GM Crop Farm-Scale Evaluations: Fact Sheets
The Farm Scale Evaluations of Genetically Modified Herbicide Tolerant Crops
An outline of the research, its rationale, organisation and scope by the independent Scientific Steering Committee overseeing the project, February 2001
Introduction
The Farm Scale Evaluations (FSE) of Genetically Modified Herbicide Tolerant (GMHT) crops are among the largest ecological experiments of their type ever carried out on agricultural land and will provide much-needed information about the effects of both conventional and GMHT herbicide management systems on farmland biodiversity. However, the research is also possibly the most controversial and misunderstood farmland ecology research ever undertaken. This brief paper is prepared by the independent Scientific Steering Committee (SSC) overseeing the research in order to outline the rationale, organisation and scope of the evaluations and to address some of the misconceptions about the project.
Rationale
Since 1998, the European Union has encouraged national regulatory agencies to consider the potential long-term environmental effects of agricultural systems involving GM crops. This is in addition to the existing regulatory framework that is designed to determine the direct environmental impact and the effects on human or animal health of novel GM crop varieties.
Herbicide-tolerant crop varieties are among the 'first generation' of GM crops, although similar traits can also be introduced by conventional plant breeding. Cultivation of these varieties involves application of a broad-spectrum (i.e. non-selective) herbicide that will kill most plants except those crops expressing the herbicide tolerance. By contrast, conventional intensive production could involve more frequent spraying with one or more specific herbicides in order to achieve the same level of weed control.
There is widespread agreement that the marked decline of farmland wildlife in recent years is largely attributable to the increased efficiency of modern farming. In particular, the use of herbicides, fungicides and insecticides, together with new crop cultivation methods, effective management of fertiliser application and irrigation, ensures that most of the productive capacity of the land supports crop production at the expense of wild species, including weeds. These weeds and their seeds do, however, form the base of the food chains that support much farmland wildlife, including many insects, birds and mammals. The FSE have been set up to determine the ways that the novel patterns of herbicide use permitted by the cultivation of herbicide-tolerant crops will affect the abundance of weeds, their seeds and of various indicator species of invertebrates.
Five types of herbicide-tolerant crop are being studied: spring-sown and winter-sown oilseed rape, forage maize and beet (sugar and fodder varieties). There is currently an agreement with seed companies that none of these varieties will be advanced towards general cultivation until the results have been peer reviewed and published, and decisions made by the competent authorities.
Organisation
As there is natural variability in soil type, prevailing weather conditions, farmland biodiversity and management intensity, considerable replication is needed in the Farm Scale Evaluations to ensure the experiment represents the areas where these types of crops could be grown. The aim is to have 60-75 fields of each crop measured over the planned three-year duration of the experiment. The sites are selected to be representative of the range of farming intensities found within the UK for each particular crop type. Each field is sown half with the herbicide tolerant variety and half with a non-GM variety of the same crop type, and each half-field is managed appropriately. Herbicide application in the GMHT crops is managed according to the recommendations developed by the manufacturers and application on non-GM halves is within typical practice for that crop on a particular farm.
Measurements of abundance of those key species of wildlife that can be measured with confidence are made throughout the growing season in the crop and in the field margins of both halves of each site. Measurements are also made of weed and weed seed abundance in the year following harvest. Although the evaluations do not directly measure management effects on all types of biodiversity, they are investigating those that are likely to be most sensitive to the changes that the introduction of GM herbicide tolerant crops will bring. Effects on organisms such as weed seeds and insects that are at the base of farmland food chains will be used to model the potential effects of GMHT management on organisms such as birds that are further up the food chain. In addition, some direct research is being undertaken on the effects of GMHT management on farmland birds.
Calculations suggest that an experiment of this size would detect, at worst, a 33% decrease in biodiversity between the treatments; for many taxonomic groups much smaller differences will be detectable. Currently one year's worth of observations has been made on spring-sown crops with work on winter oil-seed rape now underway. The Government funds the FSE research programme. The agricultural industry body SCIMAC (the Supply Chain Initiative in Modified Agricultural Crops) liases with farmers to select appropriate experimental sites. The research is undertaken under contract by an independent consortium of Research Institutes (The Centre for Ecology and Hydrology, The Scottish Crops Research Institute and the Institute for Arable Crop Research). The overall programme is overseen by the independent SSC. The SSC also advises ministers on the conduct of the evaluations and its outputs are available on the DETR web site: www.defra.gov.uk/environment/fse/index.htm.
Scope
The FSE are intended to address the basic issues outlined above, i.e. whether cultivation systems involving herbicide-tolerant crops have a significant effect (positive or negative) on biodiversity. The FSE do not replace existing elements of the regulatory system designed to assess the direct impacts of the crops themselves; instead they augment them by extending the experiments to cover the entire production system. The FSE are not, therefore, investigating the possible effects of GM crops on human or animal health, public confidence in genetically modified agricultural produce or the economic justification for such crops. They are also not concerned with the exact nature or derivation of the herbicide tolerance. Other regulatory bodies such as ACRE (The Advisory Committee on Releases to the Environment) considers such issues. The research is only investigating those crops tolerant to glyphosate or glufosinate ammonium herbicides. The FSE are not investigating other GM herbicide tolerant crops (such as those that are tolerant to several herbicides) nor other GM traits (such as insect-resistance) that may become available to farmers in the UK. The FSE are also relatively short-term (three years) with, in most cases, only a single GM crop grown in a field in a single year. However, they will inform the debate about assessing possible longer-term effects, such as the potential changes to agricultural rotations and the impact this could have on wildlife, and will provide a benchmark for other studies that might be deemed necessary.
Page published 5 April
2001;
Page last modified
10 August, 2002