Tower silo, round bale, tube or clamp silo?
The question of which method is best for conserving silage is a hot topic for debate. This can be considered from many different angles. For example, round bales have low capital costs, while a tower silo is a large investment. On the other hand, a tower silo is less labour intensive during daily silage handling throughout the winter.
There are clear differences between systems in terms of, for example, the work involved, capital costs, dry matter (DM) losses, and plastic consumption, so let's review each in turn.
Plastics consumption
The tower silo has the lowest plastic consumption, followed by clamp silo, tube silo and round bale, which uses about 4.5 kg plastic per ton/dry matter (DM) of fodder. Therefore, if the key ambition is reduce plastic use, then the tower silo would be the suitable option.
DM loss
The round bale has the lowest DM loss with about 4-5%, followed by the tube silo and the tower silo for which losses are about 7-8% DM. Clamp silo far exceeds these systems, with losses estimated to be as much as 15% DM, often more. If you have a shortage of acreage and need to save every crop that grows, the round bale system is the best choice. This approach also gives farmers the flexibility to harvest and store crops from different fields separately.
Capital costs
Capital costs are lowest for the round bales or tube systems, as they relate to little more than providing the correct surface on which to store the bales or tubes - it should be hard, smooth and without stones in order to prevent damaging the film.
Building a clamp or tower silo entails a larger capital investment. A tower silo requires less space, but the construction itself is more expensive. A clamp silo has greater alternative applications than a tower silo, but towers do have a reuse value as they can often be can be taken down and sold if no longer used.
Labour requirements
Labour requirements are fairly similar between the various systems. They depend mostly on the distance between the field and the storage area, and on the size of the equipment used for harvesting. Most differences in labour requirements stem from silage handling for feeding, a daily routine throughout the winter season. The labour requirement is largest for round bale silage where the stretch film is often removed manually. The clamp silo and tube systems also require handling with a tractor. The tower silo, on the other hand, can be mechanized so that a push of a button will provide fodder straight to the feeding table.
What is the most economical system?
It is apparent that there is no easy answer to the question of which silage storage system is the best, as no system offers the optimal benefits from all points of view. Naturally, it is possible to try to define an overall cost taking into account labour, capital investment, cost of plastic and DM losses. But to come up with a generally applicable cost for all these components is not feasible - it is something that each farmer must calculate based on their own assumptions and on-farm conditions.
In a recently published doctoral thesis* by Carina Gunnarsson at the Swedish University of Agricultural Sciences, an attempt was made to compare costs for harvesting and storage in round bales with a clamp silo if a loading wagon or self-propelled chopper is used. In the report, a farm with 70 ha of forage was used a basis for the calculation, taking into account all harvesting and storage costs.
The results for the clamp silo system - considering equipment, labour and time costs - were estimated to be 0.34 SEK (0.034 EUR) per kg DM when a loader wagon was used. Costs for the round bale system were estimated to be 0.38 SEK (0.038 EUR) per kg DM.
When adding storage costs such as the clamp silo, plastic sheeting, netting and stretch film, the cost was indicated to be about 0.55 SEK (0.054 EUR) for clamp silo and 0.60 SEK (0.059 EUR) for the round bale system. When adjustments were also made taking into account DM losses, the costs were 0.67 SEK (0.066 065 EUR) for the clamp silo systems and 0.65 SEK (0.064 EUR) per kg DM for the round bale system.
In conclusion, one can say that harvesting, storage and DM loss costs balance out one another and the total cost is comparable for clamp and round bale silage. Not included is the cost of silage handling at feeding time. Also to be considered in the evaluation of any system is the flexibility offered by round bales, which allow separate storage of different crops and quality harvests. It should also be remembered that round bales are easy to handle and transport.
*Report, in Swedish, available here
| Rolf Spörndly, Swedish University of Agricultural Sciences (SLU) |
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