Prioritizing greenhouse gas emission mitigation
measures for agriculture
S.N. Kulshreshtha
a,*, B. Junkins
b, R. Desjardins
c aDepartment of Agricultural Economics, University of Saskatchewan, Saskatoon, SK, S7N 5A7, CanadabPolicy Branch, Agriculture and Agri-food Canada, Ottawa, ON, Canada cResearch Branch, Agriculture and Agri-food Canada, Ottawa, ON, Canada
Received 31 March 2000; received in revised form 10 August 2000; accepted 14 August 2000
Abstract
Since the signing of the Kyoto Protocol, a major eort has been launched in Canada to identify cost-eective measures to reduce greenhouse gas (GHG) emissions. Agriculture is an important contributor of methane and nitrous oxide in Canada. Over one-third of methane and almost four-®fths of nitrous oxide emissions are from agriculture either directly or indir-ectly. By 2010 primary agricultural production is expected to generate about 67 megatonne (in carbon dioxide equivalent), which increases to 97 megatonnes if all activities related to agri-cultural production are considered. Based on a systems approach, nutrient management was selected as a possible scenario for mitigation. Estimated results indicate that this could lead to a reduction of 0.9 megatonnes of GHG emissions at the primary agricultural production level, and 1.2 megatonnes if the total agriculture and food sectors are included. Compared to the direct emissions (from fertilizer rate and timing of application), the systems approach suggests up to a doubling (from 0.4 to 0.92 Mt) of this reduction potential at the primary production level. If one were to include emissions from the entire agriculture and agri-food system, potential of up to tripling (from 0.4 to 1.23 Mt) the reduction of GHG can be achieved. The need of a systems approach in prioritizing measures to reduce GHG emissions is supported by this study.#2001 Elsevier Science Ltd. All rights reserved.
Keywords:Greenhouse gas emission; Agriculture; Mitigation measures; Prioritizing; Canada
0308-521X/01/$ - see front matter#2001 Elsevier Science Ltd. All rights reserved. P I I : S 0 3 0 8 - 5 2 1 X ( 0 0 ) 0 0 0 4 1 - X
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1. Introduction
1.1. Background
Behind many of the natural disasters that have occurred during the 1990s lurks the specter of human-induced global climate change. Armed with this information along with other global changes as background, in 1992, some 176 countries met in Rio de Janeiro to sign the UN Framework Convention on Climate Change. The major objective of this Convention was to start the process of stabilizing the greenhouse gas (GHG) concentrations in the atmosphere at a level below which they would not contribute to climate change. Such reductions were viewed as instrumental in achieving sustainable economic activity world wide. The Convention was supple-mented by the Kyoto Protocol, which was a result of the Conference of the Parties, which met in Kyoto, Japan, in December of 1997. At this meeting, further commit-ments in the form of targets for reducing GHG emissions were agreed upon. Under this Kyoto Protocol, Canada signed an agreement to reduce its GHG emissions in 2010 (or during the period 2008±2012) to a level that is 6% lower than the 1990 level. As a baseline, these future emissions are projected under a non-intervention1 type of economic policy regime, called ``Business as usual'' (BAU).
Meeting the commitments made under the Kyoto Protocol requires careful plan-ning, prioritization, and eventual implementation of mitigation measures and poli-cies. In response to these commitments, the Government of Canada has instituted a process of developing a ``National Implementation Strategy'' for mitigating GHG emissions. Under this Program, a sum of $150 million has been allocated over 3 years for activities devoted to four themes: Technology Early Action Measures; Science, Impacts and Adaptation; Foundation Analysis, and, Public Outreach2. Under the Foundation Analysis theme, the Government has established 16 Issue Tables, one of which deals with the agriculture and agri-food sector.
The Agriculture and Agri-Food Climate Change Table (henceforth referred to as the Table) was set up to develop recommendations on various mitigation strategies and govemment/industry policies (and programs) that would lead to a reduction in the emissions of GHGs from agriculture, and thus help Canada meet its commit-ment under the Kyoto Protocol. Developing recommendations for various mitiga-tion strategies that can be undertaken by producers requires informamitiga-tion on several fronts. These include, although are not necessarily limited to, the following:
1. development of emission estimates from agricultural production for the two base periods Ð 1990 and 2010 under the BAU scenario;
2. identi®cation of mitigation strategies that can be implemented at the farm level which would lead to reductions in agriculturally induced GHG emissions; and
1 This refers to a set of conditions where no speci®c measure to reduce emissions of GHG is undertaken by the country.
3. a comparative analysis of the eectiveness of each strategy and/or measures in reducing emissions of GHGs from the agriculture and agri-food sector.
