,018 262,656 210,675 25,871 675,024

1328 1217 878 870 1954 1557 642 300 530 576 617

The contribution of livestock emissions from the provinces of western and eastern Canada is shown in Fig. 2. Alberta’s share of beef and dairy emissions in western Canada is higher than BC, Saskatchewan, or Manitoba, whereas BC’s share of poultry emissions is higher than Alberta, Saskatchewan or Manitoba (Fig. 2a). Manitoba’s share of swine emissions in western Canada is about twice the share from Saskatchewan. Ontario’s share of beef, layer and turkey emissions in eastern Canada is higher than either Québec or the Atlantic provinces whereas Québec’s share of dairy, swine and broiler emissions is slightly higher than Ontario’s (Fig. 2b). The variation in livestock emissions between western and eastern Canada reflects differences in livestock population numbers, production systems, and manure management practices. The animal population is not evenly distributed in Canada, with 68% of beef cows concentrated in Alberta and Saskatchewan, 72% of dairy cows in Ontario and Quebec, 74% of swine in Quebec, Ontario and Manitoba, and roughly 60% of poultry in Ontario and Quebec (Statistics Canada, 2007a). The bulk of dairy, hogs and poultry production concentrated in Ontario and Quebec is characterized by a production environment where animal population density is high, confined production systems are prevalent, and there is relatively less farmland available (Beaulieu, 2001). When emissions from fertilizer and livestock sources were considered together, the geographical distribution of emissions differed significantly between western and eastern Canada. Western Canada had 49%, 12%, and 4% of its total agricultural emissions originating from beef, swine and dairy, respectively (Fig. 3a). Collectively, broilers and layers accounted for 2%, with emissions from synthetic fertilizer totaling 32% of total agricultural emissions in western Canada. In eastern Canada, beef (23%), dairy (25%) and swine (27%) accounted for 75% of total agricultural emissions (Fig. 3b). The combined share of broilers, layers and turkeys totaled 7%, whereas fertilizers accounted for 18%. The relatively larger contribution of fertilizer emissions in western

Canada was attributed to the greatest fertilizer emissions from Saskatchewan and Alberta (Ayres et al., 2008a); provinces that account for the bulk of wheat, barley and canola production in western Canada and N fertilizer used (Korol, 2002). 3.2. Provincial livestock emission intensity indicators in 2002 Ammonia emission intensities from livestock sources are shown in Table 3. They differ by province and livestock sector. Dairy NH3 emission intensity (kg/hectolitre of milk) is highest in Ontario and Quebec which account for 70% of Canada’s fresh milk production. Dairy NH3 emissions per livestock unit (kg livestock unit1) reveal Ontario and Québec have the highest per unit dairy NH3 losses compared to provinces in western Canada. Because of Canada’s cold winter weather conditions, dairy animals in Ontario and Québec

Table 2 Livestock NH3 emissions and intensity indicators for Canada and the United States, 2002. From FAO (2009); Ayres et al. (2008a); U.S. Environment Protection Agency (2005); USDA (2004). NH3 emissions/intensity indicators

Canada

United States

Beef emissions (103 kg) kg/Mt of meat production

162,606 126

616,553 50

Dairy emissions (103 kg) kg/hectolitre of milk production

51,766 1

495,765 1

Swine emissions (103 kg) kg/Mt of meat production

72,879 39

348,530 39

Poultry emissions (103 kg) kg/Mt of meat production

18,981 17

498,622 29

Units: Mt ¼ metric tonne; kg ¼ kilogramme.

Fig. 2. Ammonia emissions (% of total livestock product) from different livestock sectors in: (a) western Canada, (b) eastern Canada, for the year 2002. From Ayres et al. (2008a).

