November 11, 2002
Mr. Solomon points out that Canada’s greenhouse gas emissions contributed by the agriculture sector is about 10%. What he neglects to indicate is that, in fact, the agriculture sector will address 20% of Canada’s target emissions now that agricultural soils are recognized as carbon sinks.
Mr. Solomon also describes “large, mechanized farms, whose crude tillers deplete carbon from topsoil.” It is obvious that he is unaware that several years ago, many prairie farmers adopted a production management system, called direct seeding or zero tillage, that enables farmers to seed directly into the previous crop’s standing stubble. In this management system, the only time the soil is disturbed is at the time of seeding, drastically reducing greenhouse gas emissions. Sound science has proven that soil carbon (organic matter) actually increases in this system. The Prairie Soil Carbon Balance Project, conducted by Agriculture and Agri-Food Canada, measured the change in soil carbon over a three-year period for 150 commercial farm fields that had just been converted to direct seeding. In that time, there were statistically significant increases in their carbon content.
In direct seeding or zero tillage systems, farmers eliminate tillage-based black fallow from their rotations. Leguminous crops such as pulses and short-term forages are often added to the rotation. Another farming practice that serves to maintain a healthy environment is the establishment of permanent forages on marginal cropland. Perennial forage plants remove large amounts of carbon dioxide from the atmosphere. Once established, forages are left in stands for several years resulting in an accumulation of soil organic carbon. Perennial forages also stabilize fragile, marginal soils, leaving them less susceptible to the forces of wind and water erosion.
A second benefit to a direct seeding or zero tillage system is the reduction in the use of fossil fuels. As fewer tillage operations are required, fossil fuel usage declines. Many farmers report a drop in total tractor hours by as much as 60%, a dramatic reduction in the farm’s fuel consumption. In fact, the capture of one tonne of carbon dioxide in the soil is the equivalent of removing the emissions created by burning 725 litres of fuel. This combination of reduced fuel usage and removal and storage of carbon dioxide in soils makes a major contribution in reducing the nation’s emissions inventory.
Don Horsman, president
and Blair McClinton, PAg, executive manager
Saskatchewan Soil Conservation Association