Exploring Herbicide-Tolerant Canola's Contribution to the Carbon Sequestered in Saskatchewan Agricultural Soils Over the Last Twenty-Five Years
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In recent decades, Saskatchewan farmers have been progressively shifting towards practices which improve their on-farm sustainability. The adoption of two practices in particular, conservation tillage and the removal of summerfallow, improve soil carbon sequestration by minimizing soil disturbance and increasing crop residue levels. The introduction of numerous agricultural innovations and technologies facilitated the adoption of these management changes. One particular technology, herbicide-tolerant (HT) crops, played an important role in this shift by providing farmers with more efficient and cost-effective in-crop weed control. In Saskatchewan, the most widely planted HT crop is canola. This thesis quantifies the change in soil organic carbon (SOC) levels in Saskatchewan agricultural soils resulting from changes in tillage, summerfallow, and crop rotation practices following the introduction of HT canola in 1995. Data for the analysis is gathered through a survey of 100 Saskatchewan farmers’ land management practices both prior to 1995 and in their most recent crop rotations. The change in SOC between the two time periods is quantified using a carbon accounting framework adapted from the Prairie Crop Energy Model. The framework quantifies changes in SOC levels by aggregating the effects of changes in famers’ tillage and summerfallow practices, crop type, crop yield, and residue removal techniques. Carbon coefficients used in the model were developed for Canada’s national greenhouse gas inventory reporting. Farmers’ attribution of various technologies to their changes in management practices, including HT crops and glyphosate, are also assessed using survey results. On average, participants assign a value of 9.1 out of 10 for glyphosate’s contribution to reductions in tillage and summerfallow practices, and a value of 7.3 out of 10 for HT canola. An economic valuation is applied to the change in SOC using three pricing scenarios to create upper- and lower-bounds on the estimate: a carbon marketplace, a carbon tax, and the social cost of carbon. The estimated value for the increase in annual SOC gains on Saskatchewan’s cropland is approximately $166 - $384 million from reductions in tillage practices and $459 million - $1.059 billion from reductions in summerfallow practices. The objective of this study is to provide information to industry, policy makers, and the public of farm-level impacts of management changes relating to SOC gains. This information will help support agricultural representation in discussions regarding environmental and agricultural policy.
DegreeMaster of Science (M.Sc.)
DepartmentAgricultural and Resource Economics
SupervisorSmyth, Stuart J
CommitteePhillips, Peter W. B.; Kerr, William A.; Hesseln, Hayley; Brewin, Derek G.
Copyright DateJune 2021