Using agricultural stretch film effectively:

On large agricultural operations or smaller farms, agricultural stretch films have become indispensable in modern working life. They are used in various areas, particularly in the preservation and storage of feed. Especially in the production of silage, such as in the form of round bales, they play a key role in maintaining feed quality. Zill will show you which important guidelines should be followed when using agricultural stretch films to ensure that the wrapping process runs efficiently and long-term storage is successful.

Proper handling of agricultural stretch films

The correct storage of agricultural stretch films

In general, new and partially used rolls should be stored in their original box and kept upright. Additionally, the storage area must be dry and protected from heat and direct sunlight to ensure that the stretch films retain their functionality.

Important considerations before wrapping with agricultural stretch film

Before starting the wrapping process, it’s important to ensure that the ideal stage of feed is reached. This includes:

• Grass at the beginning of the heading phase
• Alfalfa in the young, less woody stage
• Clover at the budding stage

Wrapping too early or too late will negatively affect the energy content. If wrapped too early, the feed will have reduced nutritional value and low sugar content. A late, woody stage leads to an increase in trapped air, poorer feed preservation, and reduced digestibility. Less sugar and increasing fiber content will hinder the fermentation process, ultimately worsening the silage quality.

Also crucial is the dry matter content (DM content). Ideally, it should range between 35% and 55%.

A DM content < 35% can lead to the following consequences:

• Incomplete fermentation, especially since the sugar content is low
• Unevenly shaped bales
• An increase in (possibly toxic) leachates, leading to a loss of nutritional value
• More difficult and unstable storage
• Overall poorer preservation

A DM content > 55% can lead to:

• Loss of sugar
• Altered fermentation
• Increased risk of mold formation

It is also important that the cut is not too low during wrapping: A cutting height of 7 to 8 cm, or at least 10 cm for alfalfa, is considered the minimum. If the cut is too deep, dirt is more likely to enter the feed, regrowth is delayed, and the protective shading of the soil is reduced. This, in turn, promotes evaporation and can significantly decrease soil moisture.

Preparation and maintenance of the wrapping machine

In addition to proper maintenance of the wrapper, the following should especially be checked:

• The wear condition of easily worn parts, such as springs, bearings, rollers, gears, and cylinders.
• Proper lubrication of all elements that require greasing, such as chains, gears, and couplings.
• The rotational speed of movable elements, including the wrapping plate and arms.
• The cleaning of the pre-stretch rollers, which must be free of any adhesive residue.
• The height adjustment of the pre-stretch system to ensure that the roll and bale are aligned on a common axis.
• The system setting of the pre-stretcher to achieve a film stretch of 50% to 70% for round bales and 55% to 65% for square bales.

To check the degree of pre-stretching, follow these steps:
Draw two vertical lines 10 cm apart on the roll before stretching. Once the film is stretched onto the bale, the distance between these lines must not be less than 15 cm or more than 17 cm for round bales, and not less than 15.5 cm or more than 16.5 cm for square bales.

Pre-stretching is an extremely important component when using agricultural stretch films. If the stretch is too weak, it affects the correct adhesion of the film layers and risks air entering the bale, compromising the preservation. If stretched too strongly, the film becomes too thin and narrow, losing its optimal effectiveness and is at risk of tearing.

Feed baling

For the wrapping film to be applied correctly, the pressed bales must, among other things, be uniform and consistent in shape, as well as have a good press density. The requirements for this are:

• A symmetrically shaped swath
• A press set according to the manufacturer’s specifications
• Appropriate operating conditions, such as a good compression level and a consistent, adjusted speed.

Failure to meet these conditions risks the film tearing during or after wrapping.

The wrapping process with agricultural stretch films

Generally, each bale should have at least 6 layers of film at every point. In addition, the following considerations should be made:

• For coarse feed like alfalfa, at least 8 layers of film should be applied.
• When wrapping continuously, be sure to add 2 extra layers for the transition between bales.
• If strings, nets, or grass blades get caught between the first two layers of film during wrapping, two additional layers must be added to the affected bale until it is sealed airtight.

Make sure the film layers overlap sufficiently during the wrapping process, ideally by at least 50%. This is the only way to ensure a continuous, airtight seal that reliably protects the feed from oxygen and external elements. A poor overlap may result in improper silage preservation and quality loss.

Note that 750 gauge films offer better overlap than 500 gauge films, which enhances both the bale sealing and feed preservation.

Also, check the cleanliness of the pre-stretch rollers and the pre-stretch settings during the wrapping process.

Handling and storage of the wrapped bales

Wrapped bales should be moved as little as possible, especially to avoid friction and impacts during storage and transport. Any handling means a potential introduction of air into the bale, which can lead to a loss of feed quality.

Any handling should occur within one hour after wrapping, or at the latest within 72 hours. Due to the air pressure inside the bale, any intervention between the second and 72nd hour risks compromising the airtightness of the film layers, negatively affecting feed preservation.

Make sure to use proper bale handling clamps or tools specifically designed for the task to avoid damaging the bales.

Round bales should only be stored on their flat side (“standing bales”). Bales with a high dry matter content (between 45% and 55%) should be stacked no more than three high, while bales with a lower dry matter content (between 35% and 45%) should only be stacked two high.

We recommend storing the bales near the operation on a solid, flat surface, preferably concrete or asphalt. Apart from the type of storage surface, bales should never be placed on areas where water can accumulate through holes, channels, depressions, or drains. The presence of water can cause the film to lose its oxygen- and water-barrier properties, which in turn leads to a reduction or loss of feed quality—and even the feed itself.

The film cannot withstand damage from animal attacks, such as those caused by birds, cats, foxes, and rodents. Therefore, all wrapped bales should be covered with a suitable protective net, such as the Polytec® bale protection net or Zill silage protection net, and stored securely to prevent rodent access.

Any punctures in the film allow oxygen to enter the bale and impair the preservation of the silage. Bales should therefore be regularly inspected for punctures or other external damage. If any punctures are found, they must be sealed with agrifol® special adhesive tape, and the feed, if still suitable for feeding, should be used up as soon as possible.