Exploring Dairy's Greenhouse Gas Footprint
Every action taken at the farm to reduce greenhouse gas emissions helps improve the industry's public image
Dairy farms, along with beef farms, have been targeted for their contributions to the global carbon footprint, particularly through the sustainability analysis used by grocery retailers and independent environmental groups. Although Canada's dairy farm contributions are comparatively lower than other countries' greenhouse gas emissions (GHGs), every action taken at the farm to reduce these emissions helps improve the industry's public image. Research initiatives that help the sector reduce its carbon footprint are an important part of that work. This helps show the Canadian dairy industry is proactively working to minimize any negative environmental impacts and increase the sector's sustainability at every opportunity.
In April 2015, scientists from across the country met in Ottawa to discuss dairy farm GHGs. Canada's dairy sector is a long-time supporter of research in this area, and is one of its strengths. While it could be easy to disregard the importance of greenhouse gas research, or discredit the topic as something just for environmentalists, efficient dairy production and reducing GHGs go hand in hand. GHGs are nutrients or lost energy in another form. Minimizing their loss can help a farm's bottom line.
The scientists wanted to identify tangible practices that would fit within the measures Canadian dairy farmers have adopted as they manage their farms with a vision for long-term viability. Their discussions focused on three areas of a dairy farm and how they interact together -the cow and emissions from the barn, manure management, and manure application to fields.
GHGs from farms include methane, nitrous oxide and carbon dioxide. Methane comes primarily from cows and manure management. Nitrous oxide can arise from manure management, but its main source is fields. Carbon dioxide from animals is not counted in GHG calculations, but there is potential for soils to soak up carbon dioxide, known as carbon sequestration.
Emissions from cows
Methane emissions from cows are called enteric emissions. These can be very significant. According to Canada's 2015 National Inventory Report, 27 per cent of the country's methane emissions come from agriculture, and the largest contributor of these are enteric livestock emissions. Researchers have been working for years at finding ways to reduce these losses. A few promising areas include:
- Diet optimization. Improved health and nutrition for dairy animals increases their milk production. Increases in production efficiency have been shown to reduce GHGs by limiting the amount of inputs required for a given output of milk.
- Use of lipids. Adding lipids to cattle diets has been shown to decrease the amounts of enteric emissions without increasing fats to the point of negatively affecting digestion.
- Forage management. Methane emissions can be reduced by harvesting forages at optimum maturity to maximize the digestible energy of forages fed to cows. Ensuring forages are well preserved is another beneficial strategy.
Researchers agree certain factors will determine which GHG management techniques will work best on a farm. For example, while anaerobic digestion has the potential to significantly decrease GHG emissions from manure, it isn't feasible to install a digester on every dairy farm. Other barriers to using this technology include installation costs, the availability of manure and additional organic feedstocks, electricity or natural gas prices, the ability to connect to grids, and many other issues that prevent the widespread use of digesters. However, the majority of farmers who have installed an anaerobic digester have had great success.
Many farmers may find value in solid-liquid manure separation. This reduces methane production from manure storage. Separation is significantly cheaper than anaerobic digestion. It reduces the need for manure storage capacity and provides a potential bedding source.
Other management practices that could reduce methane production from manure storage include completely emptying the storage unit or applying a straw cover to the storage tank. While there are management considerations for both of these practices, such as whether it is feasible to empty the storage or maintain a dry straw cover on the storage tank, they both could potentially reduce GHG losses.
In the fields
Researchers have examined several practices to reduce nitrogen losses from fields once manure and other nutrient sources have been applied. Nitrogen loss in the form of nitrous oxide, a GHG, or ammonia or nitrate leaching, can be significant. Minimizing these losses and increasing crop uptake can reduce costs.
Regardless of the farm's size or style, applied nitrogen losses can be reduced by optimizing nitrogen applications using soil and manure tests. Researchers have also found applying nutrients in the spring can potentially increase plant uptake and reduce the amount of nitrogen lost through leaching, runoff or gas.
Another promising area for reducing GHGs from fields is the increasing use of perennials in cropping. Researchers have found perennial forage crops store carbon at a higher rate than do annual crops. This helps increase soil organic matter and sequester carbon.
Many of the practices undertaken on a dairy farm to improve feed or nutrient efficiency may lead to financial savings, as well as GHG reductions. Dairy farmers can implement several practices to reduce their farm's environmental footprint, such as diet optimization, improved forage management for higher digestibility, and optimizing nutrient applications at the field level, particularly of nitrogen sources.
Producers are encouraged to speak with their nutritionist or agronomist to develop a plan of action. Farms with liquid manure systems may be able to reduce GHGs by completely emptying their manure storage, particularly if this is possible in spring.
Dairy producers are already doing a lot to reduce greenhouse gas emissions through the use of efficient production methods. They also continue to increase production capacity so they are able to produce the same quantity or even more milk with fewer cows. Ultimately, these strategies will make dairy farming more efficient, and improve the farm's sustainability and viability.
Karen Clark is assistant director, policy and sustainable development for Dairy Farmers of Canada, Tom Wright is a dairy cattle nutritionist for the Ontario Ministry of Agriculture, Food and Rural Affairs, and Mike Slomp is the industry and member services manager for Alberta Milk. The research comes from the dairy AGGP project (Agricultural GHG Program), with funding from Agriculture and Agri-Food Canada (AAFC) and Dairy Farmers of Canada, as well as the Dairy Research Cluster, which includes funding from AAFC, DFC, the Canadian Dairy Network and Canadian Dairy Commission.
This article originally appeared in the June issue of the Milk Producer magazine.
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