28 March 1997



SILAGE clamp maintenance and repair are increasingly important to prevent accidental pollution of watercourses with silage effluent.

Ayr-based Scottish Agricultural College building consultant Mike Kelly says that heavier machinery used to ensile wetter crops more rapidly is putting more pressure on clamps which were never designed to cope with such loadings.

He suggests that the keys to avoiding clamp failure are in managing the crop so that clamps are not overloaded with wet material. And in attention to detail when maintaining clamps before silaging begins.

"Before ensiling a thorough inspection of walls, joints floors drains and effluent tanks must be made to identify essential repair work. Enough time must be allowed for repairs to be made, especially where concrete is to be laid which will take 28 days to cure," says Dr Kelly.

Dr Kelly identifies leaking floors as the main problem with erosion of the concrete surface or the concrete joints.

"Where erosion has been severe aggregate stands out which can lead to lameness in cows in self-feed clamps," says Dr Kelly.

This should be ground down using a pneumatic scabbler before a silico-fluoride hardener is applied to the surface.

"Often a new floor is needed and it may be possible to overlay the existing floor with a new concrete floor, concrete screed or hot rolled asphalt."

He advises that a concrete floor overlay should be 100-150mm thick and that the old silage floor should be cleaned and allowed to dry before concreting begins.

"It should then be blinded with a levelling layer of sand, and covered with a polythene sheet before concreting."

An alternative to concrete is to use asphalt. This requires no expansion joints and only 24 hours to cure. It is resistant to acid and can be laid in a day but needs specialist contractors to carry out the work.

Aberdeen-based SAC consultant Hugh Campbell says that after leaking floors, the main causes of clamp failure are leaking joints, over stressed walls and inadequate effluent tank provision.

"Eroded sealing joints are a common cause of effluent leakage and must be sealed before ensiling," he says.

He recommends that to reseal a joint it must first be cleaned of the old sealant and effluent.

"Walls and joint must be vertical and clean to ensure a good bond."

He suggests hiring a crack router available to clean and prepare the joint and making the new joint 25mm (1in) deep and slightly wider than the old joint.

"A neoprene/polythene strip is then put in the bottom of the joint and the sides are primed before sealant is gunned into the joint. The sealant should not stand proud, or it will be torn out as soon as the loader enters the clamp."n


&#8226 Walls and joints.

&#8226 Floors and drains.

&#8226 Effluent tanks.

More than maintenance needed here.