Climate Change and Agriculture in Manitoba

 

National and Provincial GHG Emissions

Environment Canada has been reporting GHG emissions since 1990 in compliance with the United Nations Framework Convention on Climate Change (UNFCCC), of which Canada is a signatory. Canada contributes approximately 1.5% of global GHG emissions and has one of the highest per capita emissions (about 22 tonnes of GHG per capita), largely due to the energy demands resulting from its climate, its size, and its resource-based economy (Environment Canada, 2010).

In 2008, agriculture accounted for 8% and 35% of total GHG emissions in Canada and Manitoba, respectively (Figure 2). Manitoba agriculture’s contribution of GHGs has increased 44% from 1990 to 2008, and this can be mainly attributed to expansion of the livestock sector (beef cattle and hogs) and increased use of synthetic nitrogen (N) fertilizers throughout this time frame (Environment Canada, 2010). The major GHG emissions from agriculture come in the form of carbon dioxide CO₂, CH₄, and N₂O from the following sources;

1. Carbon dioxide (CO₂) is produced from
   • The burning of fossil fuels for equipment and facilities, predominately
   • Losses in soil organic matter
2. Methane (CH₄) originates from
   • Livestock manure
   • Enteric fermentation of ruminant animals
3. Nitrous oxide (N₂O) is emitted from
   • Fertilizer usage, predominately synthetic N fertilizer
   • Decomposing crop residues
   • Manure on pasture and in storage

Figure 2.  Breakdown of Manitoba &  Canada's GHG Emissions by Sector for 2008

Source:  Environment Canada (2010). National Inventory Report, 1990-2008 - Greenhouse Gas Sources and Sinks in Canada

Contributors to Manitoba's greenhouse gas (GHG) emissions are different from other Canadian provinces in that the province does not have large industrial point source emitters.  In 2008, Manitoba constituted less than 3% of national GHG emissions and its agriculture sector contributes approximately 1% of the nation's GHG emissions. In 2008, the Agriculture sector was responsible for approximately 35% of the province's emissions, second to the Energy sector which contributed approximately 58% (Figure 2).

 

Sources of GHG from Manitoba Agriculture

The main contributors of GHG emissions from Manitoba agriculture are agricultural soils, enteric fermentation and manure management (Figure 3). From within these sectors the net GHG emissions from agricultural practices in Manitoba were roughly composed of 60% nitrous oxide (N₂O) (mainly from the use of nitrogen fertilizers on soils) and 40% methane (CH₄) (mainly from livestock enteric fermentation and manure management).

Figure 3.  Sources of GHG emissions from Manitoba agriculture

Source:  Environment Canada (2010). National Inventory Report, 1990-2008 - Greenhouse Gas Sources and Sinks in Canada

Nitrous oxide is the major GHG produced from agricultural soils which accounts for more than half of Manitoba agriculture's GHG emissions. These emissions can be further broken down into their specific sources from soil, including direct sources (50%), indirect sources (42%) and paddock, range or pasture sources contributing 50%, 42% and 8% of N₂O from agricultural soils respectively.

Direct sources of N₂O from soils include use of synthetic fertilizers (largest contributor), livestock manure applied as fertilizer, decomposing crop residue and soil organic matter decay that is disrupted by tillage, summerfallow, irrigation, and the cultivation of histosols (organic soils) (Environment Canada, 2010).

Indirect sources of N₂O from soils are those that come from movement of nitrogen from agricultural soils to surrounding soil or water. When either synthetic fertilizer or manure is applied to agricultural soils, some of the nitrogen is transported off-site through volatilization and subsequent redeposition or through leaching, erosion, and runoff. This nitrogen can then go through subsequent nitrification and denitrification to produce N₂O.

The smallest contributor of N₂O from agricultural soils is from manure excreted on pasture, range, and paddock from grazing animals. Nitrogen in the manure undergoes transformations, such as ammonification, nitrification, and denitrification that produce N₂O.

Nitrogen is a necessary component of soil and crop productivity; however, in some forms it also has negative effects to the atmosphere. Any nitrogen added to or existing in the soil is able to undergo denitrification via the nitrogen cycle (Figure 4).  N₂O emissions from agricultural soils are primarily due to synthetic and organic nitrogen fertilizers which not only contribute to agricultural GHG emissions, but also represent a loss of costly nitrogen fertilizers. Therefore there are both environmental and economic benefits for producers to optimize their nitrogen use efficiency by implementing beneficial management practices.

