The use of plastic mulch in berries

Production of berries can be done in many ways depending on the scope of the business. Still today many traditional methods persist together with more sophisticated technology of mulch, hydroponics and walk-in tunnels .

During the past decades, the “mulching” technique consisting on placing a plastic cover over the soil has been perfectioned in different berry crops, firstly aiming to reduce the evaporation of irrigation water by improving moisture retention, in addition to preventing the fruit from making contact with the soil, and then increasing the precocity of the crop, protecting the initial stages of the crops from disease and improving the homogeneity and quality of the fruit.

The films used for plastic mulch are simple applications that nevertheless are of great importance in agriculture, since they increase the temperature of the soil when required, reduce the use of chemicals and pesticides and protect the soil structure as well as avoid erosion.

Plastic mulch film made of polyethylene (PE) is one of the most commonly used, it can be customized for specific applications/crops by using different colours and thicknesses (from 0.4 mil (10mic) to 6mil (150 microns).

In addition to the objectives already mentioned, plastic mulch (PE) is 100% fully recyclable which also helps to reduce the impact on the environment. In this sense, today’s developments in BIO degradable mulches continue to provide efficient solutions for the farmers.

Use of plastic mulch on strawberry crops

A recent study conducted by an interdisciplinary team of researchers from three universities in the United States (the University of Tennessee, Washington State University, and Montana State University) consulted a group of 227 strawberry planters – especially those who produce berries for fresh markets- regarding the use of plastic mulch films.This survey, which obtained funds from the US Department of Agriculture through the Specialty Crops Research Initiative (SCRI) program, was intended to measure not only the use of these polyethylene mulches but also the potential to use the technique with biodegradable material.

Two-thirds of the respondents (64%) stated that they had fully or partially used growing techniques with PE mulch. 93% exhibited different levels of satisfaction with the use of this material and highlighted some advantages such as weed control (68%); cleaner berries (28%); moisture retention (15%); earlier production (10%); ease of use (9%) and increase in soil temperature (8%).

Those who answered that they had never used PE plastic mulch in their fields, argued that it was because of its conflict with existing practices of strawberry production (26%); high cost (23%); lack of interest (15%); environmental concern (12%); labour requirements (9%); absence of equipment to place the mulching (7%); lack of knowledge (5%) and the inability to reuse this mulch in multiple growing seasons (5%).

However, most of these arguments against the use of mulches in strawberry crops can be easily refuted precisely due to the great advantages mulch plastics offer. For example, the cost of the material is compensated by the savings involved in the irrigation of the crop, as plastic mulch helps to retain moisture; their use decrease the amount of herbicides need; and the improvement of the quality of the fruit yields  higher revenues when marketed; among many other advantages.

On the other hand, the manufacturing of plastic mulch films has become increasingly sophisticated with the use of state-of-the-art technology and higher quality controls, achieving films with:

• Better mechanical properties.
• Barrier properties.
• Chemical resistance.
• Degradable properties, as  oxo-degradable and bio-degradable films. that eliminate the cost of removal of the films and also disintegrate into compostable materials.

We recommend you consult with your local vendor of agricultural supplies regarding the premium products that leading manufacturers, with the newest technology, as the Armando Alvarez Group, can offer to achieve a better efficiency in your farming.

Here are some solutions available on the market:

• Solplast Black Mulch Film 
• Solplast Biosol
• Sotrafilm range
• Sotrafilm Black Biodegradable
• Reyenvas Mulch Films

Use of biodegradable films

Plasticulture obviously gives an opportunity for discussions in the field of eco-sustainable practices. It is a fact that most of the larger consumer markets have started to legislate specifically on good practices in agriculture and thus not only determine protocols of minimum thickness in the plastics used but also enforce plastic waste removal  from the fields and integrated recycling programmes.

For this reason, the current developments with biodegradable films, have  given an answer to ecological concerns from both the Industry as well as the Local Communities. The possibility of long term mulches (seasonal), elimination of costs of removal of plastic and avoiding plastic residue in the sub-soil are issues that can be solved today.

In this interdisciplinary study of three American universities, biodegradable mulches were less used than PE mulches, as expected, but there is great interest from respondents to learn a little more about this topic. While highlighting that their most important advantage is their friendly impact to the environment (52%) and the possibility of investing less in their removal (68%), there is a concern (55%) for the higher purchasing costs of this material.

The decision to adopt one type of mulch or the other will depend on many factors that, in this study, were expressed as the removal and disposal of mulching films, but there was greater concern about early breakdown in-season, a delayed breakdown postseason, in addition to the high cost of purchasing these materials.

Again, manufacturers that invest more in  mulch films production technology will play a key role, as they can make more specific formulations to successfully achieve biodegradability, along with improvements in mechanical properties to avoid, for example, the easy tearing of the material due to demanding mechanical applications on-field.

On this last point, we invite you to read our publications:

• eBook on the increased use of biodegradable mulches as a trend in the use of agricultural plastics
• Frequently asked questions on biodegradable mulches 

Advantages of linear low-density polyethylene mulching

Those who use plastic mulch made from LLDPE (linear low-density polyethylene),  should know that these are films very resistant to traction, tearing, and to the impact of low temperatures and stretching.

There are different options in the market focused mainly on providing different effects on the crop depending on the film’s control of solar light-radiation. For example, if the mulching is black/opaque, transparent/clear or bi-color; or if it is micro-perforated or perforated.

In the cultivation of blackberries, for example, one of the best mulches for planting is a black plastic, that provides an increase in the quality of the crop, reduces the environmental impact, and favours the precocity of what is sown. It is worth mentioning that making small perforations with plastic needles or using already micro-perforated films is suggested, as well as an efficient irrigation system applying the technique of drip irrigation through which moisture would be obtained under this plastic.

In strawberry crops, black plastic mulch reduces nitrogen loss during winter or the rainy season. You can also use transparent mulch to increase quickly the soil temperature for better crop precocity although the control of weeds is not so efficient.

Before placing these mulch films, it is advisable to prepare the soil as deep as possible to make the natural substrate as loose as possible. It is important that the soil fertilizer be applied before laying the plastic.

We invite you to read:

• Methods of agricultural soil treatment
• How to prepare the soil for harvesting

The radiation that is reflected, absorbed and transmitted by the plastic mulch determines, to a large extent, the positive and negative effect  on the temperature generated in the soil covered, which will have an impact on the development and yield of the crops. Therefore, a very thorough study must be performed regarding the material to be used and the type of soil on which it is going to work, to avoid mistakes that could produce negative results in the cultivation of berries or decrease the yield of the harvest in the best case.

In conclusion, the use of plastic mulches offers considerable improvements in the production and quality of what is planted. The essential aspect to consider  will be the selection of the most suitable plastic film for a specific crop and the results to achieve (earliness, size, color,..). Biodegradable plastic mulch  represents an option to consider, due to its excellent environmental advantages.