Microwave: A new tool in herbicide resistance

Microwaving weeds to deal with herbicide resistance in no-till farming


University of Melbourne senior lecturer Graham Brodie with the simple but effective set up used to demonstrate the work of microwave energy.

University of Melbourne senior lecturer Graham Brodie with the simple but effective set up used to demonstrate the work of microwave energy.

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A 10-year project focusing on the use of microwaves to zap weeds in no-till cropping systems is almost ready for commercialisation.

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A 10-YEAR project focusing on the use of microwaves to zap weeds in no-till cropping systems is almost ready for commercialisation.

University of Melbourne senior lecturer Graham Brodie has gone back to his roots as an electronic engineer to apply microwave energy to weeds and soil to eliminate weeds while improving soil health.

Dr Brodie was among the speakers at the recent Monsanto Cotton Grower of the Year field day, hosted by the 2016 award winners Ian, Marilyn and Harry Carter at Connamara, Quirindi.

He used a basic model – a standard household microwave, similar to the first prototype – to demonstrate the work of microwave energy.

The team has been working on different prototypes over the past 10 years and has created a trailer using four microwave generators to apply the energy to weeds and soil.

“They’re two-kilowatt microwave generators, about twice the output of a household microwave, and the idea is that each one can be turned on and off independently,” Dr Brodie said.

“The machine is set up to go in rows between crops and the configuration can be changed very easily. It can travel over the canopy, but still deliver the microwave energy down to ground level using a series of tubes.”

Zapping weeds could be the answer to growing herbicide resistance issues in no-till farming, Dr Brodie said.

“The longer we go down this path of zero till, the more issues we're going to have with herbicide resistance, and because this doesn't have contact with the ground, it's compatible with zero till farming.”

The main focus has been for dryland grain crops, with the machine already trialled on about 25 different broadleaf and grass weeds.

Trials have shown promise in not only knocking down weeds, but increasing yields through improved soil health.

ELIMINATING weeds isn’t the only benefit from microwave energy, with trials showing an improvement in soil health.

It’s a costly process, but applying more energy can treat the soil to kill weed seeds.

“It’s a bit like soil fumigation which is used in high value horticulture, so we’ve had a lot of interest for work in glasshouses and greenhouses,” Graham Brodie said.

Dr Brodie said the soil treatment trials resulted in a 30 per cent increase in yields.

“That’s due to a combination of far less competition from weeds themselves and the release of nutrients from the soil for the plants.”

While soil microbial activity takes a hit at first, it improves in the months following treatment.

“It does reduce populations of microbes in the top few centimetres of the soil immediately after treatment, but the populations regenerate quite quickly in the next few weeks, so we get a flush of microbial activity in the soil,” Dr Brodie said.

The next step is to secure funding to create a detailed design and build a prototype before loaning it out to growers for field evaluations.

“What I envisage for the first field version is a machine that can run off the PTO (power take off) of a tractor.”

PhD student Muhammad Jamal Khan with the microwave trailer.

PhD student Muhammad Jamal Khan with the microwave trailer.

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