Do You Know Where Your Effluent Is Flowing?

Silage effluent is one of the most potent sources of pollution on the farm.

It is 200 times more polluting than untreated sewage. Hence it is very important to ensure that no effluent leaks from silos and associated tanks. Effluent starts to flow within a few hours of grass being ensiled, peaks within two days and can continue for several weeks. Directly ensiled grass can produce a peak flow of about 30 litres per tonne per day. A common mistake is underestimating the volume of effluent that will be produced, and failing to check the collection tank in time.

Silos should be routinely inspected for effluent leakage. Signs of leakage include scorched grass in the vicinity of the silo, silage effluent odour and discolouration or the appearance of froth, foam or fungus in rivers or drains following silage making. All effluent channels must be watertight and free from obstructions, for example, silage or silo covers which will impede the flow of effluent to the collection tank. Diversion systems should be checked to ensure they are working and set to deliver effluent directly to the collection tank. When filling the silo all silage must be kept behind the front channel so that all the effluent is collected.

To minimise unnecessary collection of clean water run-off from the silage cover extend the polythene sheet over the effluent channel when sealing the pit. Run-off from flash floods should be diverted away from the silo to ensure it does not enter the effluent collection tank, causing it to overflow. Maintaining spoutings and downspouts on nearby buildings can significantly reduce the volume of effluent to be collected.

For further advice on silo management or any aspect of farm waste management, contact Countryside Management Staff at your local DARD Office.