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The technology that could stop the use of plastic mulch

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

The new technology, named TranspiratiONalis an environmentally friendly alternative to agricultural plastics such as polyethylene, which are often referred to as plastic mulch. Tests have confirmed an increase in plant water productivity of more than 30 percent and at the same time contributed to weed control.

According to CSIRO Growing more food with fewer resources is a global challenge. “The world population is growing and food production will have to double by 2050 to feed an estimated nine billion people. The need to increase 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 one meter apart 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 one meter apart 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’ve worked a lot on soil health and the interaction of water with the soil,” he says. “I was in China a while ago and was just horrified by the plastic mulch sheeting they used. We visited some fields where plastic was more dominant than the ground. This means that the soil pores were mostly clogged and toxins were entering the soil and surrounding water systems. “

In my opinion, all farmers should be able to apply the membrane, including those in Africa who use a simple handheld 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. “In my opinion, all farmers should be able to apply the membrane, including those in Africa who use a simple hand sprayer or those in the US who use large mechanical machines,” he explains.

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Dr.  Keith Bristow: "We want to make it as durable and inexpensive as possible." - Photo by Keith Bristow

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

Field trials

After developing the membrane technology, CSIRO conducted several experiments and field trials in Australia. “We have used large and small agricultural implements and have proven that our polymer membrane is accessible to smallholders in developing countries and to 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 plant water productivity of more than 30 percent and at the same time helped with weed control.

“We have our proof of concept, but we have to refine the polymer spray further,” says Dr. Bristow. “We want to make it as durable and inexpensive as possible. Right now, the cost is likely to be higher than 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 said they would stop using mulch film if they could use an inexpensive sprayable, biodegradable polymer membrane. “By using a sprayable, biodegradable membrane, you don’t have to pull up a deteriorating plastic mulch film during and after harvest,” says Dr. Bristow. “And a lot of the plastic mulch film is still causing problems. It burns what the government and community doesn’t like, or goes to a waste disposal facility. And when it breaks down into smaller fragments, it releases toxins into the soil and into our water systems, including streams, rivers and groundwater below. “

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, resulting in 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 farm 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 application 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 the 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

Polymer membrane safe to use

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

Dr. Bristow would prefer to conduct some pre-commercial agricultural trials to optimize the polymer formulation, its application and performance. He is currently speaking to investors to complete the final stage of highlighting. “We are doing pre-commercial trials. There is enough interest from farmers. “I am contacted by farmers every week, sometimes six times a week. People call me from all over the world. “

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Harvested tomatoes fill the harvest container.  - Photo: CSIRO

Harvested tomatoes fill the harvest container. – Photo: CSIRO

Release more than 1,000 gigaliters of water

CSIRO states that reaching 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 when using plastic mulch film”

Farmer Dan Harris of Myrtle Park Produce in Finley, New South Wales, participated in field trials of the sprayable biodegradable polymer membrane. “If this were available, I would definitely use it,” he says.
According to Harris, spraying the polymer membrane on the floor was a straightforward process. “We put the polymer in a tank behind a tractor and applied the polymer to the ground with nozzles.”
The farmer from New South Wales was happy to take part in the experiments. “In the beginning there was a little manufacturing problem, but once that was ironed out it was fine. In the first year we tried different rates of polymer per square meter. That made it clear how thick we needed. I thought it shows a lot of potential at the higher rate of 1kg per square meter. “
In the second field trial, Mr. Harris raised a melon crop using the polymer membrane. “It has increased the productivity of the harvest water and suppressed weeds. And I could leave the polymer on the floor and it just collapsed. “I really wanted to pursue it, but unfortunately the funding has dried up. “
Mr Harris says he would use the new technology in place of plastic mulch sheeting when it became available. “It’s the flexibility; and don’t have to deal with plastic. We put plastic, but then have to get it back and dispose of it, which is a real headache. And it’s expensive. If we could just spray the membrane I’d like to pay twice as much as the mulch for plastic sheeting. Although the cheaper the better, of course … “
He points out that the use of plastic mulch film also comes with a public cost. “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. Some farmers will shy away from it at first, but if you show them how flexible and easy it is, they will come around. “

Farmer Dan Harris of Myrtle Park Produce in Finley, New South Wales, participated in field trials of the sprayable biodegradable polymer membrane. "If this were available I would be using it for sure", he says.  - Photo: Dan Harris

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