GM
Crop Farm Scale Evaluations:
Scientific Steering Committee Advice
FARM-SCALE EVALUATIONS OF GM CROPS: SITE SPLITTING AT LOW BURNHAM
Introduction
At an Adjournment Debate in the House of Commons about the Farm Scale Evaluation (FSE) research on 1 May 2001, Ian Cawsey MP (Brigg and Goole) questioned the scientific validity of the way that the FSE site at Low Burnham had been split to provide the two experimental halves. Mr Causey's concern was that as strip farming is traditional in the area (allowing areas of cropping that are narrower than modern arable fields), there is no guarantee that what are now two halves of the same field will have been farmed in the same way over the years. They may have been farmed in different strips with different crops and pesticide regimes, and therefore it is likely that the two halves of the field would produce completely different results.
Advice from the Scientific Steering Committee
Officials in DETR have consulted the Scientific Steering Committee and their advice is set out below.
The farm-scale evaluations are addressing the hypothesis that there is no difference in the impact on the abundance and diversity of farmland wildlife between the type of herbicide regime used with the genetically modified herbicide tolerant crops and conventional herbicide regimes used on equivalent non-GM crops. The study design requires data from a total of 60-75 sites of each crop over the three-year period of the programme. The fields are split and then one half is chosen at random for sowing with the GM crop and the non-GM crop is sown in the other half. This means that each site has its own built-in control. The criteria for splitting the sites to provide the built-in control are designed to ensure that the two halves are as similar as possible in terms of soil type, boundary features, previous management and other variables. Such careful splitting is essential to ensure that the differences (if any) in biodiversity observed by the scientists between the two halves of the sites are the result of different herbicide regimes, rather than other uncontrolled factors.
Even though a system of strip cultivation has been traditional in the area around Low Burnham, the site where the FSE crop is situated has been farmed as a discrete field for the last three years, with a single crop and associated management at any one time. Historically the field contained five strips, four of these have been farmed as one for six years and the last strip was added three years ago. Last autumn (2000) the field was sown with winter oilseed rape, but the crop subsequently failed to establish properly in the wet weather. While half the field was badly damaged by slugs, the other half fared only slightly better and was subsequently sprayed off by the farmer.
In making their decision to split the site at Low Burnham, the FSE scientists placed their division so that it was perpendicular to the historical positioning of the five strips that were present in the field before three years ago and the failed oilseed rape crop sown last autumn. This ensured that the split allowed each of the FSE experimental halves to include similar areas of previous strip cultivation, slug damaged and sprayed-off crop.
The Scientific Steering Committee has reviewed the history and splitting of the site at Low Burnham. It advises that as:
- the site has been cultivated with a single crop within each growing season for the last three years,
- the scientists have split the site to account for strip cultivation in the past, and
- the scientists have split the site to account for management differences last season,
it is confident that the careful splitting of the site carried out by the FSE scientists accounts for all previous cropping and within field variation. The Scientific Steering Committee advises that research at the site will provide reliable information about the effects on biodiversity of the herbicide treatments being studied in the FSE.
Secretariat to the Scientific Steering Committee, DETR
02 May 2001
Page published 10 October
2001;
Page last modified
10 August, 2002