R. Carew / Environmental Pollution 158 (2010) 2618e2626

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eastern Canada being more forage-based than in western Canada along with beef cattle in eastern Canada spending less time on pasture. Beef production in western Canada comprises several distinct production phases (e.g., cow-calf, backgrounding, feedlots) with cow-calf producers utilizing grazing land during the spring and summer months and feedlot operators finishing cattle on high energy feed rations (Vergé et al., 2008; Desjardins et al., 2006). Swine emission metric (kg livestock1) is higher than either beef or dairy. While Quebec and Ontario accounts for roughly 55% of Canada’s swine population, their emission metric (kg livestock unit1) is higher than either Manitoba or Alberta. Differences in emission metric between eastern and western Canada may be due to a combination of differences in swine populations and diet. Soybean meal and corn that dominate swine rations in eastern Canada have higher digestibility than canola meal and barley used primarily in western Canada (Vergé et al., 2009). The poultry layer emission metric (kg/000 dozen eggs) is highest in Alberta than in other Canadian provinces. Ontario, which accounts for 38% of Canada’s egg production, had an emission metric (kg/000 dozen eggs) that is comparable to New Brunswick but lower than most provinces in western Canada. Poultry NH3 emissions are influenced by proximity to urban areas with the largest poultry emissions noted in BC, Ontario and Quebec where large human population centres are close to agricultural communities. 4. Abatement strategies Under the Gothenburg Protocol countries are required to establish, publish and disseminate a code of BMPs and technologies to reduce NH3 emissions (Webb et al., 2005). BMPs should consider the local environment since abatement techniques developed for climatic conditions in one region may not be applicable to geographic regions where there is rapid volatilization (Fig. 4). Possible approaches evaluated in Canada for minimizing NH3 volatilization have ranged from covers for manure storage, improved placement of manure N and timely incorporation of manure into agricultural land (Agriculture and Agri-Food Canada, 2008b). In this paper, abatement strategies discussed to improve animal N use efficiency and reduce NH3 losses included diet manipulation, housing, storage and land spreading options.

Fig. 3. Percentage contribution of ammonia emissions by livestock and fertilizer sectors in: (a) western Canada, (b) eastern Canada, for the year 2002. From Ayres et al. (2008a).

generally are confined in closed or open barns for a longer period with lower time spent on pasture (Vergé et al., 2007). Ammonia losses (kg livestock unit1) from the UK dairy system are five times higher than New Zealand grass system and the greater NH3 losses from the UK system have been attributed to the higher N inputs (Jarvis and Ledgard, 2002). While most of Canada’s beef cattle population resides in Alberta and Saskatchewan, beef NH3 losses per livestock unit (kg livestock unit1) are lower in Alberta and Saskatchewan than either Ontario or Quebec. The variation in beef emission metric is partly attributed to pastures (e.g., alfalfa) in eastern Canada having higher N requirements than native pasture species found in western Canada (Kerr and Cihlar, 2003). Vergé et al. (2008) estimated GHG emission intensity (kg CO2 equivalent/kg live-weight) for beef cattle that was 21% higher in eastern Canada than western Canada and attribute regional differences to beef production in

4.1. Dietary measures Livestock feed generally provides for maintenance and production requirements. Increasing N utilization in animal diets requires providing the right amount and quality of protein to maximize production at the least feed cost (Rotz, 2004). Matching diets to the amino acid or crude protein (CP) requirements of animals can decrease the quantity of N excreted in feces and urine. Feeding essential amino acid supplements can decrease CP feeding without sacrificing animal production. However, the relative prices of synthetic amino acid supplements and other feed ingredients must be balanced with the desired level of CP reduction required to optimize animal performance and reduce NH3 emission (Clark et al., 2005). For growing-finishing pigs, lowered dietary CP combined with essential amino acids supplementation, and increased barley-based diets reduced urinary N, NH3 emission and volatile fatty acids (VFA) without affecting animal growth rate performance (O’Connell et al., 2006; Hayes et al., 2004; Canh et al., 1998). Otto et al., (2003) have suggested that while CP diet manipulation may lower NH3

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Table 3 Ammonia emissions by livestock sector and emission intensity indicators for eastern and western Canadian provinces, 2002. From Canadian Dairy Commission (2009); Ayres et al. (2008a); Statistics Canada (2007b, 2004, 2003). NH3 emissions/intensity indicators

