Agricultural Sector


Ontario Agriculture – Mitigation or reducing emissions to reduce the effects of climate change.

This section begins with a look at the global concepts for agriculture. Ontario practices are later in this section.

Source: IPCC 2001. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Changes [Houghton, J.T., et al. (eds.)]. Cambridge University Press, Cambridge, UK. P 188

In the above figure agriculture fits into the green print!

One way to reduce the effects of emissions, or mitigate the effects of climate change, is to improve natural carbon storage or “carbon sinks”. The process of photosynthesis uses carbon dioxide as a raw material. Photosynthesis locks up CO2 in bigger molecules such as glucose for energy and cellulose for cell walls a natural carbon sink.

“Carbon sources” are processes that release carbon to the atmosphere such as the respiration of all living organisms and the burning of fossil fuels.

Almost all sources and sinks in agricultural soils are human in origin. Cultivating the soil exposes it and adds more carbon dioxide to the atmosphere. This may be because of exposure increases the rate of respiration and the rate of decay. The number of soil organisms could also increase. These sources are poorly understood.

Low or no tillage cultivation ie ploughing, harrowing etc lowers the amount of carbon dioxide released – acting as a carbon sink. There is a trend in Ontario and across Canada towards no tillage for economic reasons such as to save fuel, fertilizer and time and well as maintaining or improving crop yields. Projections suggest that our soils will soon be net sinks.

The graph below reflects the changes in megatonnes of carbon dioxide released through Canadian agriculture over the last 40 years. Projections for 2010 are included.

Source: National Climate Change Process Sinks Table Report, 1999, p 94.

1. When was the amount of C02 released per year greatly reduced? What was happening in the world at this time?
2. What other factors are helping agricultural soils become a net carbon sink?

New technologies such as use of GPS on specific field machinery for fertilizer application and computer designed feeding programs for each diary cow are only two of the many new developments that save use of materials and energy in Ontario in 2004.

Programs dealing with marginal land, woodlots, riparian strips, sloughs and well-head protection are helping to make land use more responsive to climate change as well as reduce the use of fossil fuels. Ecological gifts and conservation easements, public parkland are all ways that individual owners can work together with governments, agencies.

The cost of transportation of food may be a factor in the future as farmers chose their specialized crops for the specialized markets and the distance from the farm gate.

One example of changes in land use is those that have already occurred in some of the best crop land in Ontario. These changes are due to the latitude and soil type. The units used are Corn Heat Units (CHU). CHU use temperature in degrees Celsius and time.

The accumulated value is based on the following conditions:

  • Start-up of corn growing season: where the mean daily temperature is> 12.8 oC for three consecutive days during the period May 11 to July 31.
  • End of the season: the first occurrence when the minimum daily temperature drops below -2.0 oC during the period August 1 to October 15.

The map below shows the contour lines for similar CHU values in southwestern Ontario.

Source: Watson and MacIver (1995) Integrated Assessment Mapping Project www.utoronto/imap

ACTIVITY 2 Questions
1. This southernmost part of Ontario, of Canada. What is the range of latitude shown?
2. Check the area shown against the land cover and CHU map re: agricultural use. Does this area go north beyond the 2900CHU line shown there?
3. Check with the map showing loss of original wetland area below. What does correlating these maps explain?

ACTIVITY 3 Research
1. Check the correlation of the hardiness zone map used by gardeners and foresters.
2. Check the implications of climate change impacts for agriculture, natural vegetation and Ontario’s economy.

On the map below the percent of lost wetland is shown in relationship to the CHU contour lines. These indicate indirectly the number of days needed to grow crops.

Source: Don MacIver Integrated Assessment Mapping Project

1. What is the relationship between the percentage of wetland lost and the CHU?
2. Check the latitude of this area on a map of Ontario and relate this to the CHU and Environment Canada’s Hardiness Zone map.

Species at risk habitat restoration programs work with landowners and farmers to bring back natural environments can be looked upon as mitigating the effects of climate change. Habitat restoration conserves fossil fuels, emits fewer greenhouse gases and releases less heat. However restoration of habit also changes the albedo effect of the land. See Albedo in section 3. See the Forestry section

New crops are being selected to match the reduced water supply and higher temperatures of changing climates. New drainage ditch management and low or no tillage practices support these new conditions.

Source: Don MacIver Integrated Assessment Mapping Project

1. The map above shows the loss of forest cover and increased farm land. Account for this change.
2. How will these changes affect the amount of carbon dioxide released annually?
3. Check the Ontario Federation of Agriculture and Ministry of Agriculture for other web sites. Look for new developments and new methods that can be considered mitigation or ways to reduce emissions.

ACTIVITY 6 Research
What other parts of southern Ontario are changing the percentage of forest cover?

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