Results for tag "sustainability"

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Canada’s Environmental Scorecard on Agriculture

im McCabe / Photo courtesy of USDA Natural Resources Conservation Service.

With nearly sixty-five million hectares of land for crops and livestock production, Canada is among the largest agricultural sectors in the world. Agriculture and Agri-Food Canada (AAFC) has recently published their fourth Agri-Environmental Indicators report providing an insightful look into a number of sustainability metrics used for measuring the environmental trends (1981 to 2011) in Canada’s agricultural sector. In this post we’ll take a glance at the sustainability trends of Canada’s agricultural sector over the past twenty years through four nation-wide environmental indices.
Trends for the four Compound Sustainability Indices that are currently applied in AAFC's Agri-Environmental Indicator reporting

Trends for the four Compound Sustainability Indices that are currently applied in AAFC’s Agri-Environmental Indicator reporting (adapted from AAFC’s report)

It should be kept in mind that AAFC’s science based agri-environmental indicators as presented above are a nation-wide summary of environmental performance covering a range of different environmental indicators across Canada’s diverse regions and commodity mixes. You’re urged to dig deeper into the different indices and region-specific results by following this link.


The overall trend from 1981 to 2011 for biodiversity shows steady and consistent improvements across Canada, moving from a ‘Poor’ status in 1981, to a ‘Moderate’ status in 2011, as depicted by the Biodiversity Compound Index above. This compound performance index is a weighted average of the Soil Cover and Wildlife Habitat Capacity performance indices.1 As such, it is a highly  statistical snapshot of these two variables both in terms of current state and over time.2 The improvements are largely due to changes in tillage practices reflected in the Soil Cover Indicator in particular. The use of reduced tillage and no-till has been increasing continuously since the early 1990s, as a means to reduce fuel costs and improve soil health. Between 2006 and 2011, the total area of agricultural land under intensive tillage declined by 30.9%. In 2011, no-till land management was applied on more than 50% of all agricultural areas prepared for seeding in Canada (Statistics Canada, 20116). This reduction in tillage, coupled with the decreased use of summerfallow, resulted in a national-scale improvement in average levels of soil cover in Canada. From 1981 to 2011, average levels of soil cover in Canada increased by 7.6%.
From 1986 to 1996, wildlife habitat capacity (WHC) was relatively stable; however from 1996 to 2011 there was an overall decline in WHC at the national scale, despite the drop in summerfallow (which offers limited capacity for wildlife) and rise in soil cover. The decline in WHC was primarily due to the intensification of farming as well as the loss of natural and semi-natural land, mainly resulting from the shift away from pasture and forage production to annual cropping, especially in Eastern Canada.

Soil Quality

Considering various aspects of soil quality together, as illustrated in the Soil Quality Compound Index above, agriculture’s environmental performance has a ‘Good’ status, and has significantly improved over the 30-year period preceding 2011. This compound index is a weighted3 average of the performance indices reported for the Soil Erosion, Soil Organic Carbon and Soil Salinization Indicators, plus findings from the Trace Elements Indicator (extrapolated from previous years, not reported in this publication).4 As such it is a highly generalized statistical snapshot of soil health, both in terms of current state and over time.
Improvements to the Soil Quality Compound Index can be directly attributed to improvements in land management practices, such as increased adoption of reduced tillage and no-till practices, and the reduction in area under summerfallow. The improved performance was driven by the Prairie Provinces where cultivated agriculture is extensive and is dominated by cereals and oilseeds. This agricultural region is most amenable to reduced-till and no-till practices. Increased soil cover resulting from these has led to a significant increase in soil organic matter. The reduction in tillage has also led to a reduction in soil erosion risk, notably tillage erosion, which has historically accounted for the majority of erosion losses (followed by wind and then water). The extensive reduction in area of summerfallow has also improved soil health, leading to a reduction in soil erosion – particularly from wind and water; and has also reduced salinization risk.
Generally, higher rainfall in Ontario, Quebec and the Atlantic Provinces compared to the Prairies supports more intensive agriculture and a different mix of crops. These regions have seen a shift away from pasture and forage production, following the decline in cattle production in 2006, towards row crops which offer less soil protection. However, as the majority of agricultural land is sited in the Prairies, where soil health is improving, the national picture is also one of improvement for soil health.