NewFoundland

Prince Edward Island

Nova Scotia

New Brunswick

Quebec

Ontario

Dairy emissions (103 kg) kg/ $000 dairy receipts kg/hectolitre of milk production kg livestock unit1

148 5.3 0.41 19.5

678 12.7 0.72 25.9

1069 11.4 0.64 24.8

867 11.6 0.67 25.0

19423 12.9 0.73 26.8

19007 14.0 0.79 27.6

Beef emissions (103 kg) kg/$000 cattle & calves receipts kg livestock unit1

31 19.1 18.8

845 33.3 20.9

1013 36.4 22.8

861 29.3 22.3

10262 18.4 24.9

24285 20.9 26.8

17075 30.7 20.0

32045 28.1 18.6

69697 18.2 17.8

6492 20.4 14.9

Swine emissions (103 kg) kg/$000 swine receipts kg livestock unit1

13 11.6 48.9

715 25.8 49.9

683 22.8 53.2

687 24.9 51.4

23223 25.1 51.0

18048 22.4 47.0

12263 17.1 41.9

5944 24.4 46.9

10381 22.3 45.2

922 24.4 51.3

61 -

495 8.5

383 9.3

4404 9.4

6146 10.2

1625 18.1

819 14.7

1998 13.7

2733 10.5

34 8.8 11.5

202 8.6 11.5

201 13.4 13.1

1655 14.4 15.9

2884 13.6 13.3

909 15.2 11.5

349 15.7 15.2

775 18.5 18.2

1072 15.3 15.9

Poultry emissions (103 kg) kg/$000 poultry receipts Layer emissions (103 kg) kg/ $000 egg receipts kg/000 dozen of eggs

317 82 7.8 11.1

emissions it may not necessarily diminish odor offensiveness and fecal VFA concentrations. While the reduction of CP content in feed rations is an effective way to reduce urinary N excretion in monogastrics, the use of fibre sources high in fermentable carbohydrates can shift N excretion from urine to feces, and reduce NH3 emission (Payeur et al., 2002). Feed additives, such as yucca extract, were found to be inconsistent in reducing NH3 emissions in swine buildings (Panetta et al., 2006). Potential reasons for inconsistent NH3 reduction effects were due to the measurement of emissions or age of pigs fed. In contrast to monogastrics that require high quality protein, ruminant animals can use non-protein N in increasing amounts so that the reduction in NH3 emissions and the excretion of fecal N can be achieved by reducing dietary indigestible N in the diet (Kebreab et al., 2002). Reducing the CP intake by as little as 5% and supplementing ruminant diets with amino acids can reduce NH3 emissions by as much as 74% from excreted manure (Ndegwa et al., 2008). In BC, dairy diets containing two CP levels (16.4% CP vs. 12.3% CP) resulted in a significant difference in NH3 emissions (38% vs. 23% of total manure N) during the first 24 h following manure excretion (Paul et al., 1998). Studies in Western Europe based on two feeding routines (separate feeds vs. mixed ration) showed that ration composition is important in reducing the environmental effects of animal feeding with a 14% CP ration decreasing NH3 emission by two-thirds compared to a 19% CP ration with no consequential effects on milk production or milk composition (Frank et al., 2002). For beef cattle, the effect of CP content in the diet on NH3 emission may be related to feed composition. McGinn et al. (2002) found Alberta feedlot cattle fed barley-based diets did not significantly reduced NH3 emissions unless lower CP ingredients, such as corn-based diets were incorporated into the diet. Under concentrated animal feeding operations in Texas, it was found that reducing CP in animal diets was the most cost-effective way of lowering NH3 emissions. For example, reducing CP levels in the diet from 13 to 11.5% CP decreased daily NH3 flux by 30, 52 and 29% in summer, autumn, and spring months, respectively (Todd et al., 2006). Phase-fed cattle excreted 12e21% less N and lowered N volatilization losses by 15e33% without impacting manure N (Erickson and Klopfenstein, 2010). Since the goal in feeding ruminants is to ensure the right amount of protein is provided, efforts to reduce NH3 emissions must be evaluated against animal performance targets of faster growth rate or increased milk production to determine the optimal CP concentrations and feed formulations (Cole et al., 2005).