In addition, the Table was also expected to evaluate each mitigation strategy in terms of broad socioeconomic, health, and environmental impacts, as well as to assess various policy measures that may be required to ensure the adoption of the recommended mitigation strategy3.
1.2. Need for the study
In order to make recommendations for the selected mitigation strategies for GHG emission reduction, two types of tools are required: (1) tools for developing esti-mates of GHG emissions from the Agriculture and Agri-Food Sector (AAFS) in Canada at both national and regional levels; and (2) tools for testing the eective-ness of selected mitigation strategies. The ®rst set of tools requires information on the manner in which the adopted strategy would reduce GHG emissions in various regions of Canada. Such information could be obtained from scienti®c experiments under the assumed rate of adoption of the selected strategy.
In determining the emissions of GHGs from agriculture, two other considerations are important.
1. Farm level activities, although a major contributor of GHG emissions from agriculture, are related to other economic activities in the region as well as those outside the region. Two types of linkages that exist are: backward lin-kages of the agriculture sector, and forward linlin-kages. Backward linlin-kages are established between sectors when agriculture purchases its input needs from other sectors. The forward linkages, in turn, are established between agri-culture and those sectors that use its products for further value-added activ-ities. Let us illustrate the interrelationships between mitigation strategies and forward and backward linkages of agriculture. Let us assume that the selected mitigation measure is the adoption of proper soil nutrient management on farms. Such an adoption will lead to a change in the amount of nutrients added to various crops in various regions of Canada. Depending upon the nature of change, fertilizer input demand by farms would change. If the adjustment aects yields, it may also aect the relative pro®tability of various crops and may lead to a dierent production mix in dierent regions. Changes in the crop mix may also lead to impacts on livestock production. Depending upon the magnitude of such changes, this may further aect the competitiveness of processing industries, and thereby aect emissions from the food processing sub-sector. Such changes may be instrumental in bringing forth changes in regional trade, and may aect production of various agricultural products in other regions of Canada. Each of these changes would trigger an adjustment of GHG emissions in Canada.
2. Although most farmland is used for commercial agricultural pursuits, there are other land use activities from the farm unit that have implications for GHG emissions. This requires an examination of GHG emissions in a `whole farm' context.
The above two considerations raise the central question: ``How should the emis-sions from agriculture be measured, particularly in the context of prioritizing var-ious mitigation strategies in terms of their eectiveness for reducing GHG emissions?'' In this study, the suggested framework is that of the entire agriculture and agri-food system within a whole farm context. Adoption of a mitigation strat-egy by a producer may lead to other changes on the farm itself or at the regional level. Therefore, in addition to developing appropriate estimates of GHG emissions from agriculture, in the context of prioritizing various mitigation strategies, one should also resolve the issue related to changes in other farm and/or regional level activities resulting from the adoption of a given mitigation strategy.
2. Objectives and scope of the study
The major objective of this study is to develop a methodology for the estimation of GHG emissions from Canadian agriculture using a combined agriculture and agri-food sector approach and the whole farm context. This model is then used to illustrate the changes in GHG emissions for various mitigation strategies. Results are compared against model results where such linkages and whole farm context are not considered.
The objectives of the study are accomplished through the following sub-objectives:
1. to develop a conceptual model of accounting for GHG emissions from the AAFS that is appropriate in the context of developing recommendations for the National Implementation Strategy for Canada on Climate Change; 2. to estimate various components of the conceptualized model for two base
periods Ð 1990, and 2010 under the BAU scenario;
3. to illustrate the estimated changes in emissions levels from the 2010 BAU case for a simple scenario involving fertilizer use in various regions of Canada; and 4. to draw implications for using an appropriate methodology for prioritizing
GHG emission mitigation strategies for the Canadian AAFS.
The results presented here are part of the broader study of economic impacts of GHG mitigation strategies under consideration by the Table4. However, discussion in this study is limited to the examination of the GHG reduction potential for a selected mitigation scenario. Results of all possible scenarios that can be considered to meet Canadian agriculture's intended commitment under the Kyoto Protocol are not reported here, since this requires another study. Other impacts, such as
economic development impacts, ®scal impacts on various levels of governments, and regional development are also not included.
