FAQ barrier films and why not all that glitters is gold

Today, more farmers are being encouraged to use barrier films, which have gained popularity and appreciation within the agricultural industry thanks to their properties that help improve the quality and preservation of the crops.

The benefits of using “barrier” films -in this case to preserve forage- are multiple. However, farmers need to pay attention since it is becoming increasingly common to find plastic films on the market that claim to belong to the “oxygen barrier” type when in fact they don’t reduce, or block, oxygen transmission.

Additionally, one of the factors considered at the time to choose plastic films as an alternative is the investment that will be made, and at this point it is essential to be certain that you are acquiring what you are looking for because nobody wants to take home the wrong product ultimately resulting in a loss of capital both because of an inadequate product and an increase in wastage of fodder.

There are several barrier film options out of which the use of plastic barrier films that reduce the entry of oxygen is the most recommended as a way to increase farm profits. According to the article The importance of using Oxygen barrier films, this is basically a measurement to determine how effective the material acquired is when it comes to preventing oxygen entry.

It is worth mentioning that when the OTR factor is lower, the oxygen permeability of the plastic will also be lower, which will allow to achieve better results. What is paramount to protecting the quality of forage is to avoid as much as possible that the oxygen flows through the first meter of silage pile.

Expert opinion about barrier films:

To know all the details about plastic barrier films, we talked to Daniel Fiersbach, Animal Nutrition expert, to clarify the most frequent doubts about these plastics:

• What is gas permeability?

It is a quality of plastics that can be measured in cm ³/m² x d x bar, which translates into cubic centimetres (cm³) divided by square meters (m²) per day and at a specific pressure (normally 1Mpa). To get an idea about this, let’s imagine a lump of sugar that is usually 1 cm³ in size. The permeability of gases of the PELD will be proportional to its thickness, in other words, the thicker the film, the less permeable it is, and the less gases will pass through it.

The recommendation of the Association of Farmers of Germany (DLG) is that the value in a silage film does not exceed 250 cm ³/m² x d x bar, that is, no more than 250 lumps of sugar, representing the gas, would pass per m² of plastic in one day.

• What are barrier films?

They could be defined as those films that include the capacity to be permeable to gases below 10 cm ³/m² x d within their qualities. These values are achieved through the EVOH or PA polymers. In general, films with a permeability higher than 10 cm3 would not be considered “true” barriers. If we consider the lumps of sugar as an example: it is not the same passing 125 lumps than just 10.

• Can I distinguish barrier films from regular plastics?

It’s not possible at first glance. The EVOH or PA layer is much thinner than a human hair and has the same colour as the rest of the plastic. However, there are indications that may be helpful to distinguish one from another, although there is no guarantee:

Price: Barrier films tend to have a considerably higher cost than regular films.

Layers: They are usually made with five additional layers, 3-layer-films with barrier effects are not frequently found.

We also recommend you read other articles related to the storage of food or agricultural products such as advantages of silo bags vs. traditional silage and how to minimize mycotoxin problems storing animal food.

What are the effects of barrier films on fodder?  

Other doubts usually arise about this type of plastic films that are used as barrier films in planted crops worldwide, that explains why several conversations have taken place through digital platforms, such as YouTube, in an attempt to clarify the majority of those questions referring to true “impermeable” barrier films versus versions of semi-barriers or standard plastics. 

The topic of barrier films and their effects on fodder was discussed on a recent webinar since it is one of the recurring concerns of farmers, who are always eager to find viable alternatives that help them minimize money losses as a result of spoiled silage, which not only must be disposed of right away after packing but also decreases the nutritional value of silage, compromising its integrity. 

Below are some of the most common doubts regarding the current situation in terms of the nutrition and management of food silage for farm animals, as well as the most common problems related to silage management and food storage options, among which stands out the animal feed made from the combination of organic and inorganic substances obtained from products with vegetable and animal origin.

Finally, we will get into detail on how barrier films are one of the best options to maintain animal feed quality and properties. 

Certainly, several types of plastic films can be found on the market, but is it advisable to use a thin protective film also called underlayer or clampsheet or, a version that combines a protective bottom layer and a silage film all rolled up together? 