Figure 4.  The Nitrogen Cycle

Source: John Arthur Harrison, Ph.D. "The Nitrogen Cycle: Of Microbes and Men", Vision learning Vol. EAS-2 (4), 2003.

Enteric fermentation makes up the second largest proportion of GHG emissions in Manitoba agriculture (Figure 3). Methane is released from ruminant livestock as a by-product of digestive fermentation. Manitoba is home to approximately 1.2 million cattle and on average one cow produces 65 kilograms of CH₄ per day (Statistics Canada, 2009; Science & Technology Canada 2007). Significant research has been and continues to be conducted on developing mitigation strategies for enteric CH₄ production, however to date there is no long term solution to ruminant methanogenesis. However mitigation options are available for enteric fermentation such as providing high quality forages to ruminent livestock as it improves their feed efficiency and reduces CH₄ production.

Both N₂O and CH₄ are emitted as a result of manure management, which makes up the smallest portion of GHG contributions from agriculture in Manitoba (Figure 3). Depending on the manure storage system, the manure characteristics (animal source, solid versus liquid) and the quantity of manure, the amount and type of GHG produced will differ. Manure begins to decompose shortly after it is excreted. Should the conditions be anaerobic (without oxygen) then CH₄ is predominately produced, however if the manure is well aerated then N₂O will be produced. This also applies to manure storage facilities; those that are covered and are exposed to little oxygen will primarily produce CH₄ and little N₂O, while open air manure storage facilities will produce more N₂O and little CH₄ (Environment Canada, 2010).

A summary of GHG production and elimination for an agricultural setting (Figure 5) brings together all of the sources and sinks and allows for development of the best possible solutions for individual operations. Identifying the major on farm GHG emissions is the first step to mitigation. MAFRI offers numerous resources to help achieve individual reduction goals.

Figure 5.  Greenhouse gas sources and sinks within an agricultural system

Source: Farming Futures

 

Potential Climate Change Impacts for Agriculture

Agriculture is significant to Manitoba’s economy and is intrinsically sensitive to climate. There are advantages and disadvantages that may be experienced by agricultural crops and livestock as a result of climate change (Figure 6, Table 1). In North America, warmer conditions are projected to benefit food production, but strong regional differences are anticipated (Fields et al, 2007).

Figure 6.  Potential impacts of climate change on agricultural crops in Canada
	Click picture to enlarge
Source: Natural Resources Canada, Climate Change Impacts and Adaptation: A Canadian Perspective.

 

Table 1.  Potential impacts of climate change on agriculture's livestock in Canada
Projected Changes	Positive Impacts	Negative Impacts
Warmer Temperatures	Predominately in winter months: Lower feed requirements Increased survival of young Reduction in energy costs Expansion of pasture lands and grazing times	Predominately in summer months (heat waves): Death of livestock Reduced milk and meat production Reduced reproduction in dairy Suppression of appetite resulting in reduced weight gain Migration of livestock pests and pathogens northward
Increased frequency of extreme climatic events	not applicable	Drought – resulting in reduction in cattle stock to preserve pasture land Extreme rainfall/flooding Possibility of power outages Unpredictability
Enhanced atmospheric CO2	Increase growth rates in grasslands and pastures	Promotion of foreign species into grasslands, resulting in possible reduction of nutrient quality Possible decrease in nutrient concentration of desirable forage species
Source: Natural Resources Canada, Climate Change Impacts and Adaptation: A Canadian Perspective.

The agricultural sector’s vulnerability to climate change is dependent on the nature of climatic change, regional climatic sensitivity and the capacity to adapt to changes (Warren et al., 2004). Vulnerability to climatic change is multi-dimensional; it is determined by the sector’s response to interacting factors such as economic competition, farm management and cultivar selection, as well as indirect climatic stressors such as water availability and pest competition (Fields et al., 2007).

Although the benefits associated with warmer temperatures, longer growing seasons and increased CO₂ concentrations are anticipated to improve agricultural activities, there are other factors that may serve to counteract them. Reduced soil moisture, soil degradation, extreme climatic events and heightened presence of pests could exceed the benefits experienced (Warren et al., 2004). For benefits to be observed, practices will need to be chosen that can accommodate the current and changing climatic conditions.

 

For further information, contact your GO Representative.