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NEWS MESSAGE
Success factors for perfect quality silage
Part three with the most critical issues
Many factors need to be taken into consideration for achieving optimum silage quality. In addition to grassland care and fertilisation, which have already been dealt with, there are a number of points that need to be considered during and after harvesting. Today you can read the final section in our three-part series:
- Cutting time and mower technology
- Harvest
- Storage and silage quality
1. Clamp layout
There are different methods of building a clamp. In some countries it is normal to locate a clamp in the field. This offers the advantage that transport distances between the field and the clamp are relatively short. The effort required for feeding is greater, however, because the silage has to be fetched from the field first. In some countries, though, it is not permitted to form a silage clamp on open ground without a foundation.
Where the clamp is built on a foundation, there are two designs possible: with or without side walls. A clamp without side walls takes up around 20% more space since the heap is flatter around the edges. There is also a greater risk of tipping over the loader wagon and vehicle used for compression. Investment costs can be saved to a certain extent, however, and the size of the clamp can be varied more or less according to demand.
The following guidelines need to be observed:
- Width of clamp
The clamp should be at least wide enough so the loader wagon and vehicle used for rolling can pass each other (generally at least 7 metres). This is especially important where high capacity loads are being brought in because otherwise time is lost when the tractor used for compression keeps having to leave the clamp. The clamp must not be too wide though, because otherwise problems can be caused due to post-fermentation during extraction when a large area of silage has to be uncovered to gain access.
- Length of clamp
Both the length and width of the clamp depend on the quantity of silage harvested. The clamp should be long enough to allow the loader wagon to discharge its load in a single pass. The layer of forage should not be thicker than 50 cm in each pass. In practice this means that the clamp should be at least 30 metres long.
- Slanted side walls
In some areas clamps are built with slanting walls. This offers the advantage that compression is greater in the lower section and along the sides. However, building side walls like this is more complex and consequently more expensive.
In order to ensure good quality silage it is important that the clamp is covered air-tight. Proper fermentation can only take place if the silage material does not contain any oxygen. A plastic sheet should be placed along the side walls before the forage is delivered and the sheet then folded inwards over the top of the silage. At least two layers of plastic should be used to cover the clamp.
The first layer is normally a thin (usually transparent) under sheet. Then a thicker, usually white, plastic sheet is placed over the first layer. To protect the plastic an additional bird net can then be drawn over the whole clamp. This net is similar to wind-protection tarpaulins used in sheds.
Finally, the whole clamp is covered with sandbags. The sandbags should be placed close together around the edges and then every 5 metres or so across the whole clamp. In the middle of the clamp old car tyres or similar objects can be used to weigh down the covering material.
The clamp should remain sealed for at least six weeks after harvesting to give the fermentation process time to finish. At the end of this period the ph value should have reduced to the point where the silage remains stable.
Created: 15.06.2007
