Where are Canadian farmers most likely to generate multiple benefits from cover cropping?
An Article by Charlotte White, Jeff Liebert, Kushank Bajaj, Elena Bennett, and Navin Ramankutty
From small fruit and vegetable farms dotting the coasts to vast grain operations stretching across the Prairies, Canadian agriculture has an important role to play in climate change mitigation. Although farmers use an array of practices to grow crops in environmentally sustainable ways, agriculture still accounts for approximately 10% of the Canada’s greenhouse gas (GHG) emissions. Farmers, researchers, and policymakers have recognized this challenge as an opportunity: improving farm management has the potential to both lower GHG emissions and increase crop yields.
As part of the Government of Canada's Agricultural Climate Solutions initiative, the On-Farm Climate Action Fund is a $704.1-million program designed to support farmers in using beneficial management practices (BMPs) to increase carbon storage and reduce GHG emissions. Cover cropping, which involves growing plants for a range of environmental benefits (instead of for food, feed, fiber, or fuel), is one of the key BMPs recommended by the On-Farm Climate Action Fund. The multiple benefits that cover crops can provide include reducing soil erosion, increasing soil organic carbon, decreasing nitrogen losses, and improving weed suppression. Cover crops are typically planted after the main (cash) crop has been harvested and then terminated before the next primary crop is planted.
Cover crops can provide a variety of benefits, especially when soil, climate, and management decisions are carefully considered. (Left) Red clover, a perennial, leguminous cover crop, can biologically fix nitrogen and increase biodiversity by attracting pollinators with nectar and pollen. (Center) A vigorous, winter-hardy cereal rye cover crop has been flattened with a roller-crimper into a weed-suppressive mulch for no-till planted soybean. (Right) An intercropped cover crop mixture of annual ryegrass, hairy vetch, and crimson clover protects the soil from erosion, suppresses weeds, and adds biologically-fixed nitrogen between rows of corn.
Growing cover crops can yield numerous benefits, but it can also result in several drawbacks. For example, cover crops can increase soil organic carbon (by adding organic matter), which can improve soil health and boost crop yields. However, cover crops also consume soil moisture, potentially making the soil too dry for the main crop to thrive. This scenario could end up decreasing crop yields in non-irrigated cropping systems or during periods of low precipitation in rainfed agriculture.
Despite such trade-offs, agricultural policies often present cover cropping as universally beneficial, overlooking the context-specific nature of their management and performance. Given the urgency of the climate crisis, the Canadian government is investing substantial resources in climate change mitigation strategies, but in many cases, the allocation of resources to various incentive and cost-share programs favours the adoption and widespread implementation of cover crops. Notably, there is much less focus on the crucial step of monitoring the effectiveness of the practice or acknowledging the presence of trade-offs. The need for a more complete and place-based understanding of how cover crops are performing is particularly important when considering how diverse the environmental conditions and management approaches are across Canada.
To address these issues, we are conducting research through SOLUTIONSCAPES with a focus on two key questions:
What environmental conditions and management approaches are most important for predicting the benefits of cover cropping?
Where are Canadian farmers most likely to generate multiple benefits from cover cropping while minimizing trade-offs?
For the first question, we will compile data on cover cropping experiments from across Canada and other temperate regions around the world for use in predictive models. Using machine learning, which is a powerful tool for pattern-recognition and prediction, we will identify the key soil, climate, and management factors associated with cover cropping benefits. For the second question, spatial techniques will be combined with the results from the machine learning models to create maps that indicate where in Canada farmers will be most likely to achieve multiple benefits from growing cover crops. Different management scenarios will be included in the spatial analyses to accommodate the influence that management decisions have on cover cropping outcomes.
By gaining a deeper understanding of the context-specific performance and potential trade-offs of cover cropping, we hope that this research will inform Canada’s agricultural and climate policy. With a more targeted approach, resources can be put towards initiatives that will better support farmers and advance Canada’s climate action goals.