Open-slather planting of genetically modified (GM) crops would net Australia $8.5 billionduring the next decade, government researchers estimate.

According to a report by the Australian Bureau of Agricultural and Resource Economics
(ABARE), GM crops would boost yields, cut costs, help the environment and boostbiodiversity.

But the Australian Greens have rejected the $8.5 billion figure and warned that introducing
the controversial crops would do more harm than good.

Most GM crops are banned in Australia but farmers can plant GM cotton and NSW and Victoria
have allowed GM canola from this year. State governments decide what can be sown.

According to the Economic Impacts of GM Crops in Australia report, if all GM crops were
allowed now, the Australian economy would benefit by $8.5 billion by 2018.

NSW would benefit the most, by $3.5 billion, followed by Western Australia on $2.4 billion.

Delaying the introduction of GM canola by five years would lead to "foregone benefits" of
$97 million in WA and $66 million in South Australia, the report said.

ABARE's executive director Phillip Glyde said the report showed that maintaining the bans on
GM crops would cost farmers dearly.

"Delaying GM uptake means we are foregoing significant economic benefits for regional
Australia," he said.

GM crops were more resistant to pests and weeds, meaning fewer chemicals had to be used,
which increased yields. Labour, machinery and fuel costs also fell with GM crops, the report said.

"Managing GM crop production is generally easier and less time-consuming than non-GM crop
production," the report says.

GM canola and soy beans had strong potential for Australia and wheat and rice could work
down the track, it said, although maize was of uncertain economic benefit.

The report found GM crops were good news for the environment because there was less crop
spraying, which meant cleaner soil and water and more beneficial insect species.

But Greens senator Rachel Siewert said ABARE had been pro-GM "from the start" and the report
lacked credibility.

"It's grossly exaggerated, I question their figures, I question their objectiveness,"

Senator Siewert said.

"It's a very biased view."

She said ABARE used figures provided by industry without independently analysing them.

She said the report had downplayed the costs and potential problems associated with using GM
crops. For example, growing them could exclude Australia from some lucrative markets in
Europe and Japan.

Senator Siewert said GM crops were unproven and there were health concerns about introducing
them into the food chain.

The Greens were also worried about the crops contaminating non-GM areas. And they may need
more chemicals in the long-term than other crops, she warned.

"I think there needs to be a lot more independent research done on the costs and benefits,"

Senator Siewert said.

The ABARE report was funded by the federal Department of Agriculture, Fisheries and Forestry