In preparation for wet periods it is time to start making sure that you have maximum storage in your effluent ponds.
Empty ponds before late autumn, to allow for winter and spring storage. In regions with winter dominant rainfall, it is usually too wet to apply effluent to land over the winter months, so an effluent pond is used to provide storage until warmer, drier weather returns. The pond can only provide storage if it is emptied before the start of the wet period.
Managing Storage Levels
Key messages:
• Plenty of storage means more management flexibility and better pasture responses
• Minimise effluent volumes
• Keep the pond low
• Never allow effluent to enter a waterway, and
• Increase storage to avoid winter and spring irrigation
Effluent storage ponds offer flexibility, allowing farmers to store effluent when paddocks don’t need any more water and plants can’t use the nutrients that would be applied. However, a full pond has no storage capacity and can become a liability if there is wet weather on the way.
Ideally, there should be enough effluent storage to cope with all the effluent generated during the months when rainfall is greater than evapotranspiration. Aim to have the pond empty by the middle or end of autumn depending on your annual rainfall distribution and expect that it will be getting near full towards the middle of spring during a wet year. Some farmers like to build larger storage ponds to get them through the entire non-irrigation period, and other very busy times of the year. The smaller the pond’s storage capacity, the more frequently it must be managed.
Keep the pond low, by reducing any unnecessary water entering the pond from leaks and water wastage. Do a water audit to identify any potential water savings. Recycling effluent water for flood washing feedpads and using rubber scrapers are ways of reducing the amount of effluent entering the pond.
Irrigate from the pond any day when soil conditions are suitable, especially if you are still in the storage period and the pond is getting full. Spreading ‘small amounts and often’ will also help to ‘keep the pond low’.
If irrigating small amounts often is not looking like it will prevent the pond from overflowing, it is still better to spread it in the paddock as lightly as possible, than let the pond overflow. Choose the most freely draining paddocks available or those furthest from waterways. It is illegal to allow effluent to enter a waterway.
Managing pond levels through winter and spring is hard work as it’s muddy and cold and won’t provide the best agronomic return from the nutrients in the effluent. As soon as conditions allow, consider ways of increasing your storage capacity to avoid this situation.
The best approach is to keep the pond level low and get ready to go when conditions are right to apply effluent.
For further info, farmers can utilise ‘Effluent Management’ resources on the Dairy Australia website.
Information credit to DairyTas.