Water Quality

Considering various aspects of risks to water quality together ,5 agriculture’s environmental performance currently has a ‘Good’ status. It does however represent an overall decline from a desired state in 1981. This overall declining performance is mirrored by the individual indicator performance indices, which moved from ‘Desired’ status in 1981 to ‘Good’ status in 2011, with the exception of the Phosphorus Indicator, which moved from ‘Desired’ status to ‘Moderate’ status. The deterioration in the index can be attributed to increased application of nutrients (N and P) as fertilizer and manure as well as an increased use of pesticides across Canada.
The declining agri-environmental performance was observed in all regions of the country. In the case of nitrogen, the levels of residual soil nitrogen have increased steadily as inputs from fertilizer and manure in particular have increased at a faster rate than outputs from crop harvests, gaseous losses and leaching. This soil nitrogen is most readily available in the form of water-soluble nitrates, which are at risk of leaching to ground water and, where fields are tile-drained, into drainage water, which can then be directed into ditches, streams and rivers.
Despite this increasing risk, the Nitrogen indicator remains in the ‘Desired’ category. In the case of phosphorus, performance has declined quite dramatically from ‘Desired’ in 1981 to 1991, dipping to ‘Good’ in 1996, recovering to ‘Desired’ in 2001 and declining since that time. This report is the first time this indicator has been classified as ‘Moderate’, reflecting a combination of phosphorus source and transport. Increased surpluses in soil-phosphorus in all regions reflect national increases in fertilizer and manure application as well as increased concentration of livestock. Added to this increased source is the much higher than average runoff in 2011, following a very wet spring throughout the Prairies. This increased runoff increased risk by flushing much of the built-up soil phosphorus into surface waters.
While overall livestock numbers have decreased on a national scale, there is a growing trend towards larger operations, with higher concentrations of animals. A consequence of this increase is that on-farm manure capacity can grow to exceed the capacity of surrounding land to use it as fertilizer, sometimes leading to higher application rates. As a result, the Coliforms Index has deteriorated from ‘Desired’ in all preceding years, to ‘Good’ in 2011. In the case of pesticides, the risk of water contamination has increased on about 50% of cropland over the past 30 years. The index has deteriorated from ‘Desired’ in all preceding years to ‘Good’ in 2011. The highest risk increases occurred in the Prairies between 2006 and 2011 where the area treated by fungicides doubled. This increase, as well as increases in herbicide use, can be attributed to the switch to reduced tillage and no-till which necessitates the use of pesticides to control weeds and diseases (reduced tillage systems are more susceptible to fungal diseases). The increased risk can also be explained by a shift away from pasture and forage to cropping systems that require more pesticide inputs and, to a lesser extent to wetter weather in the Maritime Region in 2010.
Increased efforts are required throughout Canada to minimize the risk of nutrient, pesticide and coliform movement to surface water bodies and leaching beyond the rooting depth of vegetation. This is particularly so in higher rainfall areas of the country. This risk can be further reduced through practices such as regular soil testing and better matching agricultural inputs application to field conditions. Practices that mitigate surface runoff, such as establishing riparian buffer strips, winter cover crops, maintenance of surface residue, etc. will also contribute to a reduced risk to water quality.

Air Quality

Considering various agricultural atmospheric emissions together,6 agriculture’s environmental performance in air quality is ‘Good’, having been relatively stable between 1981 and 2006, and then significantly improving to 2011. This improvement is mirrored by improvements in all the individual performance indices within this theme.
Improvements in land management practices such as increased adoption of conservation and no-till practices, reduced use of summerfallow, and increased forage and permanent cover crops were primarily responsible for the improved agri-environmental performance for air quality. Adoption of these management practices, particularly in the Prairies, led to soils becoming a net sink for atmospheric carbon, which means more carbon is being sequestered in soil than is being emitted, leading to a reduction in overall greenhouse gas (GHG) emissions. The same practices have led to improvements in particulate matter (PM) emissions over the period of study. A decrease in numbers of livestock across the country between 2006 and 2011 is the primary reason for the improvements in the ammonia emissions performance index, which now sits at just above 1996 levels.
Land management practices that favour sequestration of carbon in the soil, such as reduced tillage and residue management practices to maintain soil cover, need to be continued and expanded in order to maintain and increase the amount of carbon dioxide removed from the atmosphere and stored in the soil. Similar practices that reduce the number of field operations and protect the soil surface from wind erosion are effective in minimizing PM emissions. Improved animal feeding strategies and more efficient use of nitrogen in agriculture are examples of beneficial management practices (BMPs) that can be used to mitigate emissions of methane, ammonia and nitrous oxide.
In future posts, I’ll delve deeper into each of these environmental indicators to better understand key regional differences, and reasons for poor or desirable environmental performance as well as take a closer look at some promising current and prospective best management practices available for farmers to implement.

