Effluent systems are generally designed to have the storage ponds empty going into the winter.
Having the ponds empty increases effluent storage capacity as rainfall exceeds evaporation in this period and paddocks are generally too wet to apply effluent as it increases the risk of nutrient run-off and waterlogging.
By reducing second pond volume, farmers can maximise fill capacity, plus applying an autumn application of effluent will provide a free boost to winter pasture growth.
This is due to the large amount of nitrogen and potassium which is often held.
When applying effluent:
● Leave at least 150mm of effluent in the bottom of the ponds to prevent cracking and future leaking.
● If effluent is recycled for yard washing, then enough effluent must be left in the pond for this to continue.
● Rotate effluent application in paddocks and regularly soil test application areas.
● Avoid grazing paddocks until at least 21 days after effluent application.
● Graze prior to effluent application as it allows greater penetration of UV rays into the canopy to kill potential pathogens contained in the effluent.
● Transition cows should not be grazed on high potassium paddocks — including paddocks where effluent has been applied.
● Young stock should not have access to areas where effluent is stored or has been applied.
Ideally test the effluent prior to application to assess the nutrient concentrations, so appropriate application rates can be calculated.
If you don’t have a recent test you can assess an appropriate application rate by using Dairy Australia’s Effluent and Sludge Calculator: www.dairyingfortomorrow.com.au/tools-and-guidelines/nutrients-from-effluent-and-sludge-calculator
The first effluent pond should also be de-sludged every couple of years, depending on the size of the pond and herd size, to ensure sludge does not build up and find its way into the second pond.
First pond sludge is an extremely useful resource and acts as a slow release fertiliser, still providing additional growth 12 to 18 months after application.
Sludge application can be a good way to kick-start a rundown area of the farm and can be incorporated during a cropping phase.
All dairy farmers are required to keep dairy effluent on-farm and out of waterways.
By ensuring your ponds are empty before winter it will assist you to manage your effluent system over the wet months.
For more information, visit: agriculture.vic.gov.au/livestock-and-animals/dairy/managing-effluent
- Agriculture Victoria dairy extension officer Richard Smith
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