Effluent Management
Dairy Effluent
A 100 cow herd each year produces effluent equivalent to that of a township of 1 000 people. The Biological Oxygen Demand (BOD) is 10 times greater and can do extreme damage to local waterways. By law, ensure that all dairy effluent remains on the farm and does not leave the farm boundary.
- Dairy shed effluent can be a valuable fertiliser and soil conditioner. It is estimated that during one lactation a 100 cow herd deposits 80 kg Phosphorus (910 kg single super), 250 kg Nitrogen (540 kg Urea) and 270 kg Potassium (540 kg Potash) in the yards.
- Approx 8-10% of the daily effluent is deposited in the yard. A general rule of thumb to minimise nutrient overload, and soil structure and pasture damage, is to apply effluent to 4 ha for every 100 cows milked. If possible, rotate your effluent around different areas of the farm each year and spread over as large an area as possible/accessible.
- Applying dairy effluent on pastures and crops can boost pasture growth by utilising the nutrients, organic matter and water in the effluent. However, the levels of nutrient in a storage pond are less than fresh dung and urine. Have your ponds tested to work out the levels and rates of application.
- Do not graze areas where effluent has been applied for at least 2 weeks in the summer and at least 3 weeks in winter if daily application must occur.
- Apply effluent just after grazing when the pastures are low and weather is hot/dry. This ensures sunlight (UV radiation) and wind can penetrate to the soil surface to kill microbes.
- Applying effluent just after grazing also means pastures will not need to be grazed until the next rotation (several weeks) - ensuring animal health considerations are addressed.
- Do not allow young stock (under 12 months) to graze or have access to treated areas. Do not allow drains from treated areas to flow into areas with young stock. This is to help reduce the risk of infections especially from Johnes, as young stock have not yet built up immunity to cope with such diseases.
- Consider applying effluent to the lower fertility paddocks, in order to boost organic matter and nutrients.
- Consider recycling your effluent for yard wash-down to minimise the amount of freshwater entering the system.
- Crusting of effluent ponds is generally an indication that the pond is overloaded and too small for your system. The bacteria can not keep up with the effluent coming in and can not breakdown the sludge. Your local effluent officer can work out the size of the system you require.
© The State of Victoria, 1996 - 2009.
This document was last reviewed on 27/10/2008