Manitoba 1792 10.9 0.63 24.0

Saskatchewan 1236 10.4 0.59 23.9

Alberta 4094 11.2 0.66 25.9

British Columbia 3452 9.4 0.58 25.6

4.2. Housing Ammonia emission from housing facilities can be lowered by decreasing manure surface area and improving ventilation. Housing design and manure removal practices can affect the rate of N transformation and ammonia loss (Rotz, 2004). Frequent removal of manure and daily flushing are options to limit NH3 volatilization in animal housing. Substantial emission reductions of up to 50% for cubical dairy houses with slatted floors can be achieved by flushing floors with water or diluted formaldehyde, optimizing feeding strategies, and acidifying slurry (Monteny and Erisman, 1998). Ammonia and hydrogen sulfide (H2S) emissions are influenced by manure removal strategies. For example, NH3 and H2S emissions were reduced by 51e62% and 18e40% respectively for finishing pigs when static pits were recharged after emptying and when pits were emptied more frequently (Lim et al., 2004). Filtration or biofiltration is another device for removing NH3 from the exhaust air of animal houses. Such treatment of exhaust air may reduce environmental emissions of odor and particulate matter that are considered a nuisance in high density livestock areas. For swine housing in the Netherlands the use of biotrickling

Fig. 4. Beneficial management projects (% of total projects) funded under the Canadian National Farm Stewardship Program for manure storage and land application by provinces, 2005e2007. From Snell (2008). Note: AC ¼ Atlantic Canada, ON ¼ Ontario, QC ¼ Québec, MB ¼ Manitoba, SK ¼ Saskatchewan, AB ¼ Alberta, and BC ¼ British Columbia.

R. Carew / Environmental Pollution 158 (2010) 2618e2626

filter resulted in NH3 and odor removal efficiency ratings of 79% and 49%, respectively (Melse and Mol, 2004). Ammonia removal efficiency in swine and poultry houses from acid scrubbers and biotrickling filters averaged 96% and 70%, respectively (Melse and Ogink, 2005). The beneficial effects of air scrubbers to remove NH3 may be enhanced if they can remove odor and particulate matter emissions (Melse and Timmerman, 2009). Although biofilters have the potential to reduce NH3 and odor from exhaust air, the adoption of this technology among Alberta swine producers has not been very successful because the technology is costly to install, operate and maintain (Atta, 2008). Urine/feces separation methods have been considered as an alternative manure handling system for swine and cattle operations in the U.S. as an option to reduce NH3 emissions (Gay and Knowlton, 2005). Manure management systems that completely segregate swine urine and feces at excretion have the potential to decrease NH3 volatilization by more than 99% due to decreases in ammonium N formation (Panetta et al., 2005). The feasibility of producers adopting feces/urine separation methods will depend on the costs of installation and maintenance, and human and animal health considerations. 4.3. Manure storage Depending on the livestock sector, manure is generally kept in a housing structure for a few days or months before being removed to a storage container. Storage systems in Canada can be categorized as solid, slurry, and liquid, with solid/semi solid storage more prevalent in Atlantic Canada and liquid storage more prevalent in Quebec (Desjardins et al., 2006). In the swine industry, liquid storage is by far the most common manure handling method, representing 96% of all swine manure storage systems, whereas dairy manure stored under a solid and liquid system corresponding to 40% and 42%, respectively (Marinier et al., 2004). Dairy storage systems in Europe characterized by deep litter manure resulted in the lowest emission rates of total N, NH3 and methane (Külling et al., 2001). Strategies to limit emissions from storage lagoons generally involve reducing the free surface area of the slurry by covering it with either a fixed structure or floating device. Substantial differences in NH3 reduction efficiency and odor abatement from covering swine and cattle slurry were achieved by floating materials such as vegetable oil, chopped wheat straw and wood chips (Guarino et al., 2006; Hörnig et al., 1999). The effectiveness of different covers for swine slurry during storage and following land application revealed NH3 emissions were reduced by 40% for oil covers and up to 65e71% for zeolites that lowered the emitting surface area (Portejoie et al., 2003). Several studies (e.g., Bicudo et al., 2004) have shown geotextile covers can reduce odor and NH3 fluxes from swine manure storage ponds while synthetic covers, such as flexible reinforced polyethylene membrane were effective in reducing odors and NH3 emissions from earthen embanked swine lagoons (Funk et al., 2004). Though geotextile thickness and type of manure did not significantly reduce emissions of NH3, H2S and odor, straw thickness affected reduction of odor and airborne pollutants (Clanton et al., 2001). Unlike permanent covers such as tent roofs built over large slurry lagoons that are prohibitively expensive, floating covers such as chopped wheat straw are inexpensive and practical for swine producers. 4.4. Land spreading Land manure application methods to incorporate manure and mitigate NH3 differ by geographic regions of Canada. Solid or

