Archived: Air Pollutant Emission Inventory report: annex 2 - inventory development: part 4
A2.2 In-house estimates: continued
Table A2-6: Estimation methodologies for agriculture by sector/subsector
Animal production
Description
Animal Production reports emissions from the volatilization of NH3 from nitrogen in manure, particulate matter that is released from feeding and housing, and non-methane volatile organic compounds (NMVOCs) that are released during livestock feeding, housing and manure management.
Ammonia volatilization is a chemical process that occurs when manure is excreted or stored without a cover. Once excreted, manure moves through a number of stages until it is eventually cycled back to farm fields. Ammonia volatilization occurs at each stage of this cycle, including animal housing, transport to long-term storage, storage, and application of manure to the field.
Livestock production results in primary PM emissions as a result of the aerial transport of feed particles, feather fragments, fecal material, skin debris or dander, animal wastes, mould spores, bacteria, fungus, litter fragments, etc. Ventilation systems in livestock buildings are required for air exchange and, as a result, a portion of the PM in confined livestock buildings will be emitted into the atmosphere via the ventilation system.
NMVOC emissions from livestock production are the result of biological processes that partially break down feed during storage and digestion. Emissions from excreted manure occur during all stages of the manure management cycle. Sites of emission therefore include silage stores, livestock housing, manure stores, and agricultural fields on which manure is applied or that are used for grazing.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5, NH3, NMVOCs
The methodologies for ammonia emissions are developed by Environment and Climate Change Canada in collaboration with Agriculture and Agri-Food Canada (AAFC) through a national research project: the National Agri-Environmental Standards Initiative (NAESI).
Methods describing the estimates of NH3 emissions from Canadian livestock are published for most major livestock categories (dairy, non-dairy, swine and poultry). Details on parameters used and animal category-specific methodologies are available from the following publications: Sheppard and Bittman (2010, 2012); Sheppard et al. (2007a, 2007b, 2009a, 2009b, 2010a, 2011a; 2011b); Chai et al. (2016). The methodology used for the estimation of ammonia emissions from the Dairy industry has been updated to make it compatible with the current methodology used for the estimation of Greenhouse Gases (see Annex 3.4, of the National Inventory Report (ECCC 2018)). Though the specific emission factors used in estimating ammonia emissions have not been modified, the total emissions per head have changed, as a result of changes in rates of N excretion per animal and the proportions of manure stored in different manure systems over time. Methodologies for minor animals, such as horses, goats, fur-bearing animals (mink, fox), wild boars, deer, elk, rabbit and poultry, were taken from Battye et al. (1994).
The methodologies for emissions of particulate matter from livestock production are developed by AAFC for publication in the National Agri-Environmental Health Analysis and Reporting Program (NAHARP), published every five years with the Agricultural Census. The method is consistent with the European Monitoring and Evaluation Programme (EMEP)/Core Inventory of Air Emissions in Europe (CORINAIR) Guidebook (EMEP/CORINAIR 2002), but uses country-specific emission factors. Methodologies are published in Pattey and Qiu (2012) and Pattey et al. (2015).
The methodology for estimating NMVOC emissions was based on tier 1 methodology outlined in the 2013 European Monitoring and Evaluation Programme/European Environment Agency Air Pollutant Emission Inventory Guidebook (EMEP/EEA, 2013).
Activity data
Annual cattle, sheep and swine populations are calculated as the simple mean of semi-annual or quarterly surveys (Statistics Canada l). These smaller surveys are corrected to the Census of Agriculture (COA) population estimates that are collected every 5 years to ensure the accuracy of the estimates.
The populations of other livestock, such as horses, goats, bison, llamas and alpacas, deer and elk, wild boars, rabbits, and poultry, are taken from the COA exclusively, and annual populations are developed by linear interpolation in order to avoid large changes in census years. Where populations for certain alternative livestock animal categories were not available in the COA, values were held constant, or extrapolated back to zero.
The breeding mink and fox population estimates were taken from an annual Statistics Canada survey titled Supply and Disposition of Mink and Fox on Fur Farms (Statistics Canada m ),. Rabbit populations were taken from responses to the COA as provided on the AAFC Red Meat Market website (AAFC 2016).
Emission factors (EF)
Ammonia:
Non-dairy cattle, swine and poultry, ammonia emission factors are a weighted average of a variety of different emission fractions that occur during the stages of the manure and animal production cycle.
The input to the emission factor equation originates from a combination of the Livestock Farm Practices Survey (LFPS), which defines feed distribution to and consumption by animals throughout the year, and generic parameters derived from scientific literature or expert opinion. This information is distributed spatially across Canada by ecoregion.
Animal populations are reassigned to a matrix of animal housing and manure management systems based on their relative proportion in the overall farm population.
The fractions of NH3 emitted at each step in the manure cycle are taken in part from the European Monitoring and Evaluation Programme (EMEP)/Core Inventory of Air Emissions in Europe (CORINAIR) Guidebook (EMEP/CORINAIR 2002) and in part from Canadian studies. The resulting weighted emission factors are applied to populations of animal subcategories taken from census data at the ecoregion spatial scale.