3. Model
3.1. Considerations involved
Proper determination of GHG emissions for the AAFS can be guided by three considerations: (1) the need to include all anthropogenic activities of the Canadian AAFS that lead to GHG emissions; (2) the need to include all other farmland uses besides agricultural pursuits, which is consistent with the `whole farm' approach; and (3) the need for consistency with the Intergovernmental Panel for Climate Change (IPCC) and Canada's Greenhouse Gas Inventory in accounting for and the aggregation of GHG emissions from various economic activities.
The ®rst consideration led to relating agricultural production to all major forward and backward linkages in the region. Two types of forward linkages were identi®ed for agriculture: (1) those within primary agriculture; and (2) those beyond primary agriculture. The former includes linkages between feed grain production and livestock production, while the latter includes links with transportation of agricultural pro-ducts beyond the farm gate (excluding that undertaken by producers), and processing activities induced by the availability of raw material for value added activities.
The second aspect of accounting for all agricultural GHG emissions required the inclusion of emissions from all farmlands and related activities within the agroeco-system level. Producers, in addition to cultivated lands, have uncultivated lands on farms. Some of these are waterlogged (farm potholes or wetlands), some are woo-dlots (bushes and other vegetation), while others are forested. These land use activ-ities either emit GHGs or sequester carbon.
The need for the third consideration was of paramount importance in the context of the Kyoto Protocol, since measurement of success is done in a framework pre-scribed by the IPCC (Houghton et al., 1997). The recommendations of the IPCC include a well-de®ned accounting framework for reporting inventories of GHG emissions. Details of this framework are provided in Houghton et al. (1997). Two stipulations in these guidelines are signi®cant for this study: (1) this framework suggested that accounting for emissions from non-energy sources be done separately from those from the energy-based inputs; and (2) soils as sinks of carbon are not recognized under the Protocol at this time. Thus, under this framework, agricultural soils as emitters of carbon dioxide (through the loss of soil carbon) are included in Canada's inventory of agricultural emissions, but when soils reach an equilibrium and beyond (i.e. becoming net sinks of carbon), carbon sequestration activities are not included5.
In order to maintain consistency with the IPCC guidelines, as well as to conduct the analysis incorporating the entire AAFS and the whole farm concept, estimated emissions from on-farm energy use and soil carbon were kept separate. This led to the model being more disaggregated in nature so as to allow for the accounting of GHG emissions from agriculture under the IPCC framework, as well as providing a more realistic picture of the total agricultural and agriculturally induced emissions for Canada.
3.2. Overview of the model
The model used in the study was designed to estimate emissions of three main GHGs associated with agriculture Ð carbon dioxide, methane, and nitrous oxide. This distinction was necessitated by the fact that each of these gases have a dierent global warming potential6. In order to ensure that the estimated emissions could be used for the purposes of examining mitigation strategies for meeting the Kyoto Protocol commitment, the model combined economic decision-making under a given set of physical and economic environments with emissions of GHGs. The resulting model was named the Canadian Economic and Emissions Model for Agriculture (CEEMA). The CEEMA being used in this study is a second generation model. The ®rst generation model CEEMA Version 1.0 is described in Kulsbreshtha et al. (1999). An overview of the model used in this study is shown in Fig. 1.
The CEEMA is organized into three sub-models (or blocks): resource allocation, science of GHG emissions, and estimation of total GHG emissions. The ®rst sub-model depicts regional resource allocations for crops and livestock, and is named the Canadian Regional Agriculture Sub-Model (CRAM). This sub-model was dis-aggregated using three criteria:
1. geographical location of agricultural activity; 2. type of enterprise (crop type or livestock type); and
3. technology of production (based on tillage systems, and crop rotations).