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composted manure was the principal land application technique and accounted for about two-thirds of the farm area on which manure was applied (Table 4). Beef cattle operations, the majority of which are in western Canada, applied solid or composted manure to a larger farm area than operations in eastern Canada. Liquid manure application accounted for one-third of the farm area and was associated with hog and dairy operations in eastern Canada. Over 50% of the liquid manure applied was injected or incorporated into the soil reflecting a trend towards better nutrient management standards. The ability to predict NH3 volatilization losses from field-applied manure depends on manure characteristics, environmental conditions, and the application method (Huijsmans et al., 2003; Thompson and Meisinger, 2002). While NH3 volatilization increased with an increase in the manure application rate and the TAN content of the manure, grass height affected NH3 volatilization when manure was applied in narrow bands (Huijsmans et al., 2001). A review of the literature revealed the effectiveness of reducing NH3 emissions from different land spreading techniques (Table 5). Applying dairy slurry to forage crops in BC’s moist environment, showed the banding subsurface slurry applicator (SSA) method reduced NH3 losses and increased forage yield and N uptake relative to surface banding and conventional broadcasting techniques (Bittman et al., 2005). Ammoniacal N loss from the micrometeorological method in the 2wks after application range from 17e32% for the SSA applicator to 36e61% for broadcast manure. The effectiveness of the SSA technique may be attributed to the slurry being deposited beneath the grass canopy and consequently reducing volatilization from field-applied manure. For beef cattle manure applied to land in Alberta, the impact of irrigation and tillage reduced NH3 losses respectively by 21e52% and 76e85% compared to leaving the manure spread on the soil surface (McGinn and Sommer, 2007). Consequently, feedlot operators in western Canada can reduce emissions and enhance air quality by adopting manure tillage practices. In eastern Canada where there is a need to improve the utilization of manure nutrients by minimizing NH3 emission from land application, increasing the depth of incorporation and coverage of manure reduced NH3 losses respectively by 4.4 kg ha1 and 2 kg ha1 compared to surface application (Smith et al., 2009). Where direct injection is not feasible in some Atlantic provinces because of soil and land conditions, surface application of liquid swine manure lowered NH3 emissions by 32% compared to solid manure (Smith et al., 2008). Ammonia emissions correlated with atmospheric conditions reduced NH3 emissions by 37% when manure applied prior to rainfall. Under European conditions, rapid incorporation, band spreading (e.g., trailing hose) or injection of manure are more cost effective abatement measures to reduce NH3 emissions than measures to lower emissions from buildings (Webb et al., 2005; Sommer and Hutchings, 2001). Compared to surface broadcast, abatement was generally more effective from applied cattle slurry to grassland, with average emission reductions of 73, 57 and 26% achieved for shallow injection, trailing shoe and band spreading, respectively (Misselbrook et al., 2002). Similar results were reported by Smith et al. (2000), with NH3 reduction for shallow injection, trailing shoe and band spreading corresponding to 57, 43 and 39% respectively relative to conventional surface broadcast application. While band spreading is more effective on arable than on grassland and when used with dilute slurries (Webb et al., 2005), the application of swine slurry to cereal stubble by band spreading is not an effective abatement strategy when compared to raingun or splashplate irrigation systems (Misselbrook et al., 2004). Shallow slurry injection into grassland reduced NH3 emission between 20e75% when compared to trailing-hose application

