Alberta's farmers are getting ready to plant their crops for another growing season, but some organic growers are more concerned about a new crop being sown south of the border this year.

The U.S. has just given the green light to plant genetically modified alfalfa. It's the first time a genetically modified perennial will be widely planted in North America.

Carstairs organic farmer Kris Vester is worried about the prospect of such alfalfa being planted in the U.S. this year.

Although it is not allowed in Canada, Vester says that doesn't mean it won't wind up in Canadian farmer's fields, blown across the border or carried by bees.

If that happens crops and animals on his land could no longer be certified organic, said Vester.

"You are going to end up with genetic contamination of your organic crop. And organic certification demands that you do not have any genetically modified genes in the genetic crop. So it could actually result in an organic farmer losing his organic status," he said.

"It may result in us having to stop using alfalfa and there is no other crop that could replace that."

Monsanto disputes GMO concerns

Alfalfa is grown as feed for livestock and some grain farmers use it to replace nitrogen in fields that have been left to fallow.

Vester also worries that not enough is known about the long term health effects of consuming genetically modified foods.

Concerns about genetically modified products are unfounded, said Trish Jordan, a spokesperson with Monsanto, the company that created the alfalfa seed.

"A lot of what you are hearing from the opponents just really isn't factual plain and simple. I don't know how else I can explain it," she said.

"You wouldn't be able to get anything approved if [it] had some sort of negative side-effect and that is obviously something that is looked at when these products are reviewed in the regulatory system."

Jordan points out that other genetically modified crops, like canola, are already widely grown in Canada. Monsanto's alfalfa has received regulatory approval in Canada, but is not currently being sold, she said.