Reducing emissions in dairy farms

Agriculture accounts for approximately 16% of Australia's total greenhouse gas emissions, with direct on-farm emissions from dairy farms contributing about 19% of this – about 3% of total national emissions.

Each individual dairy farm will have a different emissions profile, depending upon their farm system. But a typical breakdown of emissions from a dairy farm is approximately:

• 60% to 70% from methane produced by the rumination of cows
• 10% from nitrous oxide that arises from dung and urine
• 10% from energy and indirect losses from wet soils
• 10% from the production of electricity used on-farm

Knowing how much each of the various sources of your on farm emissions contributes to the total farm emission is important to help determine where and how to invest your time and effort to reduce them. The Dairy Greenhouse Gas abatement strategies calculator can help to determine your farm's emissions. The Dairy team can assist in providing information on dairy farm emissions.

Reducing your emissions

An emission trading scheme or carbon pollution reduction scheme would affect dairy farms. But there are many opportunities for dairy farmers to reduce their total net emissions or emissions per unit of production now.

For example, you can reduce emissions either by:

• directly reducing the total tonnage of greenhouse gasses produced, or
• reducing the amount emitted per unit of production (the amount of greenhouse gases emitted per kilogram of milk solids produced)

You can achieve a net reduction of emissions by using feed additives and rumen modifiers. This reduces enteric methane or nitrogen inhibitors, which in turn reduces nitrous oxide losses from dung, urine and soil.

Some of the strategies to reduce emissions from the major sources of on-farm greenhouse gases are also in line with best management practices and can also provide a positive productivity benefit, such as:

• better targeted and timing of fertiliser applications to reduce nitrogen losses
• balancing the feed rations for cows to ensure correct energy, protein and fibre ratios to maintain a well functioning rumen
• ensuring stock are adequately fed to achieve genetic merit and optimum milk production levels

These improvements in farm management can also lead to improved productivity and profitability, though they may result in increased carrying capacity or milk production. This could potentially lead to a net increase of greenhouse gases produced in total, even if there's a reduction in the greenhouse gases per unit of production (per litre of milk or kilogram of milk solids produced).

Emissions can also be offset by 'locking' carbon up in various forms such as tree plantings, which can also provide additional benefits like shade and shelter.

Research into soil carbon to offset emissions

Soils contain carbon in the form of decaying organisms or plant matter, humus, or as charcoal resulting from burning. Each of these forms of carbon build up and decline at different rates, depending on the:

• type of production system
• management practices
• rainfall
• soil type

Research is currently underway to investigate how soil carbon might contribute to a carbon offset market. Raising the carbon levels in soil can potentially store (or sequester) carbon and have positive soil health benefits. However, soil carbon can be difficult and costly to increase, particularly if already starting with high levels.

Increasing the net soil carbon can be difficult to achieve on dairy farms as many already have high levels, and the potential to increase these over current levels may be limited. Also, soil carbon can be easily lost through management practices such as cultivation or because of drought.

More information

Further useful information on emissions, carbon, agriculture and farming