Agricultural activities were modeled on a provincial basis for all livestock produc-tion activities and for crop activities in regions outside the Prairies. However, crop production in each of the three Prairie provinces was disaggregated on a sub-pro-vincial level based on Census of Agriculture regions. Details on the number of regions for the crop and livestock production blocks are shown in Table A1 in the Appendix. Using the second criteria, all important crops were included in the model, as shown in Table A2. Various crop production regions had dierent mixtures of crops. Forages are important to the model since they provide an important linkage between crop and livestock production. Major livestock production included in the
study were: beef cattle, dairy cattle, hogs, poultry, and sheep and lambs7. Using the third criterion Ð technology of production, various crops in the three prairie pro-vinces and sub-regions were modeled using summerfallow and stubble (continuous cropping) rotations. Furthermore, wherever relevant, each of these production practices were speci®ed using one of three tillage systems: conventional tillage, minimum tillage, and no or zero tillage.
The second sub-model in CEEMA was the block where information on the sci-ence of GHG emissions was collected. This led to the development of emission coecients for the various crop and livestock activities speci®ed in the resource
Fig. 1. Schematic of the components of CEEMA.
allocation model. The order of priority in selecting a particular emission coecient should be regional, national (Canadian), and IPCC default values. In other words, if region-speci®c information was available, it should be used in the model. If such were not the case, national data would be selected and used for all regions. However, for most activities, regional or Canadian emission coecients still need to be esti-mated. The only information that was Canadian based was the soil carbon seques-tration coecients, which were obtained using the Century model calibrated for the region speci®c situations8. In all other cases, the model used the IPCC default values as emission coecients.
The third sub-model of CEEMA is the Greenhouse Gas Emissions Sub-Model (GHGEM). This model had the same level of disaggregation as the CRAM for regional, enterprise and technology of production. It used the information on emis-sion coecients (in sub-model 2) and the level of primary production activities from the resource allocation model to estimate GHG emissions.
In addition to GHG emissions induced by crop and livestock production, this sub-model included agroecosystem-based emissions. Total land base on farms was divi-ded into two types: cultivated and uncultivated. The cultivated land base was han-dled through crop production levels in the resource allocation sub-model. The latter category of land use included two types: (1) area under water (waterlogged) which results in emissions of methane; and (2) land covered by shelterbelts and other trees including agro-forestry, which results in the temporary sequestration of carbon. The term temporary is used to denote that the carbon sequestered by the trees is released into the atmosphere at the point of its ®nal use Ð either burnt as fuel, or left as a waste product (either in the municipal waste sites or individual areas). In both cases, this generates emissions of either carbon dioxide or methane into the atmosphere.
In addition to the three criteria for disaggregation, the GHGEM was further dis-aggregated with respect to processes associated with GHG emissions and the major GHGs. For each of the three GHGs, various processes associated with GHG emissions were grouped into eight modules, as shown in Fig. 2. These modules depict all backward and forward linkages of primary agricultural production. In total, 39 dierent processes in the agricultural and agri-food sector were hypothe-sized to be responsible for emissions from the sector. A complete list is presented in Table A3.
3.3. Model Requirements
The model required three major components: (1) development of baseline data for the 1990 and 2010 scenarios; (2) calibration of the resource allocation sub-model for the baseline situation(s); and (3) incorporation of emission coecients for the GHG emissions sub-model. In this study two baseline periods were used: 1990 and 2010. Their selection was based on the consideration that both of these are used for
measuring commitments under the Kyoto Protocol. The 1990 baseline is the basis against which to measure the required reduction in GHG emissions, while the 2010 BAU baseline is needed for measuring the performance of mitigation eorts by Canada.
The 1990 baseline data were obtained from the 1991 Census of Agriculture (Sta-tistics Canada, 1993). The 2010 BAU baseline was developed using results for AAFC's Medium Term Policy Baseline projections9to 2007, further extended to the
Fig. 2. Greenhouse gas emissions model for the Canadian Agriculture and Agri-Food Sector.
year 2010. The. calibration of the CRAM involved matching the baseline data for the two periods10 and was programmed using GAMS (see http://www.gams.com/ contacti.htm).
Estimation of the GHGEM was based on techniques referred to in Desjardins and Riznek (2000). Emissions were calculated for three modules: crop production, live-stock production, and the indirect agroecosystem. For the remaining modules, information was collected either from IPCC (Houghton et al., 1997) or Environment Canada (1997). Since energy use is the main source of emissions for non-primary agricultural activities, energy use data were obtained from the ICE and/or CIPEC Surveys11.