Model to calculate NH3 emissions: Sheppard et al. (2010a)
Dairy Cattle:
Ammonia emissions are calculated according to Sheppard et al. 2010a; with modifications according to Chai et al. (2016) and based on the activity data and methodology outlined for Agriculture in the National Inventory Report: 1990–2016, Greenhouse Gas Sources and Sinks in Canada (ECCC 2018). Total N excretion for dairy cattle is calculated according to the Tier 2 methodology in the IPCC 2006 Guidelines (IPCC 2006).
Ammonia emission factors from Sheppard et al. (2011a) are expressed as fractions of total N using calculated TAN fractions (Chai et al. 2016), to produce ammonia N loss factors by ecoregion, for housing and manure storage, manure application, and manure deposited on pasture, range, and paddock.
Manure management storage information was derived from Sheppard et al. (2011b) to identify proportions of manure excreted on pasture and in exercise yards and information on the quantify of manure stored as liquid and solid manure drawn from the Farm Inputs Management Survey (1995) (Statistics Canada 1996), the Farm Environmental Management Surveys (2001, 2006, 2011) (Statistics Canada n and the Livestock Farm Practices Survey (2005) (Statistics Canada 2007). A time series of manure storage was developed based on relationships between liquid storage and time on pasture with farm size to account for changes in manure storage between 1990 and the present.
Emissions from manure applied to agricultural soils, were consistent with Sheppard et al. (2010b) as modified according to Chai et al. (2016).
Particulate Matter:
Total particulate matter (TPM) emission factors for poultry are taken from Van Heyst (2005) and Van Heyst and Roumeliotis (2007). Emission factors for cattle and swine are average values from Takai et al. (1998) and Seedorf (2004). In the case of PM10 and PM2.5, emissions are estimated from TPM emission factors multiplied by 0.45 and 0.1 to produce PM10 and PM2.5 emission factors, respectively.
Average animal weights are used to convert emission factors in the form of g d-1 AU-1 to units of kg head-1 year-1.
The emission factors for cattle are also assigned to the other animal types by assuming that the emission factors per animal unit for sheep, goats, bison, llamas, alpacas and horses are the same as those for cattle. Average body weight of cattle are consistent with information provided by Boadi et al. (2004) and with weight corrections for cattle according to the methodology outlined in the National Inventory Report: 1990–2013, Greenhouse Gas Sources and Sinks in Canada (EC 2015b). All other animal weights were consistent with values used to estimate nitrogen excretion in EC (2015b).
Currently no emissions are estimated for mink, fox, wild boars, deer, elk or rabbit.
Non-methane volatile organic compounds:
The emission factors for all animals were taken from Table 3-3 of EMEP/EEA (2013). For livestock categories where a choice of emissions factors was provided, the non-silage emission factor was selected, except for dairy cows and beef cattle in feedlots where the silage emission factor was used. A weighted emission factor for beef cattle was calculated using the fraction of time spent during each stage of production according to Boadi et al. (2004).
Fertilizer application (under crop production)
Description
Fertilizer Application includes emissions emitted when synthetic nitrogen fertilizers are applied for annual and perennial crop production.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5, NH3
Ammonia:
The method is a simplified version of the approach adopted by Sheppard et al. (2010b) for application on an annual time step.
The methodology uses a regression model developed by Bouwman et al. (2002) and derived NH3 emission factors, taking into account the most important parameters influencing emissions from synthetic nitrogen fertilizer application, based on a meta-analysis of scientific literature.
Particulates:
Methodology is under review.
Activity data
Data on the types of nitrogen fertilizer used on farms are published by Statistics Canada e).
Areas of seeded annual and perennial crops:
Statistics Canada h.
Soil properties, including pH and cation exchange capacity, are included in calculations using soil polygon information from a national-scale spatial database describing the types of soils associated with landforms (available online).
Emission factors (EF)
Ammonia emission factors are calculated using the multiple linear regression equation from Bouwman et al. (2002). The approach uses different regression parameters for synthetic nitrogen fertilizer types, method of nitrogen application, crop type, and soil pH and cation exchange capacity.
A matrix of emission factors for each combination of these conditions occurring across Canada is derived. The average provincial and national emission factors are weighted averages of the relative proportion of each combination of fertilizer type and fertilizer application practice on different soil types in different ecodistricts across the country.
TPM, PM10 and PM2.5 methodology is under review.
Harvesting (under crop production)
Description
Agricultural harvest activities entrain particulate matter into the air. Particulate matter generated from agricultural harvesting, also known as grain dust, includes grain and dry plant particles, moulds, pollen and spores, silica, bacteria, fungi, insects and possibly pesticide residues. These emissions are generated by vehicles traveling over the soil or by the processing of plant materials by agricultural equipment.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5
Particulate matter emissions from agricultural harvest operations are computed by multiplying an emission factor and an activity factor relating emissions to the area harvested.
