Trevor Thomas – Measuring Greenhouse Emissions on a Dairy Farm
Farmers Taking Action on Climate Change CASE STUDY 2.3
LONGWARRY
Trevor Thomas is a dairy farmer from Longwarry, Victoria, who has ran his family’s farm since 1992. A third generation dairy farmer, Trevor accepts that climate change is a reality, and sees both adapting to a drier and warmer climate and understanding the sources of greenhouse gas emissions on his farm as critical to managing his business risk. KEY POINTS
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Trevor has been adapting his practices to help manage the changing conditions. “The bottom line is if you don’t get the rain, you don’t get the grass”. As a result Trevor has developed a range of strategies in pasture and crop management to help manage climate variability.
Trevor has also undertaken a greenhouse emissions calculation, in order to understand the greenhouse gas emissions profile of his farm. Greenhouse gas emissions are essentially a loss of energy from the farming system, and if conserved can increase production efficiency on farm. Trevor said that it is “unlikely that I am carbon neutral” and wanted to test this assumption.
The emissions profile on Trevor’s farm was calculated using the Dairy Greenhouse Abatement Strategies (DGAS) calculator, a tool made available through the Dairying for Tomorrow website. DGAS allows dairy farmers to find the sources of greenhouse gases for individual farms and to see the direct impact of farm activity on the level of emissions.
Dairy farm emissions can be calculated in two ways - Tonnes of carbon dioxide equivalent (CO2e) per tonne of milk solids (MS) (where MS refers to milk fat and milk protein) of tonnes of CO2e per hectare. We use the term CO2e as a standardised way to describe all greenhouse gases. In the DGAS calculator methane is assumed to have a greenhouse warming potential 23 times that of carbon dioxide (CO2) while nitrous oxide has a greenhouse warming potential of 310. The total greenhouse gas emissions for Trevor’s farm are found in Table 1.
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Farm details
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Table 1: Total greenhouse gas emissions of Trevor Thomas’ farm compared to Gippsland dairy farm ranges
| Emissions | Tonnes of CO2e per tonne of Milk Solids (MS) | Tonnes of CO2e per hectare |
|---|---|---|
| Trevor Thomas’ farm |
17.5 |
9 |
| Gippsland average # | 13.6 | 10.1 |
| Gippsland Range # | 10.4 – 16.1 | 4.9 – 17.7 |
| Victorian average # | 13.5 | 9.2 |
| # Figures calculated by University of Tasmania project Accounting 4 Nutrients (Pers comms. K.Christie, 2010) | ||
Baseline contributors to total emissionsKey sources of emissions on Trevor’s farm were methane (54%), from rumen fermentation, and nitrous oxide (N2O) (22%) derived from fertiliser, dung, urine and indirect sources from leaching and ammonia. Embedded emissions (or emissions from pre-farm processes) from bought in feed, such as hay and silage, accounted for 16% of the total, whereas energy from fuel and electricity contributed only 8% of total emissions on farm. (This information is shown in the pie chart below.) |
An emissions calculator, such as DGAS, allows farmers like Trevor to assess farm changes and the impact on greenhouse gas emissions sources. Such calculators are flexible and allow calculations based on your situation.
Besides continuing to improve average cow productivity (i.e. through improved pasture management), actions which can help Trevor reduce his farm’s methane and nitrous oxide emissions include:
- Extended lactation: can reduce the energy demand of cows and methane by approximately 10%. Extended lactation has other benefits, such as reducing peak workload, cow health problems (due to less calvings) and less heifer replacements are required. Milk in the extended lactation phase is higher in milk solids, making the milk more valuable per litre and there may be price incentives for milk produced outside peak supply months. Trevor has always considered extended lactation as an option for his herd, and has selected breeds suited for extended lactation.
- Dietary oils: The use of oils or tannins in feed is an active area of research and has shown that such supplements in a cow’s diet can reduce methane emissions. For every 1% of oil introduced in the diet (maximum 6%) there will be a 3.6% reduction in methane emissions. Introducing oils in autumn and summer, when pasture fat content is lower, is a way to reduce methane at no cost to production. “Dietary oils should be easy for feed companies to add into the diets” said Trevor.
- Nitrification inhibitors: coated fertilisers can reduce nitrous oxide losses by up to 40%. Reviewing the rate, timing and source of fertilisers on farm can also reduce nitrous oxide emissions.
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On farm energy use (carbon dioxide from fuels and electricity) Trevor is involved with a project run by the Bass Coast and Western Port Catchment Landcare Network that aims to understand more about greenhouse gases, reduce on farm waste, improve water efficiency and increase energy use efficiency. Project Officer Peter Ronalds attributes the success of the project to an increased awareness of how resources are used on-farm. He says “knowing what resources you are using allows strong business cases to be built around management decisions.” Whilst emissions from energy use are often lower than from animals, taking action in this area could be a cost effective place to start. Audits of dairy sheds have revealed many opportunities for farmers to reduce their carbon dioxide emissions and save money on their power bills. These ranged from simply servicing all equipment to ensure that it is running efficiently, to innovations such as refrigeration heat exchange units and solar photovoltaic systems. Trevor has considered using solar power, as well as utilisation of waste heat from refrigeration units. “I am keen to do something about it now because electricity is only going to get more expensive and the savings can be instantaneous” said Trevor. |
“By looking at these strategies I hope to contribute to a reduction in greenhouse gases, which will hopefully be a win for the environment and a win for me in terms of cost and production at the same time”.
Acknowledging that the climate is changing and that managing emissions is a challenge for dairy farmers Trevor pointed out that, “we definitely have to change – emissions reduction and production improvement options on farm are all linked together”.
For more information call DPI on 136 186
Dairying for Tomorrow (DGAS Calculator)
www.dairyingfortomorrow.com.au
DPI is seeking positive and practical stories about climate change action. Contact us on 136 186 if you have a story to share.
View all the Farmers Taking Action case studies online at www.dpi.vic.gov.au/climaterisk
Through the Future Farming Strategy, the Victorian Government is providing information to enable farm businesses to plan for climate change.