4. Results
4.1. Baseline (1990) emissions of GHG from agriculture
The Canadian AAFS contributes to GHG buildup through emissions of all three major gases Ð carbon dioxide, methane and nitrous oxide. However, for carbon dioxide, the sector is a minor contributor at the national level, which is not the case with the other two gases. For nitrous oxide emissions, AAFS's share is 59% of the total Canadian GHG emissions, and as such is the largest single source of such emissions (Table 1). For methane, agriculture is also a major contributor, since 36% of the total Canadian emissions are from the AAFS. Since agriculture is not a major user of energy, its share of total Canadian emissions of carbon dioxide is very small. The level of GHG emissions from the AAFS is either reported by the weight of each gas emitted, or by the weight in carbon dioxide equivalent of each gas. The latter is based on the respective 100-year global warming potential.12 In absolute quantities, the major gas that is emitted from the agroecosystem is carbon dioxide. The emissions are substantially larger than for methane and nitrous oxide (Table 1). Although the other two gases are emitted in relatively small quantities (Fig. 3a), a more realistic picture of the distribution of major GHG emissions is obtained after these emissions are converted into CO2-Eq. Here, as shown in Fig. 3b, nitrous oxide is the major GHG emitted by agriculture, followed by carbon dioxide, and methane. A little over a third of the total emissions (37%) from the AAFS are in the form of nitrous oxide. The main sources of such emissions are from fertilizer use, biological ®xation, crop residues and from manure handling systems and soil applications. Application of manure and fertilizer to soils also give rise to indirect sources of nitrous oxide. Much of the carbon dioxide emissions at the primary production level
10 More details on the CRAM are provided in Horner et al. (1992).
11 Details on these can be obtained from Statistics Canada (1997) and Natural Resources Canada (1997).
12 The 100-year global warming potential for methane is estimated at 21 times that of CO
are from the release of soil organic matter, and the use of energy for farm machinery and transportation. At the AAFS level, manufacturing of farm inputs is also an important source of carbon dioxide.
Canadian primary agricultural production is a net contributor of 65 megatonnes of GHGs (CO2-Eq) to the atmosphere. Activities induced by agriculture in non-farm sectors add another 25 megatonnes, making the total emissions from the AAFS at 90 megatonnes. Thus, direct agricultural production activities constitute 73% of the total emissions, while the remaining 27% by the nonagricultural sectors through activities that are induced by agricultural production related13.
Signi®cant dierences in the level and pattern of GHG emissions is noted for various regions of Canada. An east±west split of the total GHG emissions from agriculture is shown in Table 2. At the primary production level, western Canada contributes 68% of the total Canadian GHG emissions, while this share increases to 71% at the AAFS level. Major dierences in the regional distribution of emissions Table 1
Estimated emissions of greenhouse gases, by individual gas, Canada, 1990a
Source of emissions Level of emissions in kilotonnes
Carbon dioxide Methane Nitrous oxide
Crop production (including loss of soil carbon) 6033 0 36
Livestock production 0 977 32
Indirect crop and livestock production 0 0 31
On-farm fuel use (farm machinery, transportation, and stationary combustion)
Total primary agriculture 13,037 994 100
Farm input manufacturing 10,771 271 8
O-farm transportation and storage 1179 <1 <1
Food processing 4488 <1 <1
Total non-farm agriculturally induced activities 16,438 271 9
Total emissions for agriculture and agri-food sector 29,475 1265 109
Share of total Canadian emissions (%)c 6 36 59
a Numbers may not add due to rounding. Source: CEEMA 2.0.
b A positive number in each cell represents a source, i.e. emissions of greenhouse gases to the atmo-sphere, while a negative number represents a sequestration or sink activities. The latter category of emis-sions are not released into the atmosphere, and therefore, on a net basis, lead to reduced emisemis-sions of various greenhouse gases.
c Data for Canadian emissions, from Neizert et al.(1999).
are also noted. In the west, crop and livestock production-related emissions are both fairly large, whereas in eastern Canada, those from livestock production dominate.
4.2. Projected baseline (2010 BAU) emissions from agriculture
GHG emissions for the 2010 baseline under BAU assumptions were estimated by ®rst recalibrating the economic resource allocation sub-model (CRAM) for the future level of agricultural activities. The only GHG emissions coecients changed for this period (relative to those used for the 1990 baseline estimates) were those for soil carbon sequestration rates and fertilizer use. The soil carbon sequestration coecients are based on the Century model (Smith et al., 2000).
