Clamp Management

Clamp Management

Good Clamp management is essential to producing the best quality feedstock. Research shows that the average clamp in the UK loses around 25% of its digestible dry matter – the only part with any energy value. Good clamp management is essential to preserve as much of the feedstock’s dry matter.

A large part of these losses will be invisible, primarily in the form of carbon dioxide and water. The losses come from the most digestible part of the silage, rendering a greater proportion of the feedstock undigestible. As it is the more structured part of the plant material that remains more or less intact, the losses are less noticeable as the volume of forage in the clamp appears unchanged.

By employing good clamp management practices as part of your whole forage preservation regime you can help reduce dry matter losses and, thereby, retain more energy in your feedstock.


  • Clean out any debris left from previous silage and thoroughly clean the walls and floor of the clamp space.
  • Make sure there is suitable drainage for effluent.
  • Line the walls with side sheets. This is imperative and a good seal will not be possible without using them. They also help protect the walls of your clamp.
  • Make sure the access to the clamp is clear of debris and cleaned, even during clamp filling.

Clamp Filling:

  • Fill quickly and evenly, but only in layers of up to 15cm in depth – any greater than this and good consolidation will be difficult to achieve.
  • Pay great attention to consolidation. It cannot be overstated how important it is to do this well. A density of about 750kg/m3 fresh weight (220-250k/m3 dry matter) should be the minimum target.
  • Do not re-roll the next day.
  • Do not over-fill the clamp. Compaction above the walls is at least 10% lower than if the silage is level with the walls.
  • Use a SilaPactor to achieve up to 40% greater compaction.

Sealing the Clamp:

“Maize silage trials showed a ONE day delay in sealing the clamp resulted in an EXTRA 27% loss in organic matter in the top 45cm, compared with a clamp sealed immediately. (Nutcher et al, 2015)

  • Seal the clamp as soon as consolidation has been completed. For best results use O2 Barrier 2in1 sheeting. Remember: anywhere where the sheeting is not touching the forage is an air gap. It is not good enough just to be an oxygen barrier, the sheeting needs to mould to the silage to prevent air pockets.
  • Ensure the thinner oxygen barrier layer goes tight up to the shoulders and weigh down with gravel bags tight to the edge. When using O2 Barrier, allow the sheeting to overlap the walls and fold it back over the gravel bags, along with the side sheets, applying a further row of gravel bags to hold them in place. This keeps a tight seal at the most vulnerable part of the clamp, the shoulders, and also prevents rain running down the sides of the silage.
  • Ensure the sheeting over the whole clamp is is weighted down to prevent billowing. This can be done with gravel bags and gravel belts or by using Clamp Mats or tyres.
  • Cover with a protective netting layer to protect from birds and vermin, again weighing this down. Alternatively use the full surface-tensioning mesh cover, Silage Safe.

Opening the Clamp:

  • On opening, cut back the sheeting fully from the face, exposing as little as possible of the top surface.
  • Weigh down the leading edge with gravel bags attached to gravel belts.
  • Do not cover the face again once it has been opened.
  • Work across the face in an orderly manner, aiming to keep the surface as flat/level as possible. The greater the surface area created, the greater the exposure to air for the feedstock and the greater the risk of aerobic spoilage.
  • Used correctly, Safesil will prevent ANY heating at the clamp face. More about Safesil.

And finally…

Silage additives are not a replacement for poor practices – they are only effective when combined with good clamp management. There are many external pressures placed on a business over which you have no control, therefore, you have to look to control those areas where you can have an impact. Clamp management and the preservation of the energy value of the feedstock is one such area. It is key to getting the most from your feedstock and, in turn, improving digester performance.

For more detailed information on forage preservation and clamp management contact us.

We can also offer free, bespoke training sessions for your team working on the clamp.

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Would you like more information?

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