Controlling silage effluent & nutrient value

I WROTE in a previous article about the key drivers to making quality silage such as sward type, fertiliser application, cutting date, etcetera.

While the main focus is growing and producing top-quality silage, our attention should also turn to the actual silage pit.

While silage pits are empty, now is the time to ensure that silage pits and storage facilities are fit for purpose. This means that the silage pit, silage-effluent collection and storage facilities meets the standards required by the Department of Agriculture, Food and the Marine.

To prepare the silage pit, first clean the pit and effluent channels with a pressure washer. Once your pit is clean, it will be easier to identify and repair any cracks or broken concrete.

Silage effluent has a corrosive effect on concrete floors and walls so an annual inspection should take place about a month before silage cutting.

All repair works are to be completed in accordance with the Department of Agriculture

Specification S128 and S128A, which can be viewed on the Department of Agriculture website.

Once your pit and effluent channels are fit for purpose, you can proceed to ensile the silage. When making silage ensure all silage is ensiled inside the channels to enable effluent to be collected and directed into the effluent tank.

Farmers will always look for the opportunity to make extra silage. This surplus silage should be stored in another suitable pit or made into bale silage if you do not have sufficient capacity in your main pit.

Also ensure you have enough effluent storage capacity to deal with extra silage as most of the effluent flows in the first two weeks, but will continue to flow for many weeks after that too.

Silage effluent contains nutrients N, P and K, so care must be exercised in spreading effluent on land to ensure it does not run off.

Ideally, check the weather forecast and do not spread when rain is forecast within the next 24 hours. When land-spreading silage effluent, dilute the effluent with one part water or slurry to one part effluent, and do not spread within five metres of any watercourse.

To avoid scorch, the effluent should be spread on bare ground. The most ideal field is where the silage has been cut, as the effluent will replace some of the nutrient off-take from silage harvesting.

Pollution is something in the wrong place, at the wrong time in the wrong amount. Silage effluent can cause pollution if not managed correctly. Silage effluent has a high Biological Oxygen Demand (BOD), meaning it will use up oxygen in water with detriment to organisms such as fish.

Big bale silage is an alternative for many farms and should be stored on a smooth, well-drained site, as this will aid bale removal in winter.

There is little or no effluent produced from bale silage as the crop is wilted to 30 to 35 per cent Dry Matter before baling.

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

Silage bales may not be stored outside of farmyards within 20 metres of rivers or a drinking-water abstraction point in the absence of adequate facilities for the collection and storage of any effluent that may arise.

Department Inspectors will check that Silage effluent is managed in a way that prevents pollution under cross-compliance regulations and is not spread during the prohibited spreading period.