Baseline emission estimates for 1990 baseline, Canada
Emission module Emission level in kilotonnes in CO2-Eq greenhouse gases Proportion of total for Canada
Western Canada Eastern Canada Canada
Crop production (including loss of soil carbon) 14,203 3100 17,303 19
Livestock production 18,436 11,855 30,291 34
Indirect crop and livestock production 6229 3386 9615 11
On-farm transportation and stationary combustion
6198 1908 8106 9
Soil carbon sequestrationb 0
ÿ10 ÿ10 c
Agroecosystemb
ÿ656 377 ÿ279 c
Total primary agriculture 44,410 20,616 65026 73
Farm input manufacturing 16,995 1967 18,962 21
O-farm transportation and storage 1165 88 1253 1
Food processing 1200 3382 4582 5
Total non-farm agriculturally induced activities 19,360 5437 24,797 27
Total emissions for agriculture and agri-food sector 63,770 26,053 89,823 100
Regional share of emissions
Total primary agriculture 0.68 0.32 1.00 ±
Total agriculture and agri-food sector emissions 0.71 0.29 1.00 ±
a Source: CEEMA 2.0.
bA positive number in each cell represents a source, i.e. emissions of greenhouse gases to the atmosphere, while a negative number represents a seques-tration or sink activities. The latter category of emissions are not released into the atmosphere, and therefore, on a net basis, lead to reduced emissions of various greenhouse gases.
cLess than 1% of the total.
S.N.
Kulshreshth
a
et
al.
/
Agricultural
Systems
66
(2000)
145±166
entire AAFS is estimated to increase GHG emissions by almost 8 megatonnes of CO2-Eq, i.e. about 8% of the 1990 level.
5. Application of the model
Since emissions of nitrous oxide are a major component of agricultural GHGs, the scenario assumed an improvement in fertilizer use eciency in reducing GHG emissions from the AAFS. This scenario is based on improved eciency of nitro-genous fertilizers through better management practices (The Thomsen Corporation, 1999). This led to some reductions in application rates for some regions, particularly where the actual amount applied was deemed higher than that needed by crops.14
5.1. Description of scenarios
Currently it is thought that producers in certain regions (such as for corn pro-duction in Ontario) are applying fertilizer at higher rates than required. This Table 3
Increase in the emissions from the Agriculture and Agri-Food Sector in 2010 under Business as Usual situationa
Emission module 2010 Emissions for
Canada in kilotonnes of CO2-Eq greenhouse gases
Percent change in 2010 over 1990
Crop production (including loss of soil carbon) 15,416 ÿ10.9
Livestock production 35,608 +17.6
Indirect crop and livestock production 13,666 +42.1 On-farm transportation and stationary combustion 8134 +0.3 Soil carbon sequestrationb
O-farm transportation and storage 2007 +60.2
Food processing 7080 +54.5
Agriculturally induced non-farm activities emissions 30,700 +23.8
Total agriculture and agri-food emissions 97,326 +8.4
a Source: CEEMA 2.0.
b A positive number in each cell represents a source, i.e. emissions of greenhouse gases to the atmo-sphere, while a negative number represents a sequestration or sink activities. The latter category of emis-sions are not released into the atmosphere, and therefore, on a net basis, lead to reduced emisemis-sions of various greenhouse gases.
c Increase large due to a small denominator.
hypothesis is based on the opinions of agronomists and extension workers, and may result, at least in part, from a lack of knowledge on the part of producers with respect to the availability of nutrients in the soil at planting time. Similarly, in the Prairie provinces, producers apply a portion of the fertilizer in the fall, some of which is lost to the atmosphere as nitrous oxide during the spring thaw period. To improve upon this situation, two types of actions are suggested: (1) producers in non-Prairie regions are assumed to apply fertilizer based on soil test results; and (2) the fall application of fertilizer is eliminated in the Prairies, leading to reductions in GHG emissions. The amount of reduction in fertilizer for selected crops in various regions is shown in Table 4.
5.2. Direct eects of the scenario
The direct eects of the scenario included the following: (1) a change in the rate of fertilization, as well as the timing of application in the Prairies; (2) no eect on the yield was expected, since the stipulation is that the present level of fertilization is in excess of crop requirements; (3) soil testing will cost the producers $25 per ha (except in the Prairies where soil testing is already done); and (4) fertilizer costs in all regions are adjusted for reduction in quantity as well as through a change in the time of purchase (spring vs. fall).
