This dataset consists of farm management data which includes crop drilling dates and herbicide application dates. The data relate to arable fields in which a range of ecological measurements were collected, including species counts in the following areas: weed seedbank, vegetation in the crop, field edge vegetation, invertebrates. Each field was sown with a combination of genetically modified and conventional crops, either Beet, Maize, Spring-sown Oilseed Rape or Winter-sown oilseed Rape. The data were collected as part of the Farm Scale Evaluations (FSEs), a four-year programme of research by independent researchers aimed at studying the effect that the management practices associated with Genetically Modified Herbicide Tolerant (GMHT) crops might have on farmland wildlife, when compared with weed control used with non-GM crops. Data were collected by a consortium of: the Institute of Terrestrial Ecology, ITE (now the Centre for Ecology & Hydrology, CEH), the Institute of Arable Crop Research (now Rothamstead Research, IACR) and the Scottish Crop Research Institute, SCRI (now the James Hutton Institute, JHI). Data were collected for four crops overall (Beet, Maize, Spring-sown Oilseed Rape and Winter-sown oilseed Rape).