Perennial grasses mitigate climate change
What do you need to know?
Climate change is one of the greatest threats to our environment. To help mitigate the negative effects of climate change by 2100, fossil fuels need to be replaced by renewable energy sources. A promising renewable energy source is plant material (biomass) that can be turned into biofuel. Biofuel can be used, for example, for heating and generating electricity. However, not all plant species produce equally high biomass, therefore, it is important to research different plant species to find the best possible candidates.
Some plant species not only produce a lot of biomass, but they also increase the amount of carbon that can be stored in the soil. Soil carbon storage is another way to mitigate climate change. Warm season perennial grasses (WSGs) are the recommended species to grow for biomass in Southern Ontario because of their high yields, low maintenance, and tolerance to many environments. This study confirmed that biomass crops store more carbon than agricultural crops, thus suggesting some changes to land use patterns to help mitigate climate change.
Why is this research important?
In the early 1900s, deforestation efforts to make room for more agricultural land, severely depleted the amount of carbon in the soil. Since then, soil carbon stocks have continued to decrease while atmospheric carbon concentration soars. The United Nations and scientists worldwide agree that we must collectively reduce our greenhouse gas emissions to slow climate change. Plants help with this in two ways: by keeping carbon into the soil and serving as a net emission-free energy source. This is well known, however the efficacy of warm season perennial grasses to absorb carbon over long periods of time is not well understood.
Warm season perennial grasses (WSGs) are easy to produce as growers have the infrastructure needed to scale-up cultivation and have many benefits, including erosion-prevention. In Southern Ontario, they are grown on less productive or marginal lands. Before land is converted to growing WSGs, it must be verified that WSGs can store significant amounts of carbon to validate the change in land use. The uncertainty of the future environmental growing conditions challenges our predictions, so biogeochemical modeling is used to analyse growth in several different warming scenarios over the next century.
What did the researchers do?
A biogeochemical simulation, DayCent, was used to model the effects of environmental conditions on soil carbon content and greenhouse gas (GHG) emissions. Input data was used from the Intergovernmental Panel on Climate Change, Environment Canada and field data to simulate two climate warming scenarios over the next 100 years: moderate warming and high warming. Previous environmental data of agricultural crops at the same research site from 1981-2015 was used as a control. This observed data was compared to DayCent modeled data to prove the accuracy of the simulation.
To evaluate the changes in carbon storage over the 21st century in moderate and high climate change warming scenarios, the following measurements were taken:
- The amount of carbon in the soil of agricultural crops and biomass crops from 1913-2100
- Above-ground and below-ground biomass of two biomass crops, per decade from 2011-2100
- The rate of carbon absorption of biomass crops over the 21st century
The main crops grown in this experiment were:
- Biomass crops: Warm season perennial C4 grasses (WSGs) (Switchgrass and Miscanthus)
- Agricultural food crops: Corn-corn-soybean-winter wheat (CCSW)
What did the researchers find?
- Moderate warming will result in an increase of 10.1◦C, and high warming an increase of 13.1◦C, by 2100
- Corn-corn-soybean-winter wheat crop rotation slowed soil carbon depletion steadily over the century
- WSGs can sequester soil organic carbon
- Of the two WSGs, Miscanthus has a higher biomass than Switchgrass and thus higher rates of carbon sequestration
- Carbon sequestration is maximized within 20-30 years of planting, then stabilizes by 50-60 years
- The soil carbon stock will quickly deplete if WSG crops are converted back to food crops
- Miscanthus and Switchgrass are both suitable energy crops, since they exceed the required carbon sequestration threshold (CCSW)
About the researchers
Dr. Naresh Thevathasan is an Associate Professor at the University of Guelph’s School of Environmental Science (SES) studying the field of Plant and Tree influence on Environmental Health, with a focus in biomass crops and carbon sequestration. Dr. Mahendra Thimmanagari is a bioproducts specialist for the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), and special graduate faculty at the University of Guelph’s Bio-Renewable Innovation Lab. Dr. Andrew Gordon is a University Professor Emeritus at the SES, who studies forest ecology and carbon dynamics. Dr. Paul Voroney is a Professor for the SES who studies soil biology and biochemistry. Dr. Marek Jarecki and Dr. Amir Bazrgar are Research Associates with the University of Guelph’s School of Environmental Science. Dr. Kumudinie Kariyapperuma was a Research Associate with The University of Guelph from 2011-2019 and is now the Research Facilitator of Natural Sciences at Wilfred Laurier University. Sowthini Vijayakumar is a PhD Candidate at the School of Environmental Sciences. Dr. Bill Deen was an Associate Professor in the Department of Plant Agriculture and is now retired. All authors are working at the University of Guelph, Guelph Campus, Guelph, Ontario, Canada.
This study was conducted at the University of Guelph’s Elora Research Station in Ariss, Ontario. Elora Research Farms is one of 10 research sites operated under the Department of Plant Agriculture. Most of the station is used to produce feed and dispose of manure for the University’s cattle herds. Other uses include field crops research such as cereals, oilseeds, edible beans and forages. Research facilities are comprised of four buildings for on-site sample storage and machinery.
Warm season C4 grasses, Corn-corn-soybean-winter wheat (CCSW), herbaceous biomass crops, climate change mitigation, agriculture, soil carbon sequestration, climate scenarios, DayCent simulation
Jarecki, M., Kariyapperuma, K., Deen, B., Graham, J., Bazrgar, A. B., Vijayakumar, S., Thimmanagari, M., Gordon, A., Voroney, P. & Thevathasan, N. (2020). The Potential of Switchgrass and Miscanthus to Enhance Soil Organic Carbon Sequestration—Predicted by DayCent Model. Land, 9(12), 509. https://doi.org/10.3390/land9120509