Teagasc: Silage-pit and effluent management

THIS year’s silage season will soon be upon us.

Farmers should ensure that silage storage facilities are fit for purpose. This means that the silage pit and silage effluent collection and storage facilities meet the standards required by the Department of Agriculture and Food (DAFM).

At the time of writing – under the COVID-19 restrictions – the DAFM considers that some limited projects that are essential for animal welfare should continue. Examples of works that are considered critical include work on silage pits (storage of fodder) or urgent calf housing.

Silage pits

Slabs and walls need to be structurally sound to ensure ensiling is completed in a safe environment.

Silage effluent-collection channels and tank storage must be capable of managing the volume of effluent generated.

Silage effluent is a highly polluting liquid and can cause fish kills in watercourses and rivers. It can also cause serious water contamination of wells if it is allowed access to them.

Now, while silage pits are empty, is the time to examine the silage slab, effluent tanks, channels, silo floors, walls and wall-floor joints channels for any maintenance and repairs needed before the pit is used again.

Silage slabs should be cleaned thoroughly (for example, power washed) to identify any problems. Slabs and channels must be leak-proof, and all silage effluent must be collected and safely stored.

Common defects in slabs include cracks that allow seepage through the concrete, and effluent channels being cracked or blocked.

Defects or problems should be rectified before silage making commences. If the pit is not fit for purpose, don’t use until all repairs are completed. For guidance, repair works should be completed to DAFM specifications for Concrete Silage Bases S128 and Resurfacing of Silo Floors S128A.

These can be obtained at www.agriculture.gov.ie

Making silage

It is important that you know how much silage your slab is capable of storing.

Take into account any remaining silage in the clamp following the winter and the capacity of the pit to store this season’s silage yield. A lot of the problems with effluent arise from farmers attempting to ensile more silage than the slab is designed to hold.

The edge of the silage clamp should not extend further than the effluent channel and result in seepage of effluent to the environment. All effluent should enter the channels under the cover of the silage polythene, and the edge of the ensiled grass should not extend onto or over any channel.

The open channel space is maintained by placing a plastic slotted drainage pipe in the channel. Ensure effluent is diverted to an effluent tank or slatted tank. Check any effluent tank levels on a daily basis when effluent is being produced and take action if necessary to prevent it from overflowing.

To prevent effluent from flowing out over silage walls in the few days following ensiling, it is important not to pile the grass too high over the walls and to slope the grass back at 45˚ from the top of the walls.

If the capacity of the silage slab would be exceeded due to the size a silage crop any additional silage should be stored on another slab or made into round bales.

Wilting of silage is recommended in order to raise the sugar content of the silage water fraction and improve preservation. This has the added benefit of reducing silage effluent.

Land spreading of silage effluent

When land spreading silage effluent, dilute the silage effluent with one part water/slurry to one part effluent. Do not spread if rain is forecast in the following 24 hours.

Don’t spread the mix within five metres of any watercourse, 10 metres where field slope exceeds 10 per cent, 20m from lake/main river, 25–200m from well/public water supply.

Round Bale storage Generally, round bales have higher dry matter content than pit silage and do not generate effluent.

However, where round bales are made in wet conditions, then these bales can generate silage effluent.

The effluent from round bales is treated the same as from silage pits and must be collected and stored in same way. Under cross-compliance regulations, silage bales should not be stored within 20m of any water body where there are no facilities to collect effluent.