One of the recommendations that are usually made to farmers is to try to always use a white on black bunker cover since this sheet reflects better sunlight, reduces temperatures and usually is made of premium resins specially UV treated to ensure on field duration and performance. 

A good alternative, which has proven easy to handle, is to combine together a white/black bunker cover and an oxygen barrier film to both physically protect the silage and also control the fermentation process and nutritional value of the fodder. 

In more northern areas, some farmers use a black on black bunker cover as the impact of sunlight in summer is not something critical to the build of heat under the plastic. So, it is important to know the environment to choose the best cost-effective options available.  

Nevertheless, before committing to large investments or radical changes in operations, it is always best to proceed through trial and error of comparing different systems and technologies available.  

What is the recyclability of a barrier film? 

In today’s growing concerns over sustainability and circularity, a common question is what of the recyclability of the barrier film once it’s use has expired, or are there special levies compared to non-barrier plastic films. 

The recyclability will depend on the type of barrier film used, as each film is made from specific materials and different components that may make the product not suitable recycling. It is important to know which barrier products have been built into the plastic since some films are one hundred percent recyclable, while others must be discarded entirely since they cannot be recycled and have to be destroyed. 

On the other hand, certain countries have specific collection schemes established for plastic waste on farm and different levies are applied depending on the recyclability of the plastics. It is important that farmers enquire about existing Legislation and environmental protection practices. 

How does the colour of plastic films influence the results? 

There are some differences regarding the different colours of plastic films that can be found on the market and everything will depend on the silage requirement and the climatic characteristics of each region of the world. 

For example, using black/black silage films means a greater absorption of sunlight, so the heat inside the silage, under the plastic, increases considerably while on the contrary using films of other colours, such as white/black or green/black, provides lower heat levels and a more controlled fermentation process. 

There are regions such as South Africa where white/black plastic films are generally used, so temperatures of about 60 degrees Celsius can be easily reached, causing the protein within the silage to begin degrading faster. Some farmers alternatively will use the white/black or black/white surface depending on the type of fodder and month of the year they are ensiling.   

What is the probability that the barrier effect will decrease? 

Another question that usually arises in conversations with farmers is whether the barrier effect of the plastic is reduced/lost over time. This of course depends on the type of plastic used. Some plastics do not include true barrier properties to Oxygen and are basic physical barriers that reduce air pockets between the pile and the outer cover.

These plastics of course lose their physical properties over time. Other plastics have built-in barrier products that are resistant to time and usage and should not lose their properties until the plastic is disposed of. 

It is also true that, even if an excellent quality barrier film has been chosen, it will certainly be affected over time and by the incidence of UV rays that will gradually degrade it along with its barrier effect. In any case, it is advisable to avoid storing the silage for more than 12 months to guarantee the quality of the silage product. 

Does the thickness of the silage covers directly affect compaction? 

Nowadays, we could say that is not the case, as contractors and farmers are much more aware of the necessary compaction that is usually carried out by heavy machinery driving of the pile. Before the silage piles were weighed down with heavy plastic tarps and tyres. Today, more efficient solutions are available to ensure a better fermentation process and preservation of nutritional values of the fodder. 

How long can silage covers quality be maintained? 

It will all depend on the quality of the plastic used and how it is handled during the years of use. There are cases of silages that have lasted about four years and, although there were some losses caused by wear on the upper layers of the plastic, they have achieved their goal, so establishing a maximum number of months or years can be relative. Their durability, be it greater or lesser, will be related to how they are handled and how the silage compaction process is performed. 

Plastic films allow to store and extend the useful life of seeds and food that will later be consumed by livestock. Most reputable manufacturers ensure UV protection for 20-24 months on-field use. This is probably also the maximum recommended storage time for feed and grain being common practice worldwide the storage of not more than 6-12 months. 

Many workers in the livestock industry agree that it is better to invest in quality silage plastics to prevent environmental or pathogenic factors such as mycotoxins from directly damaging the food and the animals as well. 

To learn more about this topic, we recommend reading our articles on best practices for milk production and why is hay bale density important to improve livestock nutrition?