1. All national “core” indicators, to include Soil Cover and Wildlife Habitat Capacity on Farmland have a weighted value of 1.
2. More information on how performance indices are calculated can be found in Chapter 2 “Assessing the Environmental Sustainability of the Agri-Food Sector.”
3. All national “core” indicators, to include Soil Erosion, Soil Organic Carbon and Trace Elements have a weighted value of 1. In the case of Soil Salinization Indicator, which covers only the Prairie extent, its weighting is reduced to 0.81 to reflect the percentage of farmland area under coverage.
4. The Risk of Soil Contamination by Trace Elements Indicator was developed for the 1981 and 2006 Census years only and therefore does not have a Chapter designated to it in this publication. However, since these trace element values are not likely to change significantly from year to year at the scale of analysis used in this report, they have not been recalculated for 2011. Instead, the 2006 trace element values were extrapolated for use in the 2011 year, and were included in the calculation for the overall Soil Quality compound index.
5. The Water Quality Agri-Environmental Performance Index combines indices for water contamination by nitrogen (N), phosphorus (P), coliforms and pesticides.
6. The Air Quality Agri-Environmental Performance Index combines indices for greenhouse gases (GHGs), particulate matter (PM) and ammonia emissions from agriculture.



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How Clean Would Site-C Hydro Power Be?

As most citizens of British Columbia realize by now, the Site-C hydro power project along the Peace River has been approved by both the Federal and the Provincial Government. After reading the aforementioned approvals I noticed the project was always referred to as being the “Clean Energy Project”. This notion of clean they refer to is commonly understood as being due to the operation phase of hydro power not requiring any solid fuel substrate to convert into electricity and therefore does not emit undesired air emissions during energy conversion such as particulate matter, nitrogen oxides, sulphur dioxide, dioxins and heavy metals. The Site-C project’s level of ‘cleanness’ can also be referred to in terms of life cycle greenhouse gas emissions which is an important metric when comparing several power production alternatives. I became very curious to understand, how ‘GHG-clean’ would the Site-C project likely be.

GHG Intensity of Site-C Hydro Power as Calculated

Well, it turns out Site-C hydro power would likely be quite clean. Upon reviewing the ‘Report of the Joint Review Panel Site C Clean Energy Project‘ information was limited on how BC Hydro undertook the life cycle greenhouse gas (GHG) analysis of the project. After a little more digging I found the original technical report for which the life cycle GHG intensity of 10.5 grams CO2eq. per kWh (gCO2eq./kWh) is based on. At face value British Columbians should  feel fairly good about this low GHG intensity factor considering natural gas and coal power have GHG intensity factors that typically fall in the range of 350-550 and 900-1200 gCO2eq./kWh, respectively. The IPCC Special Report on Renewable Energy provides the following concise figure explaining life cycle GHG intensity of different power sources as depicted below:


Figure 1: Life Cycle GHG Intensity Ranges for Several Power sources (units: gCO2eq./kWh) (source)


Despite the Site-C hydro power system likely having a low GHG intensity it is a worthwhile exercise to gain at least a simplified understanding of how this 10.5 gCO2eq./kWh factor was derived. The GHG technical report split GHG project emissions into two main categories: hydro power reservoir construction and operation. With a series of sensitivity analyses included, the likely annual average emissions from these two activities were estimated to be 124,600 tonne (t) CO2eq. per year due during the construction phase (for 8 years) and 43,400 tCO2eq. (net) per year during the operation phase (for 100 years). Since the capacity of Site-C is designed to be 1100 Mega-Watts (MW) and the average annual energy generation is expected to be about 5100 Giga-Watt-hrs (GWh) we can calculate the report’s estimated likely GHG intensity factor of 10.5 gCO2eq./kWh:  


10.5 gCO2eq./kWh = (43,400 tCO2eq./yr + 124,600 tCO2eq./yr*8yr/100yr)/(5100 GWh/yr*106kWh/GWh)*106g/tonne


The GHG emissions during the 8 year construction period were due to material requirements, fuel combustion and electricity demand and these emissions contributed 1.95 gCO2eq./kWh to this 10.5 value. The remainder and majority of the GHG intensity (8.5 gCO2eq./kWh) was due to the net GHG emissions that stemmed from direct land use change (emissions that occur during the operation phase). Let’s explore this part of the GHG intensity factor next. 

