Going from Good to Better in Reducing GHG Emissions
Organic Agriculture Centre of Canada
Organic farming systems generally produce lower greenhouse gas (GHG) emissions than conventional farms, mainly because they don’t use synthetic nitrogen fertilizer.
Yet organic farmers could do even better if they increased their production efficiency by using farm-level and sector-wide strategies.
The main objective of a recent research study is “to identify both the farm-and-system-level changes that bring about greater energy efficiency and reduced GHG emissions.”
The strategies are organized in an efficiency-substitution-redesign framework, which goes from the simple to the complex.
For example, manure is a significant source of the greenhouse gas methane (CH4). An efficiency stage strategy would involve minor changes to existing operations, such as reducing the surface area of a manure pile. A substitution strategy could be improving manure application techniques to minimize losses. In a redesign strategy, the length of time animals are outdoors would be extended and manure would be deposited primarily on the fields where needed.
Proper manure management can play an important role in methane reduction, says Rod MacRae, lead author of “,” published in the Journal of Sustainable Agriculture.
Other main agriculture GHG emission sources in Canada are: carbon dioxide (CO2), from the breakdown of carbon in soil, consumption of fossil fuels and use of synthetic fertilizers and pesticides; and nitrous oxide (N2O), mainly from the inefficient use of nitrogen (N) fertilizers, releasing nitrogen to the air and water.
“In general,” states the report, “farm-level strategies are of three kinds: improving energy efficiency, storing carbon and generating biomass offsets.”
Energy efficiency illustrates the strengths and weaknesses of organic farming.
For example, commodity-based studies consistently show lower energy consumption in organic production per unit of land. But when the comparison shifts to energy consumption per yield, organic is sometimes higher.
Potatoes and apples have shown higher energy use based on yield, likely because organic production has not been as highly developed as other sectors, such as field crops and dairying. Enhanced production strategies could result in higher yields and reduced energy use.
From a systems perspective, organic farming provides an opportunity to integrate the four pillars of a global warming strategy: GHG emissions reduction, carbon sequestration, biomass offsets and adaptation.
Relative to most types of conventional farming, benefits of organic farming include reduced soil erosion, more carbon storage, elimination of synthetic fertilizers and pesticides and reduction of nitrous oxide and methane emissions.Â
Most of the study focuses on mitigation, but there is a section that indicates organic farming systems also represent a form of adaptation.
Mitigation involves taking action to reduce GHG emissions, such as using less oil, gas or other fossil fuel energy. Adaptation involves strategies to tolerate the effects of climate change, such as building soil organic matter to permit better plant growth during droughts and floods.
“Given organic agriculture’s better performance related to protecting soil resources, and greater adaptability to less suitable moisture conditions, using organic production for cropland remediation . . . is a feasible sectoral development strategy,” states the report.
Based on total land use, organic production is more efficient because it doesn’t reduce the quality of the land base and requires lower levels of off-farm energy and nutrients. “Consequently, organic farming is better placed to adapt to the price shocks and potential shortages associated with synthetic nitrogen and phosphorus fertilizers.”
Organic alternatives include biological nitrogen, found in manure, legumes and green manures – crops grown for plowing back into the soil.
The study notes there is Canadian evidence that composted cattle manure, often used by organic farmers, has significantly lower methane emissions than stockpiled manure and liquid slurry. “Aeration in composting reduces methane production, which is much higher in stockpiled, and especially liquid, manure,” said MacRae.
The study states that Canada’s organic sector has slowly been improving its response to collective initiatives, creating the possibility of energy efficiency being addressed at a national scale.
The quantity and types of energy available in the future will likely determine which strategies are most appropriate. “The more constrained the world is to produce petroleum-based inputs, the more favorable biological processes, of the kind favored in organic systems, will look."
This is the first of a two-part series based on the study . See Part 2.
This article was written by Steve Harder on behalf of the OACC with funding provided by Canada’s Organic Science Cluster (a part of the Canadian Agri-Science Clusters Initiative of Agriculture and Agri-Food Canada's Growing Forward Policy Framework). The Organic Science Cluster is a collaborative effort led jointly by the OACC, the and industry partners. For more information: oacc@dal.ca or 902-893-7256.
Posted October 2010