Microwave on wheels wins war on weeds
Posted
Researchers hope the adaptation of a humble household item could be a new weapon for battling weeds that cost Australia $4 billion each year.
Microwaves mounted on a trailer have proven to reduce weed emergence and improve grain yields.
The technology has been 11 years in the making for Melbourne University senior lecturer Graham Brodie.
"We are using microwave heating to cook plants and seeds that are in the soil, and that gives us an edge over some of the herbicide-resistant weeds emerging nowadays," Dr Brodie said.
His prototype is now on the verge of commercialisation and it is something he hopes could be a game changer for weed management.
Success in the field
The technology was trialled on about 25 different species of weeds, including broadleaf weeds and grass weeds in dryland crops.
More recently it was trialled in rice, with the pre-treatment of the soil to kill the weed seed banks and emerged weeds.
"We have had good success killing the plants quite quickly and also killing the seeds in the soil with a lot more energy," Dr Brodie said.
"In some field trials we have been able to reduce the weed emergence by about 85 per cent compared to no treatment at all, and we've also had probably about a 35 to 40 per cent increase in grain yield as a result of that."
Microwave power in the paddock
The microwave weeder prototype is a trailer system that features four independent microwave generators across the back of the trailer.
Each microwave generator has a 2 kilowatt power output — about twice as much as a household microwave.
Each has antennas that project the energy down onto the ground.
The radiation is restricted to within 2 centimetres of the antennas.
There are also two 7 kilowatt electrical generators on the trailer to produce the electricity required to drive the microwave power.
The trailer-mounted microwave weeder can be travel at 7–10 kilometres per hour.
Effects on soil health
Dr Brodie said microwave treatment did reduce bacteria populations on the top 5 centimetres of soil, but population recovery was fast.
"Within a month the populations were more than what we started with," he said.
"It releases nitrogen from the soil complex, which does mean you can get away with a little less fertiliser when we do treat the soil."
The treatment does affect some of the macro organic material such as worms and snails.
Dr Brodie said the cost to eradicate weeds that had emerged was about $80 to $120 per hectare, on par or slightly dearer than herbicide treatment.
"Treatment of the soil, like soil fumigation used in horticulture crops, would cost thousands of dollar per hectare, but that's what they pay anyway for their soil fumigation," he said.
Topics: weeds, agricultural-crops, dookie-3646
