Several new additions to the baled silage marketplace will reduce bale spoilage and the number of decomposing bales that can leak effluent into the soil and water tables close to the ground surface.
There have been some other advances by some manufacturers such a five-layered film and film-on-film technology and 3D wrapping, all of which are good for the environment.
A new stretch wrap film has been developed overseas and for the past couple of seasons tested under Australia's high ultra-violet (UV) light conditions.
This film contains the oxygen-barrier (OB) technology, which has been available for stack silage in a one-step or two-step system for several years now.
The OB layer is made from food-grade plastics. It's a patented film with a layer of impermeable plastic (ethyl vinyl alcohol, EVOH) sandwiched between layers of polyethylene (PE).
The OB technology has finally been successfully integrated into stretch-wrap film manufacture and available to farmers and contractors this season.
This new OB film is nearly a 100 times more effective as a barrier to oxygen permeability than PE films.
It will prevent loss of gases into the atmosphere, which does occur in the older films and at a greater rate as those films age or if not enough is applied at wrapping.
Farmers using the film have also commented that they cannot smell anything near the OB wrapped bales compared with the traditional films, obviously from gas seeping through the film.
Admittedly if the new film is punctured, the seepage will still occur.
The OB stretch wrap film is more expensive than the traditional wrap but some on-ground measurements have reported reduction in dry matter losses of more than 40 per cent (from 7.7 per cent down to 4.6 per cent). When the "saved" silage is fed to animals, instead of the silage being lost or spoiled and/or reduced in quality, the benefits should outweigh the higher cost.
There is still slight oxygen permeation into the bale but is almost negligible so almost nil aerobic deterioration, which also results in almost negligible or nil yeast and mould growth due to little air entering the bale after wrapping.
Film-on-film plastic Another new technology is referred to film-on-film where a plastic film replaces the traditional net wrap; the bale is then stretch wrapped with PE plastic. This technology maintains the pressure on bales after the plastic is placed on its perimeter and avoids the release of tension as often occurs with netwrap, which allows air, the enemy of silage, to enter the bale before stretch warp is applied.
3D wrapping An alternative system referred to as 3D wrapping applies stretch wrap film to the individual bale perimeter before then applying the outside layers. This is cleverly achieved by a 90-degree rotation of the same wrapping arms on the machine. However, the bale is netwrapped first, so no saving there.
Research comparing four or six layers of film with the 3D wrapper programmed to wrap at least four or six layers over the whole bale surface found that the conventional wrapper consumed 0.696 and 1.013 kg of plastic per bale for four and six layers respectively. These bales had five times more film on the ends than that at the side.
The 3D wrapper utilised 0.862 and 0.976 kg of plastic per bale for four and six layers respectively.
The number of layers applied at the side and ends of the bale, was more uniform, allowing at least seven layers to be applied over the whole bale surface. The 3D system reduced the amount of plastic used by 4 per cent to 15 per cent in comparison to six standard layers, which is the recommended number of layers for ensiling stemmy lucerne, storing for more than two years and if transporting bales.
The perimeter and outside stretch wrap film are quickly and easily removed from the bale at feed out and relatively clean of forage matter so making recycling much less hassle for the farmer and the recycler.
Hopefully, this technology will encourage more farmers to recycle their used film.
The technology of silage stretchwrap plastic continues to improve each year so watch this space.
With the expense of growing, harvesting and feeding out bales, DM and quality losses need to be reduced at all stages from standing grass to harvesting to storage to feeding out.
Of course, the usual good practices of making baled silage are still essential such as cutting early in the season, wilted to the correct dry matter (40-50 per cent DM) content, sealed with the latest plastic technology and holes repaired as soon as possible with specific silage tape.D
*Senior dairy extension officer, Agriculture Victoria, Victoria
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