Emergency disposal of milk
Emergency disposal of milk may be necessary in certain situations such as:
- refrigeration failure due to power failure or breakdown in cooling system leading to milk spoilage
- when tankers are unable to access property due to emergency events, fire, flood, or transport issues
- when the milk is contaminated on the farm, therefore making it unsuitable for processing
- if the farm is placed under quarantine with restrictions to access. This could occur in the event of an animal disease outbreak such as the presence of an animal disease.
Milk is considered a pollutant and must not be discharged into waterways. All methods for disposal of milk to land also need to ensure that the milk remains on the property. When milk is released into a stream or lake, it provides a food source for bacteria, which use oxygen in the water to live and grow. Bacteria growth following a significant spill of milk will cause stress, or death for fish and other aquatic life living in the waterway.
An emergency response plan that considers how milk will be disposed on farm should be prepared for each property to ensure that the milk remains on farm.
Milk disposal methods
Tractor mounted sprayers, effluent tankers and dairy effluent irrigation systems can be used to spray milk directly onto pasture. Milk should be diluted to a ratio of 1-part milk to 10 parts water and applied to freshly grazed pasture so that there is sufficient time between grazing’s for the milk to be taken up by the soil. If sufficient water is not available, then the milk should be sprayed onto the pasture followed by whatever fresh water is available or alternatively shed washings, to rinse milk residue off the leaves.
If milk is applied during winter apply milk to dry paddocks away from waterways. Sprinklers should be kept well clear of waterways and should be moved after each irrigation.
Feeding to livestock
Milk can be fed to livestock and is nutritionally high in energy, protein, and fat. Feeding milk to livestock can only be considered if the milk is fit for purpose and does not contain antibiotics. It also needs to be contained, fed, and stored so it remains on-farm and doesn’t spoil. If in doubt consult a veterinarian prior to commencing feeding.
Milk can be spread over a piece of non-productive land that is positioned well away from waterways and houses. This option has the potential to damage pasture and create odour. To minimise this impact, each application should be carried out on a different site, followed by flushing with water to wash the milk off the leaves and to help it integrate into the soil. Try to apply the milk to as much land area that is practically possible. Ideally the sacrifice area will be an area intended for cultivation in the future.
Discharging into effluent ponds
Alternative options for disposing of milk should be considered before directing milk into effluent ponds. If possible, by-pass ponds and pump the milk straight to pasture via a sump if possible. Effluent ponds that accept milk will produce odour, and the milk will reduce the ability of the pond to treat effluent. This is because milk has a high biological oxygen demand and organic loading. Ponds that have had large amounts of milk added will take many months to recover and severe odour problems may occur for many months to follow.
If alternative milk disposal options are not feasible, then a maximum of 2 days of milk can be added to a well-functioning, adequately sized pond within a fortnight (State of NSW 2008). If ponds are used to recycle water for yard cleaning disposing of milk to the effluent system should be avoided.
The addition of waste milk to effluent ponds has shown to increase methane production by the ponds which generates odour. Mixing effluent and milk in confined spaces or buildings or any enclosed effluent storage facilities is not recommended as it can produce a build-up of gases (Dairy NZ 2021).
- Dairy NZ, 2021, Milk Disposal, accessed 28th May 2021
- Government of Western Australia 2018, Disposing of Milk, accessed 31st May 2021
- Landcare Research New Zealand 2012, Revised methane emission factors and parameters for dairy effluent ponds, accessed 31st May
- State of NSW, 2008, Environmental management guidelines for the dairy industry, viewed 11th June 2021.