Cost effective, council compliant effluent management can be simple and easy. For a start, there's really only two components of an effluent management system:
- Storage - also referred to as 'deferred irrigation', to meet council compliance regulations you need to have somewhere to store effluent for when conditions are not suitable for irrigation.
- Spreading - effluent is an excellent source of nutrients to promote pasture growth, but to keep the grass green, waterways blue, and the city folk smiling it has to be done the right way at the right time.
So here's the best practice guidelines for having an effluent management system that's cost effective, council compliant, and best of all...easy to manage!
Effluent Storage
Best practice? If you can, keep it simple and set yourself up with the following:
1. HPDE lined effluent pond
Where possible, this is by far the best type of effluent storage:
- Position the pond to allow gravity to move the effluent from the milking shed into storage. This minimises processing, eliminating the need for double pumping or solids separation, and saving on time, labour and energy costs.
- HDPE liners are the most cost effective pond lining option, are compliant with environmental and regional regulations, and are designed to last for over 100 years - so installing one of these should last a few generations! We recommend them because they provide the best in high tensile strength, tear resistance, and are welded together - no need for adhesives.
- Effluent ponds are the most cost effective storage option for installation, maintenance, and use with other effluent management equipment.
- Make sure you get the right size storage for your needs. Getting it right the first time will save a lot of headaches in the future. If you're unsure which size you need, contact an accredited dairy effluent system designer.
2. Storm water diverter
Install one of these to prevent too much water filling up the effluent pond during wet seasons. Excessive water will reduce the nutrient value while increasing the amount of effluent you have to store and spread.
3. Large, drive-in stone trap
A stone trap is recommended as best practice to remove stone, gravel and any other solids that have no nutrient benefits. This will give your pump and stirrer a longer life, and ensure the effluent pond capacity is effectively used. Stone traps that allow the tractor to drive in for cleaning out with a front end loader are less labour intensive, and therefore tend to be cleaned out more often.
Mix, don't separate
The heart of any good effluent management system is a good slurry stirrer. In most circumstances, mixing is recommended over separating simply because it is far more cost and time effective to deal with one product.
Why not just pump it?
If you don't stir, you decant off the green water, and solids continue to accumulate at the bottom of the pond reducing storage capacity. This also means a lot of the nutrients are being left at the bottom of the pond, so you're not getting as much value from your spreading. What's more...these nutrients deteriorate when left in the pond.
Further to this, if the solids continue to accumulate in the pond, eventually a contractor will need to be called in to clean out the pond, which is not only an added cost, but also time where the pond is unable to be used.
Thoroughly mixing the pond before pumping will also prolong the life of your pump as there will be less blockages from a more homogenous mixture.
What kind of stirrer is best?
A stirrer is one of the most important components of your effluent system, because the whole system relies on it's effectiveness.
For best results, an electric stirrer is recommended. Here's why:
- Power efficiency - an electric stirrer will get the job done faster for the same power requirements.
- Less labour intensive - electric stirrers can be set to work without needing someone there to monitor it.
- Easily adjustable - so the whole pond can be mixed evenly.
- Safer with less operator error.
To achieve a homogenous slurry mix it is critical the stirrer creates a strong horizontal thrust - no splashing about. This is where it is important to have a strong propellor designed for purpose, such as a Typhoon™.
Spreading/Irrigation
When selecting your pumping and irrigation equipment it's important the pump and irrigator will be able to handle the slurry solids. Some pumps can handle slurrys better than others, so if you're unsure, talk to an acccredited dairy effluent system designer who will be able to advise on your situation.
In terms of irrigator, best practice is to use a low pressure spreading system. Low pressure effluent spreading systems such as a Nevada RainWave™ slurry tanker, RainWave™ drag hose system, or traditional travelling irrigator cause less volitisation than high pressure systems, meaning more nutrients make it to the ground available for pasture to drink. With a lighter application of heavier droplets, the nutrients are absorbed faster and there is less foliage contamination, meaning cows can be put back to paddocks for graising sooner.