One of most fundamental assumptions aecting the results of the analysis is the adoption rate of this practice. In this analysis, an optimistic adoption rate of 100% was used; in other words, all producers in the region were assumed to have adopted the suggested mitigation strategy.
5.3. Results of scenario: direct impacts
Direct results of the scenario stem from the reduced level of fertilizer application, which aects the cost of production for crops as well as nitrous oxide emissions from fertilizer application. Changes in the relative cost of production led to some changes
Table 4
Direct eects of study scenario Ð reduction in fertilizer application
Region Crops Reduction in fertilizer dose and/or timing
Corn ÿ50 kg/ha applied to 55%
of the area
ÿ0.55 kg of N2O /ha (where reduced)
in regional crop mix, which through inter-regional trade linkages resulted in further adjustments in the crop mix in a province. The results are summarized in Table 5. For western Canada, results from the resource allocation sub-model suggested a decrease in the area under silage corn and hay. However, for hay, the relative change was noted to be very small. For feedgrains and wheat, the eect was an increase in the area, although the relative changes were again very small (<1% of the 2010 base level). Another direct eect of the scenario is the reduction in the direct emissions of nitrous oxide. The rate at which these changes occur are shown in Table 4. This resulted in the reduction of total emissions in the region from fertilizer application.
5.4. Results of scenario: system level impacts
On account of the change in the fertilization level and its timing, total agricultural GHG emissions were estimated to be reduced by 403 kilotonnes in 2010 (Table 6). This amounts to a 6.8% reduction in the BAU baseline emissions level, and therefore, could be considered a signi®cant reduction. A relatively larger share of this reduction is in western Canada, partly because of the larger land base in crop production and the wider range of crops included in the scenario. These changes associated with the study scenario, although signi®cant, are only partial changes when one views the industry in terms of the total AAFS. Changes in the crop mix in one region lead to changes in other regions, and may aect livestock production in some provinces. However, estimated changes in provincial livestock production were very small. This could be explained by the substitution that might have occurred in the model between forage and feedgrains usage for livestock production purposes. Thus, very small changes in the quantity of GHG emissions from livestock production were noted.
In a systems context, one of the most signi®cant sources of GHG emission reductions for this scenario was the indirect emissions through atmospheric deposi-tion and nitrogen leaching. For Canada as a whole, reducdeposi-tion in these emissions are estimated at 540 kilotonnes per annum (Table 6). The third major change in the GHG emissions is through the economic activities induced by the direct changes. These primarily include manufacturing of fertilizer in various parts of Canada.
Table 5
Major change in the crop production activity under study scenario, 2010
Province/crop Change in thousand haa Percent change from 2010 Business as Usual
Western Canada
Wheat, barley and oats 25.83 0.15
Oilseeds 33.47 0.57
Once all other sources of emissions are accounted for, GHG reductions in western Canada are estimated at 1 megatonne of CO2-Eq, while those for eastern Canada are 0.2 megatonnes. This results in 1.2 megatonnes of GHG emissions reduced under the scenario. Relative to the 2010 BAU scenario emissions level, this reduc-tion is only 1.3% of the base level (Table 6).
5.5. Comparison of direct and systems approaches
The GHG emissions associated with fertilizer application could be labeled as direct emissions. A comparison of the results from this direct method with that using the entire AAFS under the scenario is provided in Table 7. Since all emissions other than from fertilizer application are excluded from the direct method, total reductions in emissions are grossly underestimated. In contrast, the systems method Table 6
Eect on greenhouse gas (GHG) emissions under study scenarios, 2010a
Region Emission source Change in
Western Canada Fertilizer application ÿ354 ÿ6.5
Other crop production ÿ15 ÿ0.3
Livestock production ±c ±
Indirect emissions ÿ427 ÿ4.2
Other farm activities +41 ±
Agri-induced non-farm activities ÿ238 ÿ1.0
All activities ÿ993 ÿ1.4
Eastern Canada Fertilizer application ÿ49 ÿ10.8
Other crop production ± ±
Livestock production ± ±
Indirect emissions ÿ113 ÿ3.2
Other farm activities ÿ4 ±
Agri-induced non-farm activities ÿ73 ÿ1.0
All activities ÿ239 ÿ0.9
Canada Fertilizer application ÿ403 ÿ6.8
Other crop production ÿ15 ÿ0.1
Livestock production ± ±
Indirect emissions ÿ540 ÿ3.9
Other farm activities +37 ±
Agri-induced non-farm activities ÿ311 ÿ0.3
All Activities ÿ1232 ÿ1.3
a Source: CEEMA Estimates.
