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GM Crop Farm Scale Evaluations:
Scientific Steering Committee Advice

FARM-SCALE EVALUATIONS OF GM CROPS

ANSWERS TO QUESTIONS RAISED BY WEST LINDSEY DISRICT COUNCIL

Introduction

In a letter and briefing note (5 June 2001) (see attached) to Mr Meacher following a meeting with the Minister on 10 May 2001, West Lindsey District Council raised a number of issues about the design of the Farm Scale Evaluations (FSE). This letter included two issues that required the advice of the Scientific Steering Committee overseeing the FSE.

  1. The first issue took the form of a briefing note to the Minister and questioned whether the design of the experiment was sufficient to account for effects of potential soil differences existing within sites, and to take account of any effects of experimental GM crop management on soil ecology.
  2. The second issue took the form of a question addressing the issue of the relatively high concentration of FSE sites in Lincolnshire.

Advice from the Scientific Steering Committee

Officials in Defra have consulted the Scientific Steering Committee and their advice is set out below.

1. The design of the experiment and soil related issues

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 criteria for the selection of sites laid down by the Scientific Steering Committee require that the farms participating in the study represent a range of both high intensity and low intensity farming practices and are representative of the farming areas where the particular crops are grown. Such coverage is essential to ensure that the full range of habitats and wildlife likely to be exposed to the new herbicide regime is investigated and thus that the findings have countrywide relevance. 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 provide the built-in control by ensuring 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. This is further ensured by the fact that the sowing of the GM and non-GM crop between the two halves of each site takes place at random. The number and distribution of sampling areas within the experimental fields makes sure that each part of the experimental site is thoroughly surveyed and potential differences in soil type (or other related factors) within the sites are taken into account.

This design allows the effects of the herbicides on wildlife in the two halves to be assessed more accurately than by comparison with wildlife in the crop before the start of the experiment. The wildlife present in crops is affected by factors such as structure of vegetation and crop type. Wildlife present in the bare field before sowing or in a previous, different crop the year before will not be the same as that present in the experimental crop. Measurements of differences in wildlife between a pre-trial audit and within the experimental crop during the experiment would not allow the effects of the herbicide regimes to be measured. However, soil samples are taken from each side of each experimental site before the crops are drilled or herbicides are applied to provide baseline information on the density of weed seeds present in the soil seed bank.

The Advisory Committee on Releases to the Environment (ACRE) has already assessed the potential effects on soil ecology of the GM crops themselves, and assessed them as safe to human health and the environment. The Advisory Committee on Pesticides (ACP) has already assessed the potential effects on soil ecology of the herbicides used in the experiment before granting experimental approval. The experiment is also investigating the effects of the herbicide management on earthworm activity (through counts of worm casts).

2. The distribution of FSE sites in Eastern England

Winter and spring oilseed rape is grown in England and Scotland with a little in Wales mainly in the border region. The distribution in each geographical region in recent years is shown in the table below. This indicates that to mirror this national distribution pattern in the FSE up to 25 winter oilseed rape sites and 14 spring rape sites would be expected in Eastern England, including Lincolnshire. In addition, beet and maize crops are grown in Lincolnshire and this is similarly reflected in the distribution of beet and maize sites in the FSE. Although the Scientific Steering Committee is satisfied that the selection of FSE sites chosen to date has aimed to represent commercial crop production, it will ensure that areas do not become over-represented during the course of the programme.

 

WINTER RAPE

SPRING RAPE

Region

% grown in region

% grown in region

Scotland

9

13.3

Northern England

18

17.8

Midlands England

15

26.7

Eastern England

33

18.5

South east England

16

15.5

South west England

8

7.3

Wales

1

0.6

Secretariat to the Scientific Steering Committee, Defra
20 July 2001

Page published 10 October 2001;
Page last modified 10 August, 2002

Department for Environment, Food and Rural Affairs