Activity data
Activity data for PM emission estimates from crop harvesting rely on a combination of data from the Census of Agriculture and area estimates based on Earth Observation data. Activity data on areas of major field crops at an ecodistrict level from 1990 to 2016 are consistent with the data reported in the Agriculture and the Cropland remaining Cropland category of the Land Use, Land-use Change and Forestry sector for the National Inventory Report: 1990–2016, Greenhouse Gas Sources and Sinks in Canada (ECCC 2018).
Emission factors (EF)
There are no emission factors for agricultural harvest in Canada. The PM10 emission factors proposed by CARB (2003) are used to calculate PM emissions from crop harvest. Where the specific emission factors for some crops are not available from CARB (2003), the emission factors for these crops are based on an approximation from the closest representation (Pattey and Qiu 2012).
Tillage practices (under crop production)
Description
Tillage practices produce PM emissions from mechanical disturbances such as seeding, seed bed preparation and cultivation.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5
Agricultural tillage is the common method used by farmers to prepare land for seeding and weed control. Particulate matter emissions are generated from airborne soil particles during tillage operations due to the mechanical disturbance of the soil surface.
Particulate matter emissions from agricultural tillage operations are proportional to the area tilled. They are also dependent on the type of tillage practice as well as the number of tillage events per year. The calculations are described in more detail in Pattey and Qiu (2012).
The number of tillage events per year is dependent on tillage practices. There are fewer tillage events per year for conservation tillage compared to conventional tillage. Therefore, a reduction in particulate matter emissions from reduced tillage and no-till is observed.
Activity data
Activity data for PM emission estimates from tillage practices rely mainly on a combination of data from the Census of Agriculture and area estimates based on Earth Observation analyses. Activity data on areas of major field crops, including summerfallow, and on tillage practices at an ecodistrict level from 1990 to 2016 are consistent with the data reported in the Cropland remaining Cropland category of the Land Use, Land-use Change and Forestry sector for the National Inventory Report: 1990–2016, Greenhouse Gas Sources and Sinks in Canada (ECCC 2018).
Information on the number of tillage events per year for crop type and tillage practices is taken from soil cover indicators (Huffman et al. 2012).
Emission factors (EF)
Emission factors for tillage practices are calculated using the method described in U.S. EPA (1985).
Wind erosion (under crop production)
Description
Wind erosion occurs when wind blows across exposed agricultural land resulting in PM emissions from the entrained particles.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5
Wind erosion emissions from agricultural lands are calculated by multiplying the cultivated cropland area by an emission factor.
Activity data
Activity data for PM emission estimates from wind erosion rely mainly on a combination of data from the Census of Agriculture and area estimates based on Earth Observation. Activity data on areas of major field crops, including summerfallow, and on tillage practices at an ecodistrict level from 1990 to 2016 are consistent with the data reported in the Cropland remaining Cropland category of the Land Use, Land-use Change and Forestry sector for the National Inventory Report: 1990–2016, Greenhouse Gas Sources and Sinks in Canada (ECCC 2018).
Emission factors (EF)
The PM emission factor for wind erosion is calculated using the wind erosion equation (Woodruff and Siddoway 1965), but considers the impact of soil and crop cover on PM emissions (Huffman et al. 2012). The emission factor for windblown PM emissions from agricultural lands is calculated using the methodology described in Pattey and Qiu (2012).
Fuel use
Description
Agriculture – Fuel Use includes emissions resulting primarily from combustion sources used for space/water heating and crop drying.
General inventory method
Pollutant(s) Estimated:
TPM, PM10, PM2.5, SOx, NOx, VOCs, CO, NH3, Pb, Cd, Hg, dioxins/furans, B(a)p, B(b)f, B(k)f, I(cd)p
Emissions are calculated for 10 types of fuel: natural gas, natural gas liquids, kerosene and stove oils, light fuel oil, heavy fuel oil, Canadian bituminous coal, sub-bituminous coal, lignite coal, anthracite coal and imported coal.
Total usage by fuel type and province/territory is multiplied by pollutant-specific emission factors.
Activity data
Statistics Canada (1991-2016)
Emission factors (EF)
TPM, PM10, PM2.5, SOx, NOx, VOCs, CO: U.S. EPA (1998)
(Emission factors are chosen to represent the typical type of combustion equipment for each fuel type.)
TPM, PM10, PM2.5, SOx, NOx, VOCs, CO for natural gas fuel: U.S. EPA (2004a)
Sulphur contents of liquid fuels: EC (2010)
Sulphur contents of coal: CEA (2002)
NH3: Battye et al. (1994); Coe et al. (1996)
Pb, Cd, Hg, dioxins/furans, B(a)p, B(b)f, B(k)f: CARB (2005); U.S. EPA (1998, 2003, 2004a)
(Emission factors are selected to represent the typical type of combustion equipment for each fuel type.)
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