Carbon sequestration is an important part of reducing net GHG emissions. It offsets GHG emissions by transferring carbon dioxide (CO2) from the atmosphere into carbon storage in plants through the process of photosynthesis. Much of this carbon is then transferred from the plants into the soil when the plant residues break down instead of being released back into the atmosphere
The improvement of carbon sequestration in agriculture is achieved by increased input of carbon into the soil and decreased soil disturbance. Two on-farm management practices contribute to these objectives: the adoption of zero-tillage and the removal of summerfallow from crop rotations. Since the early 1990s, the adoption of zero-tillage and the complementary reduction of summerfallow has spread rapidly in Western Canada. Between 1991-2016, the number of Canadian acres with zero-tillage management increased by 900%, from 4.8 million acres to 48.2 million. In the Prairie Provinces specifically, the number of acres managed with zero-tillage increased from 4.5 million acres to 45.2 million over this period. At the same time, the number of acres under summerfallow management decreased by 88% between 1991-2016, from 19.57 million acres to 2.21 million.
Older research suggested that carbon equilibrium would be achieved 20-25 years after the adoption of sustainable management practices, meaning that soils become carbon saturated and unlikely to continue to sequester carbon. However, recent research by the Saskatchewan Soil Conservation Association (SSCA)suggests that soil carbon is still increasing even 30 years after the adoption of sustainable on-farm management practices. Thus, improved carbon sequestration remains an important contributor to Canada’s climate change goals.
In 2018, Smyth and Awada released a report quantifying Saskatchewan’s net GHG emissions. As part of the analysis, they estimated the change in Saskatchewan carbon sequestration due to the adoption of zero-tillage and removal of summerfallow. Their results can be seen in the figure below, with the red line representing a situation where soil carbon saturation is reached after 25 years, and the blue line representing infinite carbon storage.