Bale Wrap Usage Guidelines
We have put this guide together to help you calculate how much bale wrap you need. The following table shows the approximate use on varying sized bales in different crops. These figures are given as a guide only.
4' silage / haylage round bale
|Film Specification||6 Layers||4 Layers|
|500mm Wide x 1800m Long||17||26|
|750mm Wide x 1500m Long||22||33|
Mini silage / haylage bales
|Film Specification||6 Layers||4 Layers|
|250mm wide x 1800m Long||20||30|
How to calculate film usageThe number of bales that can be wrapped from a single roll of bale wrap can be accurately calculated, provided the following points are adhered to:
- THE BALE SIZE IS 1.2m X 1.2m AND OF UNIFORM SHAPE
- THE WRAPPER IS CALIBRATED FOR THE CORRECT NUMBER OF TURNS
6 film layers 36 turns (500mm) or 24 turns (750mm)
- THE FILM IS ACCURATELY AND CORRECTLY STRETCHED TO 70%
In order to ensure good high quality silage bales, certain important requirements must be met.
Uniform and well shaped balesIt is vital to ensure that bales are firm, tidy and well secured. This is of particular importance when wrapping net wrapped bales as poor bale coverage by the net, resulting in 'shoulders' on the bale, will allow air to become trapped within the area between the ’shoulders’ , leading to spoilage and crop loss.
High dry matter balesHigher Dry Matter (DM) bales ensure good crop fermentation and also help wrapped bales maintain their shape after compression, aiding bale storage.
Wrap within two hours of bailingExtended wilt times will encourage the formation of fungi and will also reduce the nutrients in the crop.
Wrap correctlyAlways ensure correct film application, ideally a MINIMUM of 6 layers (essential on Haylage crop), with a MINIMUM 50% overlap. To guarantee correct film application and overlap, film stretch must be controlled to the correct maximum of 70%. An increase in film stretch causes excessive film ‘neck-down’ leading to reduced film overlap. This can be avoided by always ensuring the pre–stretch rollers are clean and free from tack build up. It is also important to maintain correct turntable speeds, particularly when wrapping in higher ambient temperatures.
Remember – where a bale exceeds 1.2m diameter the wrapper cannot provide a minimum 50% overlap without increasing the number of revolutions of the bale. This will also apply when wrapping mis-shapen bales.
Store bales correctly
- Very often the prime cause of crop spoilage is poorly stored bales.
- Wrapped bales should ideally be stacked on their ends, allowing the maximum layers of film to be in contact with the ground for added protection and eliminating the possibility of bales becoming mis–shaped by further stacking on top.
- Low DM bales should never be stacked more than one layer high. This will avoid the seal on the film overlap
- opening through the constant heavy pressure exerted on them from bales on top.
- Always store wrapped bales away from trees to avoid bird damage. Never leave wrapped bales out in the field for extended periods after wrapping, as this too could encourage bird damage.
- Always cover the completed bale stack with Novatex Silage Net, a close–weave raffia type net on a roll. The net should be suspended off the bales’ surface by old tyres (or similar) and weighted down at the ground.
- When a bale becomes damaged cover the hole generously with silage repair tape, ensuring that the silage film is clean and dry and dust free.
Poor quality crop
- Crop not of optimum quality for cutting.
- Grass contaminated by soil due to mower setting too low.
- Grass contaminated by dung from recent grazing.
- Extended wilting period allowing quality of crop to deteriorate.
- Poor shaped bales, with ’shoulders’ allowing air to become trapped during wrapping.The use of a net, which can guarantee full width bale coverage,should avoid this.
Film Layers opening
- Low cling properties of the film used. Maybe the film is out of date.
- Insufficient layers of film applied.
- Crop, netwrap or twine protruding between layers preventing a good seal.
- Uneven film overlap on bale. This can be caused by :
- Incorrectly calibrated wrapper.
- Insufficient number of turns of the bale (minimum 16 turns for 750mm film or 24 turns for 500mm film on a 1.2 x 1.2m bale for a four layer coverage. For a six layer coverage turn bale 24 turns using 750mm film or 36 turns for 500mm film.)
- Oversized or misshapen bales, where the greater circumference of the bale will require extra turns
- to ensure the correct overlap of film.
- Film overstretches often caused by over tacked pre-stretch rollers.
Film SplittingDamaged film used during wrapping, causing it to tear when stretched
Insufficient film appliedMost often found in the area of the bale ahead of the last film applied, signifying the need for another turn of the bale during wrapping. Also, remember the first half turn of the bale is required to bring the film up to its full width on application to the bale.
Film Over–StretchOften caused by poorer quality film in higher ambient temperatures, excessive turntable speeds when wrapping or over tacked pre–stretch rollers causing an increase in film ’neck–down’, leading to reduced film over-lap.
Bird damageUsually very easy to identify, holes through all layers with crop pulled up through the film. Usually these holes are found on bale tops only, though can occur at ground level when bales are left in the field after wrapping. This can be avoided by using Novatex Silage Nets.
Punctured filmOften caused by wrapping crop with very high dry matter (DM), or when bales are ejected from turntable directly onto dry grass stubble. For best results, always wrap in the same area of the field to allow all bales to fall on to a smooth area on the ground.
Film Breaks when wrappingIf film breaks when wrapping, a close examination of the film break profile will help to identify where the break began. From this, the cause of the break can often be traced back to either the roll, the bale or the film catching on the wrapper, depending where the break began.
The diagram below illustrates this: