Baled silage makes for better ground conditions

By Dermot Forristal, Teagasc, Crops Research Centre, Oak Park, Carlow.

Baled silage, because of its lower weight offers better scope for achieving lower ground pressures suitable for very difficult conditions.

While the equipment associated with the baled silage system is lighter than trailer-based harvesting systems, the weights are still considerable:

• 100 HP 4WD tractor: 4.5 t
• Chopper baler with bale: 3.0 t
• Wrapper with bale: 2.3 t

All machinery operations from mowing to bale transport should be considered when looking at ways to reduce field damage. Where possible, use light tractors and plan all operations in advance. Baled silage is often used as a fire brigade measure, which doesn't allow its full potential to be exploited.

Balers

Balers are fitted as standard with small 10-15 or 11-15 tyres, which are 250-300 mm wide and 760-840 mm in overall diameter (see Table 1). These are only suitable for use in very dry soil conditions.

The normal `oversize' tyre offered is usually a 15.0/55-17 tyre, which is about 400 mm wide with an overall diameter of 850 mm. Although this tyre is wider, it is not adequate in wet conditions.

Wider, large-diameter tyres are necessary for a substantial improvement e.g. 500-22.5 or 17.5-24 (500 mm wide, 1200mm diameter) or even bigger. In many cases, this will require some modification to the baler's axle and/or side guards, but an enormous benefit in trafficability can be expected.

Wrappers

Bale wrappers are also poorly equipped with tyres. Of more significance, however, is that their current design restricts the tyre options to relatively small diameter tyres. A 15.5-15 tyre may be an option where 11-12 or 12-12 tyres are fitted as standard. Wrappers need not be in the field however.

Tractors

Tractors and their tyres are a major source of damage. Baler tractors weighing in excess of 4 tonne should be fitted with tyres capable of operating at less than 0.8 bar pressure when loaded. As a minimum, 540 mm, or preferably 600 mm, wide rear tyres should be selected.

Wider tyres should even be considered. While the use of 4WD tractors has improved mobility in wet conditions, if they are not fitted with suitable tyres, excessive damage can be caused.

Tractors hauling bales on rear-mounted bale transporters should also be equipped with good wheel equipment.

Many options are available, including dual wheels. While tyre width effectively reduces ground pressure, large diameter tyres are particularly useful when the tractor moves through a very wet area, as they tend to climb out of the rut being formed.

Where self-loading bale trailers are being used, very large tyres should be fitted, particularly to those carrying in excess of 3 or 4 bales.

Driving patterns

Good driving practice with baled silage operations can help to reduce soil damage. Always try to cut the wet patches while travelling downhill.

If there are wet areas on the turning headland, try and arrange the `sets' so that traffic on these areas is minimised. It is useful if the mower width allows for the mowing tractor and baling tractor to travel in different wheel tracks; wider (3.0 m) mowers help this.

In wet field, the bales should be transported before wrapping, as this will at least eliminate the wrapper as a source of damage.

If sufficient transport capacity is not available to move the bales to the point of storage, they should be moved to a dry area of the field for wrapping.

If field wrapping in wet soil conditions is unavoidable, movement of the wrapper with a bale on-board should be minimised.