Internship Experience with Soil Conservation Council of Canada and Compost Council of Canada
By Rebecca Johnson, MSc Graduate from the University of Guelph
Carbon sequestration has been a hot topic recently, with companies investing in reforestation with worldwide efforts to stop rapid deforestation in tropical rainforests. Even though 550 gigatons of planetary carbon is stored as vegetation, there are other ways to offset emissions and may take a shorter period of time. Soils contain 18% (2300 gigatons) of all terrestrial carbon and are highly degraded in many regions (1). This means that soils are uniquely suited for carbon sequestration since they can store carbon long-term and have great potential to store large amounts of carbon.
As part of my internship project with Soil Conservation Council of Canada and Compost Canada, I looked to find just how much potential carbon could be sequestered in Canada’s managed soils. Canada manages approximately 68.9 Mha of agricultural soils, with 59% of land in crops, 30% in unmanaged or managed pastures and the rest split between woodlands, wetlands and fallow land (2). Therefore, the potential area for soil carbon sequestration could be as high as 46 Mha of managed agricultural soils. If optimal agricultural practices are used on these managed soils, carbon can be stored long-term as a nature-based climate solution.
In Canada, soil organic carbon stocks have been increasing, however, regional trends differ substantially (Figure 1). In the Prairies, the largest agricultural region in Canada, soil carbon has been increasing for decades. This has been due to three main practices: reduction in summer fallow management, widespread adoption of no till practices and increased conversion to perennialized systems. However, in Central and Atlantic Canada, soil carbon has steadily declined. Practices like non-diverse annual cropping systems, heavy tillage and a lack of carbon inputs from cover crops or crop residue have caused massive degradation in these soils. Soil degradation in Central and Atlantic Canada could be slowed by switching to best management practices which also provide other benefits to the soil. Reducing soil disturbance caused by tillage can improve soil health, while perennializing the rotation (by adding cover crops) can reduce nutrient losses and improve soil structure (4). Other best management practices and regenerative agriculture practices provide a range of benefits to the soil ecosystem in addition to increasing the carbon storage rate of agricultural systems, so adoption is a win-win. See the table below for the carbon storage rate that can occur when using different practices (Table 1).
Table 1: A comparison of best management practices for carbon storage on managed soils.
|Practice||C Storage Rate
(Mg C ha-1 yr-1)
|Replacing annual with perennial species||0.6||Canada||5|
|Adopting no till||0.23||Saskatchewan||6|
|Removing summer fallow||0.23||Prairie region||5|
|Compost Application||0.9 – 1.3||Ontario||7|
|Grass on Golf Courses||0.9 – 3.6||United States||9, 10|
We looked at projections based on practice adoption to see how much carbon could be offset by 2030. If 50-75% of agricultural producers across Canada adopted some regenerative or best management practice, this would offset ~17% of Canada’s greenhouse gas reduction target for 2030 (219 Gigatons of CO2 eq) (2). This amount also offsets approximately half of annual agricultural greenhouse gas emissions, which is a huge step for the agricultural industry.
This internship also uncovered the potential for non-agricultural arable lands for carbon sequestration. Urban, suburban and rural areas containing residences, golf courses, parks and conservation areas all have potential for soil carbon sequestration. Practices that improve carbon input (leaving leaf litter or lawn cuttings) and reduce soil disturbance (using perennial grass mixtures or planting woody vegetation) can improve long-term carbon storage. These practices also provide soil ecosystem services and improve the health of urban ecosystems.
Look out for the report “Soil Carbon Sequestration in Canada’s Managed Soils” by Soil Conservation Council of Canada and Compost Canada that I worked on during my internship project.
- Riebeek, H. The Carbon Cycle. NASA Earth Observatory. (2011). Retrieved from: https://earthobservatory.nasa.gov/features/CarbonCycle
- Statistics Canada. Table 32-10-0407-01 Tenure of land owned, leased, rented, crop-shared, used through other arrangements or used by others
- Agriculture and Agri-Food Canada (AAFC). Environmental sustainability of Canadian agriculture: Agri-environmental indicator report series – Report #4. (2019).
- Paustian, K., Lehmann, J., Ogle, S. et al.Climate-smart soils. Nature 532, 49–57 (2016). https://doi.org/10.1038/nature17174
- VandenBygaart, A. J. et al. Soil organic carbon stocks on long-term agroecosystem experiments in Canada. Canadian Journal of Soil Science. 90, 543–550 (2010).
- McConkey, B. Haugen-Kozyra, K. & Staley, D. Prairie Soil Carbon Balance Project: Soil Organic Carbon Change on Direct-Seeded Farmland in Saskatchewan. Saskatchewan Soil Conservation Association. (2013). Retrieved from: https://www.ssca.ca/prairie-soil-carbon-balance-pscb
- Yang, X. et al. Organic carbon and nitrogen stocks in a clay loam soil 10 years after a single compost application. Canadian Journal of Soil Science. 94, 357–363 (2014).
- Poeplau, C. & Don, A. Carbon Sequestration in Agricultural Soils via Cultivation of Cover Crops – A Meta-Analysis. Agriculture, Ecosystems & Environment. 200, 33-41 (2015).
- Qian, Y. & Follett, R. F. Assessing Soil Carbon Sequestration in Turfgrass Systems Using Long‐Term Soil Testing Data. Agronomy Journal. 94, 930–935 (2002).
- Selhorst, A. L. & Lal, R. Carbon budgeting in golf course soils of Central Ohio. Urban Ecosystems. 14, 771–781 (2011).