The technology that could stop the use of plastic mulch

Australian research organization CSIRO has developed a sprayable biodegradable polymer membrane that can help farmers produce more while using less water, nutrients and agrochemicals.

The new technology called TranspiratiONal is an environmentally friendly alternative to agricultural plastics such as polyethylene, often also called plastic mulch. Tests have confirmed an increase in the water productivity of plants by more than 30 percent and at the same time supported weed control.

According to CSIRO, a global challenge is to grow more food with fewer resources. “The world’s population is growing, so food production will have to double by 2050 to feed an estimated nine billion people. The need to expand our food production also has an impact on the environment through the use of fertilizers and other chemicals, ”says CSIRO.

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Close-up of the spraying system with 3 sets of nozzles at a distance of one meter to improve the uniformity of the application (1 kg per square meter of treatment) - Photo: CSIRO

Close-up of the spraying system with 3 sets of nozzles at a distance of one meter to improve the uniformity of the application (1 kg per square meter of treatment) – Photo: CSIRO

Polymer membrane

The researcher Dr. Keith L. Bristow came up with the idea of ​​a polymer membrane. “I have studied a lot about soil health and how water interacts with the soil,” he says. “I was in China a while ago and was just horrified by the plastic mulch sheeting that was used there. We visited some fields where plastic was more dominant than the ground. This means that the soil pores were mostly clogged and toxins got into the soil and the surrounding water systems. “

My opinion was that all farmers should be able to apply the membrane, even those in Africa, with a simple hand sprayer

Dr. Bristow set out to develop a product that could replace plastic mulch films. He wanted to make a biodegradable product that could be sprayed. “My view was that all farmers should be able to apply the membrane, even in Africa with a simple hand sprayer or in the US with large mechanical machines,” he explains.

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Dr.  Keith Bristow:

Dr. Keith Bristow: “We want to make it as durable and inexpensive as possible.” – Photo: Keith Bristow

Field trials

After developing the membrane technology, CSIRO conducted several experiments and field trials in Australia. “We have used agricultural equipment large and small and have proven that our polymer membrane is accessible to smallholders in developing countries and highly mechanized large farmers and agribusinesses in developed countries,” says Dr. Bristow.

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Application of the membrane of a tomato field.  - Photo: CSIRO

Application of the membrane of a tomato field. – Photo: CSIRO

CSIRO demonstrated the sprayable technology in irrigated field trials in Australia with melons, tomatoes, sorghum and cotton. The tests confirmed an increase in the water productivity of the plants by more than 30 percent and at the same time contributed to the control of weeds.

“We have our proof of concept, but we still need to refine the polymer spray,” says Dr. Bristow. “We want to make it as durable and inexpensive as possible. At the moment the costs are probably higher than those of the widely used plastic mulch film. “

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Installation of the pre-formed plastic mulch film treatment.  - Photo: CSIRO

Installation of the pre-formed plastic mulch film treatment. – Photo: CSIRO

Release of toxins

Farmers have Dr. Bristow and his team communicated that if they could use an inexpensive sprayable, biodegradable polymer membrane, they would stop using plastic mulch film. “By using a sprayable, biodegradable membrane, you don’t have to pull back any deteriorating plastic mulch film during or after harvest,” says Dr. Bristow. “And a lot of the plastic mulch films still cause problems. It burns what the government and the community doesn’t like, or it ends up in a landfill. And when it breaks down into smaller fragments, it releases toxins into the soil and our water systems, including streams, rivers, and groundwater.

The farmers in the trials were generally satisfied with the ability of the polymer membrane to cover the soil. Weeds were controlled and water saved, which led to more production. “Our goal is to maximize transpiration and minimize soil evaporation,” emphasizes Dr. Bristow.

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A field of tomatoes that have been sprayed with a polymer treatment.  - Photo: CSIRO

A field of tomatoes that have been sprayed with a polymer treatment. – Photo: CSIRO

Biodegradable

The field trials have shown a number of advantages of CSIRO’s polymer membrane over the plastic mulch films currently used by farmers. The polymer membrane is biodegradable and most plastic mulch films are not. This new product is sprayable. Farmers can use existing agricultural equipment for the application – with minor, inexpensive modifications. The application of plastic mulch films is expensive because special agricultural equipment is required.

Plastic mulch films can cause extreme surface temperatures. However, the use of the polymer membrane moderates the soil surface temperatures. The tests showed that plastic mulch films caused damage to seedlings and the death of plants. The use of the polymer membrane caused minimal to no damage to seedlings.

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Applying the highest polymer treatment (1.5 kg per square meter).  - Photo: CSIRO

Applying the highest polymer treatment (1.5 kg per square meter). – Photo: CSIRO

Safe use of the polymer membrane

Dr. Bristow and his team made sure that the polymer membrane is safe to use. “We took soil samples with the polymer and from the products, for example the skin of melons,” he says. “We probably did a few hundred different tests. The results proved that the product did not contain anything unpleasant or toxic and that it is biodegradable. Farmers can simply go to the field after the harvest. “

Dr. Bristow would prefer to do some pre-commercial farm trials to refine the polymer formulation, its application and its effects. He is currently in discussions with investors to finalize the preparations for the pre-commercial studies. The farmers are very interested. “I am contacted by farmers every week, sometimes six times a week. People from all over the world call me. “

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Harvested tomatoes filling the harvest container.  - Photo: CSIRO

Harvested tomatoes filling the harvest container. – Photo: CSIRO

Free more than 1,000 gigalitres of water

CSIRO states that achieving the original goal of using 10 percent less water without losing yield in Australian irrigated agriculture would release more than 1,000 gigaliters of water. “This could be used to grow additional crops and / or improve the environmental flows in our waterways,” says CSIRO.

“There are real headaches with plastic mulch films”

Farmer Dan Harris of Myrtle Park Produce in Finley, New South Wales, participated in field trials of the sprayable biodegradable polymer membrane. “If that were available, I would definitely use it,” he says.
Harris says spraying the polymer membrane on the floor was a simple process. “We put the polymer in a tank behind a tractor and applied the polymer to the ground with nozzles”
The New South Wales farmer enjoyed being involved in the experiments. “There was a little manufacturing problem at the beginning, but when that was fixed it was fine. In the first year we tried different amounts of polymer per square meter. That made it clear how thick we needed. I thought it showed a lot of potential at the higher rate of 1kg per square meter. “
In the second field trial, Mr. Harris raised a crop of melons using the polymer membrane. “It has increased the water productivity of the plants and suppressed weeds. And I was able to leave the polymer on the floor and it just collapsed. “I really wanted to pursue it, but unfortunately the funding dried up.”
Mr Harris says he would use the new technology in place of plastic mulch film when it became available. “It’s the flexibility; and not having to deal with plastic. We lay plastic, but then have to retrieve and dispose of it, which is a real headache. And it’s expensive. If we could just spray the membrane I’d love to pay double what the plastic wrap mulch cost. Even if of course the cheaper the better … “
He points out that the use of plastic mulch film is also at the expense of the public purse. “It’s not good for the environment and not a good long-term solution for our industry. Hopefully they can lift the polymer membrane off the ground. It’s a great innovation. A few farmers will shy away from it at first, but if you show them how flexible and easy it is, they’ll come by. “

Farmer Dan Harris of Myrtle Park Produce in Finley, New South Wales, participated in field trials of the sprayable biodegradable polymer membrane.

Farmer Dan Harris of Myrtle Park Produce in Finley, New South Wales, participated in field trials of the sprayable biodegradable polymer membrane. “If that were available, I would definitely use it,” he says. – Photo: Dan Harris

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