Reducing greenhouse gas emissions from agricultural lands
Cattle and forage on the landscape provide many economic and ecological benefits to society and the environment:
Canadian beef is a safe, secure and healthy food source; cattle and forage producers are an integral part of the rural
fabric and rural economy; perennial forage and grasslands help regulate
water flow, provide habitat for wildlife and store carbon. In Manitoba alone,
grasslands make up over 2.4 million hectares of the total farmland, storing
an estimated $9.4 million worth of carbon on an annual basis. How this land
is managed is an imporant consideration in the quest to better understand
and reduce agriculture’s contribution to greenhouse gas emissions.
Plants and soil are stores of organic carbon. Plants remove or sequester
carbon dioxide from the atmosphere to add to this reserve of carbon in the
soil. Soil carbon can in turn be released back to the atmosphere, depending
on a number of factors that influence whether farmland is a net source or
sink of carbon. To shed further light on the impact of land management
decisions on carbon storage, two graduate students, Trevor Fraser and Amanda Taylor, worked with soil scientist Brian
Amiro to study carbon dynamics in various cropping systems.
Trevor measured changes in carbon balance when perennial grassland is converted into annual cropping. He found that
there is a net loss of carbon with this conversion. “Our study showed that perennial grassland converted to annual
cropping loses more carbon than perennial grasses can sequester in a season. This loss continues beyond the year of
conversion. We measured carbon exchange in the second growing season after conversion and found carbon is still
being lost,” Fraser stated.
Figure 1. Cumulative Net Ecosystem Productivity (prior to
harvest removals) in the 2010 growing season (Taylor).
Amanda’s research looked at long-term carbon cycling, comparing carbon
exchange over three different cropping systems during the growing
season. Carbon exchange between the land and atmosphere potentially
dominates the greenhouse gas balance. While Taylor found some
variability in the net carbon exchange in the perennial system due to
weather differences, the annual cropping systems resulted in a net loss of
carbon to the atmosphere. “It is likely that soils with high carbon content
have the greatest potential to lose carbon when they are switched over
from perennial to annual cropping systems,” observed Taylor.
A better understanding of greenhouse gas transfer in agricultural systems is needed to identify Beneficial Management
Practices (BMPs) on a whole-system basis, including both crops and livestock. Into the second year of a four-year, $4.3
million project, a team of ten scientists and 13 collaborating organizations led out of the University of Manitoba is
providing new science-based knowledge of net greenhouse gas emissions related to cow-calf production systems in
western Canada. Complementing the field-based greenhouse gas research, current cattle-based research includes
evaluating dietary strategies for reducing methane emissions and understanding the potential for nitrous oxide
emissions from manure and bedding packs. Continuing her research as a Ph.D. student with Brian Amiro, Amanda
Taylor’s research now focuses on quantifying the impact of cattle grazing on greenhouse gas emissions. This new
information will be combined with previous knowledge to provide whole-system modeling assessments and to identify
cost-effective BMPs that will assist agricultural producers in making sound land-use decisions.
Agriculture and Agri-Food Canada’s Agricultural Greenhouse Gas Program (AGGP) provided $3 million towards this initiative.
Contact Brian Amiro ([email protected]) to learn more of this and other AGGP research. Both Amanda and Trevor
successfully defended their Masters’ theses on this research and have submitted manuscripts for publication. Congratulations!
Repurposing processed dairy manure as bedding is gaining ground in Manitoba. A recent
visit to Rosser Holsteins hosted by Henry Holtmann sparked interest among the researchers
present. Of particular interest was how manure nutrient and potential pathogen dynamics
were impacted by the recently implemented bedding recovery technology. Existing dairy
farmer-researcher collaborations include the recently completed survey of Manitoba dairy
farms led by Kees Plaizier and the involvement of Nazim Cicek’s team in establishing an
anaerobic digestion system on the Sweetridge dairy farm.
Program update: Beneficial management practices for greenhouse gas (GHG) mitigation from agroecosystems
Research projects under this program span GHG flux measurements in annual and perennial rotations, influence of
synthetic and organic nitrogen fertilizer management on GHG emissions, nitrous oxide and methane emissions in cattle
overwintering systems, dietary influences on methane emissions from cattle, whole farm flux measurements,
refinement of modeling of GHG emissions from beef production systems, using fecal microbial communities for
mitigating enteric methane emissions, and economic modeling.
Information transfer efforts include the development of greenhouse gas learning materials for
grade school children as well as a dedicated GHG web resource. The National Centre for Livestock
and the Environment is the site for the Canadian Society of Soil Science Greenhouse Gas Field
Workshop July 22.
Agriculture and Agri-Food Canada’s Agricultural Greenhouse Gas Program provided $3 million to
support this $4.3 million initiative involving ten scientists and 13 collaborating organizations.
Summary of publications on GHG at the Trace Gas Manitoba long-term field research site:
A.J. Glenn, M. Tenuta, B.D. Amiro, S.E. Maas and C. Wagner-Riddle. 2012. Nitrous oxide emissions
Mario Tenuta will host the
from an annual crop rotation on poorly drained soil on the Canadian Prairies. Agric. Forest
CSSS TGAS MAN GHG tour.
Meteorol. 166: 41-49
A.J. Glenn, B.D. Amiro, M. Tenuta, C. Wagner-Riddle, G. Drewitt, J. Warland. 2011. Contribution of crop residue carbon
to total soil respiration at a northern Prairie site using stable isotope flux measurements. Agric. Forest Meteorol. 151:
1045–1054
A.J. Glenn, B.D. Amiro, M. Tenuta, S.E. Stewart and C. Wagner-Riddle. 2010. Carbon dioxide exchange in a northern
prairie cropping system over three years. Agric. Forest Meteorol. 150: 908-918
Laurie Connor co-authors sow group housing factsheet featured on US National Pork Board website
There is no one-size-fits-all group housing system for sows. Donald G. Levis, Levis Worldwide Swine Consultancy and
Laurie Connor, University of Manitoba, outline key housing design considerations and present the pros and cons of the
five most common group housing systems in the factsheet Group Housing Systems: Choices and Designs, part of a series
of factsheets and webinars pertaining to sow housing options. Access the full series of factsheets and webinars at
http://umanitoba.ca/faculties/afs/ncle/publications/info_sheets.html.
Movement away from individual stalls is emphasized in the draft Code of Practice for the Care and Handling of Pigs, now
available for public comment. See the NFACC release at http://www.nfacc.ca/news?articleid=198 for more information.
Presentation slides of NCLE seminar on anaerobic digestion in Wisconsin and Manitoba now available online
If you missed the April seminar or would like to revisit this detailed review, the presentation is available on our website.
Seminar presenter Elsie Jordaan, Ph. D. candidate, was also featured in a subsequent article in the Western Producer.