b A negative sign indicates a reduction from the baseline scenario, whereas a positive indicates an increase.
takes into account all the changes in the agriculture and agri-food system, regardless of where these occur. In addition, these changes also include those incurred through changes in the enterprise mix on farms in various regions of Canada, although these were negligible in this study.
The relative performance of these methods suggests that at the primary agri-cultural production level, the direct estimation method underestimated changes in GHG emissions by 130%. The level of underestimation increases to 206% when emissions are measured at the AAFS level. Thus, at both the levels of aggregating GHG emissions, the direct method of emission estimation results in a signi®cant underestimation of emission reductions.
6. Summary and conclusions
In 1998, the Government of Canada agreed to reduce its 2010 GHG emissions to 6% below 1990 levels. In order to meet this commitment, analysis of the relative e-cacy of various mitigation measures for reducing these emissions is required. One approach to the evaluation of alternative strategies to reduce GHGs is to only look at the direct eects. Under this approach, only those changes that are associated in a direct manner to the selected scenario are recognized. The second alternative is to apply a systems framework, where in addition to direct emissions, all indirect and agriculturally induced emissions are accounted for. This study was undertaken to test the relative ecacy of a systems approach to measuring the changes in GHG emissions and compare the results against the more commonly used direct estimation method (where linkages among various activities farm or non-farm are not recognized).
This study indicates a substantial underestimation in GHG mitigation potential of a mitigation measure (practice) if the direct method of estimation is used. The Table 7
Comparison of results of study scenario, systems model and direct estimation, Canada, 2010
Source of emissions Greenhouse gas emissions in CO2-Eq kilotonnesa
Systems model Direct estimation
Fertilizer application ÿ402 ÿ402
Other farm level activities ÿ519 0
Primary agricultural emissions ÿ921 ÿ402
Agri-induced economic activities ÿ311 0
Total agriculture and agri-food system ÿ1232 ÿ402
Relative underestimation (direct estimates=100)
Primary agricultural emissions 230 100
Total agriculture and agri-food system 306 100
magnitude of this bias was estimated for a scenario where the target was to reduce emissions from fertilizer application. This included both a reduction in fertilization application rates, as well as the elimination of fall application in the Prairies. Under the direct method, changes in total Canadian GHG emissions were underestimated by about 130% at the primary agricultural production level. When all direct, indir-ect and induced activities under the scenario are accounted for, this underestimation bias increased to 206%.
This analysis demonstrates the need for a systems approach for prioritizing miti-gation measures for reducing GHG emissions. Since changes in agronomic and other cultural practices aect the economic returns from various enterprises, as well as create a second and third round eect on emission processes, a systems method need to be used in selecting GHG reduction strategies.
Acknowledgments
Authors would like to thank Dr. Bob MacGregor, Policy Branch, Agriculture and Agri-Food Canada (AAFC) for providing information on the scenario used for this study. In addition, we are grateful to Oliver Bussler, and Simon Weseen for their help in the development of the model, to Ravinderpal Gill and Carolyn Dauncey, of AAFC, for providing assistance in analyzing scenarios used in this study.
Appendix
Table A1
Regional disaggregation of the study model
Province Crop production regions Livestock production regions
British Columbia 1 1
Alberta 7 1
Saskatchewan 9 1
Manitoba 6 1
Ontario 1 1
Quebec 1 1
New Brunswick 1 1
Prince Edward Island I I
Nova Scotia 1 1
Newfoundland 1 1
Table A2
Major crops included in the study model
Crop type Crop activity
Greenhouse emissions processes in the model
Emission module Activity Carbon
Production of nitrogen ®xing crops X Loss of soil organic matter X
Fuel X X X
Livestock production Farm animals X
Animal excretions Ð manure X X
Animal excretions Ð grazing animals X Animal excretions Ð manure handling X
Indirect crop and
Direct agroecosystem Uptake by agricultural soils X
Waterlogged soils X
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