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Table 4 Manure land application method by number of farms and land area, 2005. From Statistics Canada (2009b). Province

Manure land application method

Number of farms

Area of land (ha)

Area per farm (ha)

Atlantic Canada

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

280 461 16 2675 2610

12,648 27,898 490 42,591 46,802

45.17 60.52 30.63 15.92 17.93

Quebec

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

4089 5917 e 8189 8054

212,968 272,670 e 189,018 216,853

52.08 46.08 e 23.08 26.92

Ontario

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

3525 2551 408 19,850 14,557

180,098 99,007 12,997 340,312 213,187

51.09 38.81 31.86 17.14 14.64

Manitoba

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

880 363 33 5265 3316

87,066 18,304 2245 157,887 86,080

98.94 50.42 68.03 29.99 25.96

Saskatchewan

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

397 123 11 9114 4823

38,894 6161 919 246,941 115,427

97.97 50.09 83.55 27.09 23.93

Alberta

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

844 385 26 12,704 6994

76,255 23,154 1582 394,617 174,850

90.35 60.14 60.85 31.06 25.00

British Columbia

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

323 563 85 5035 2806

9757 18,181 3250 43,427 26,950

30.21 32.29 38.24 8.63 9.60

Canada

Liquid manure injected or incorporated into the soil Liquid manure not incorporated into the soil Liquid manure applied by irrigation Solid or composted manure incorporated into the soil Solid or composted manure not incorporated into the soil

10,338 10,363 579 62,832 43,160

617,687 465,373 21,484 1,414,791 88,0147

59.75 44.91 37.11 22.52 20.39

(Hansen et al., 2003). However, injecting slurry increases the demand for energy, and therefore lowering NH3 emissions by slurry injections will likely be offset by increases in GHG emissions. Mitigating strategies to reduce NH3 losses are likely to affect the emissions of other airborne pollutants and therefore a whole-farm system approach may be required to avoid conflict between environmental objectives (Sommer and Hutchings, 1995). There may be

an interrelationship between NH3 abatement techniques and its impact on nitrous oxide (N2O) emissions (Brink et al., 2001). Research in Germany showed there was no correlation between NH3 emission losses and N2O emissions from applied cattle slurry employing different land application techniques (Clemens et al., 1997). Further research is required to understand the interrelationship between different abatement techniques and their effect on NH3 and N2O pollutants.

Table 5 Land application techniques for NH3 abatement: a geographical comparison of reduction estimates. Land application method

Manure characteristics

Emission reduction (%)

Region/country

References

Surface-application Irrigation Tillage Subsurface deposition

Swine manure Beef feedlot manure

32% 21e52% 76e85% 46e48%

Prince Edward Island, Canada Alberta, Canada

Smith et al. (2008) McGinn and Sommer (2007)

BC, Canada

Bittman et al. (2005)

Dairy slurry

Shallow injection

Cattle slurry

20e75%

Denmark

Hansen et al. (2003)

Shallow injection Trailing shoe Band spreading

Cattle slurry Cattle slurry Cattle slurry

73% 57% 26%

UK

Misselbrook et al. (2002)

Shallow injection Trailing shoe Band spreading

Cattle slurry Cattle slurry Cattle slurry

57% 43% 39%

UK

Smith et al. (2000)

R. Carew / Environmental Pollution 158 (2010) 2618e2626

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