GM trials: In depth

Oilseed rape has been tested at UK trial sites

The announcement that Wales will have three trial sites for genetically-modified crops has taken the Welsh Assembly and environmentalists by surprise.

BBC Wales's environment correspondent Roger Pinney looks at the complicated background of seed trials, licensing and legal challenges against genetically-modified organisms (GMOs).

The crop which is to be tried in Wales is a fodder maize called Chardon LL and has been produced by a company called Aventis.

The seed has been genetically-modified to be resistant to the herbicide Liberty Link.

It is licensed for use within the European Union - but it has not yet been added to the UK seed list.

John Cottle was Wales's first GM farmer

That process has been held up following a long and complex set of legal challenges from Friends of the Earth and other organisations, in which it emerged there were apparent flaws in the French tests on which the EU licensing was based.

There has been a common misconception that the Farm Scale Trials have been set up to test the effect of genetically-modified organisms on the environment.

That has already been done say scientists in favour of GMO, but not satisfactorily according to opponents of the tests.

The trials are supposed to test the farming system and involve the trial crop's effect on biodiversity.

They are overseen by a group called the Scientific Steering Committee (SSC) Its chaired by Professor Chris Pollock.

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The process of approving trial sites begins with seed companies and other interested groups (including the National Farmers' Union), who are members of a consortium called SCIMAC.

SCIMAC works with farmers to draw up a list of potential trial sites and that list is supplied to contract scientists, who undertake the trials.

The contractors whittle SCIMAC's list down and supply it to the SSC.

In turn, the SSC checks the list on behalf of government:

Ensure there are enough sites to make it scientifically valid.

Ensure that there is sufficient geographic spread to represent the climate and soil types for regions where the crop is likely to be grown.

The SSC - which takes no account of politics or political boundaries - then gives the list to Department of the Environment, Transport and Regions (DETR), which releases it.

Once the crop trial is over, the crop is ploughed into the ground and does not get fed to animals.