Net GHG emissions from Land Use Change

The Site-C reservoir requires a significant area to be permanently inundated. Stretching 83 km along the Peace River the surface of the reservoir is expected to span an area of 9,330 hectares (ha) and this would require the flooding of 6,345 ha of land. The figure below shows the land-type breakdown of the land area that would be slated for inundation. 


Figure 2: Breakdown of the land-types to be flooded as a result of Site-C Hydro Project (source)


As shown above the majority of land inundated would be sparse trees while about 570 ha of land to be flooded is considered as cultivated agricultural land. The idea of net GHG emissions attributed to the Site-C project due to inundation was calculated by taking the difference in GHG emissions/sources between the inundation area as it is today and the inundation area upon project completion where operational GHG emissions are estimated across a 100 year operational time horizon. In terms of current land productivity the technical report assumed that apart from the cultivated land there were also livestock/grazing activities considered where a current estimate for beef (1,000 head) and dairy cattle (300 head), swine (300 head), horses (150 head) and bison (300 head) was made. GHG emissions from current activities (i.e. farming) upon areas planned for flooding were then estimated and subtracted from the operational GHG emissions expected from the reservoir over the 100 year life time. The figure below illustrates the possible GHG emission sources from a typical hydro reservoir.


Figure 3: A schematic of the various GHG sinks and sources in a hydro reservoir system (source)


As illustrated in the figure above there are a series of complex mechanisms that need to be considered when estimating GHG emissions and sources. A recent study by Professor Edgar Hertwich attempts to integrate these emissions into a life cycle assessment perspective. Here Prof. Hertwich reviewed and analyzed the generation of greenhouse gas emissions from reservoirs for the purpose of technology assessment, relating established emission measurements to hydro power generation. What he found was the global average emissions from reservoir hydro power are estimated to be around 85 gCO2/kWh and 3 gCH4/kWh. Despite this relatively high average in net GHG emissions (equates to 148 gCO2eq./kWh) the study’s recommended numbers for boreal reservoirs (0.97 kg CO2/m2/yr and 40 g CH4/m2/yr) leads to a GHG intensity factor of 21 gCO2eq./kWh.

These factors suggest that the likely GHG intensity assumed for the Site-C hydro power system might be underestimated though the level of uncertainty in calculating net GHG emissions from a reservoir makes it difficult to say who is more correct. At first glance, I think the Site-C GHG technical report undertook a thorough GIS based site-specific analysis utilizing as much localized data as possible and their likely GHG intensity factor of 10.5 gCO2eq./kWh is probably more accurate because of the details that went into this technical report. All in all, Prof. Hertwich highlighted the importance of this emission source, the major limitations of trying to measure these emissions and the high level of uncertainty involved in these calculations. He also found that the power density (plant capacity divided by reservoir area) of the hydro power plant has a strong correlation with reservoir GHG intensity. He cautioned that any hydro reservoir plants with a power density of around 4 W/m2 or less should be avoided. It turns out that the Site-C hydro power plant would have a power density of 20 W/m2 which is well above this CDM project eligibility boundary that Prof. Hertwich generally agreed with.

Followup Questions

Although I do think the Site-C hydro power system would be relatively clean in terms of GHG intensity I do think it is only fair to explore the alternatives and to better understand their associated GHG intensities. For instance, the Canadian Geothermal Energy Association proposed a more cost effective geothermal power alternative and Clean Energy BC proposed a more affordable small-to-medium scale renewables alternative as well. While these projects suggest less cost to BC tax payers, could these projects also equate to less GHG intensity? Another question on my mind is what about the 570 ha of cultivated land and the additional land required for grazing and livestock activities currently taking place on the to be inundated Site-C project land? In a typical LCA study involving presently productive land use change the GHG emissions due to indirect land use change should also be considered in the GHG intensity calculations. In subsequent blog posts I will explore these followup questions. Please stay tuned.