Unsprayed field margins: effects on environment, biodiversity and agricultural practice

A management strategy developed for field margins to reduce pesticide drift to non-target areas and to promote biodiversity on arable land was investigated. It involved not spraying herbicides and pesticides in a strip 3 or 6 m wide on the edges of winter wheat, sugar beet and potato crops. This strategy was compared with spraying the edges. The effects on pesticide drift, arable flora, invertebrates, vertebrates, costs and acceptance by the farmer were studied. This article reviews the most important results. Interviews with farmers showed that field margins were sprayed intensively. Drift measurements demonstrated that creating unsprayed buffer zones of 3 m width is a very effective way of reducing pesticide drift to the ditches demarcating the field (drift is reduced by about 95%) and risks to aquatic organisms. The presence and abundance of plants associated with arable farming increased substantially in the unsprayed edges, as did the floristic value of the vegetation. The impact on epigeic soil invertebrates was relatively minor. However, there was a pronounced effect on phytophage insects. The number of visits to the unsprayed edges by Motacilla flava flava, an insectivorous bird, also increased. A cost-benefit analysis based on the yield losses showed that it is very feasible to incorporate unsprayed crop edges in the cultivation of winter wheat and potatoes. In sugar beet, however, the cost is too high, However, for reasons to do with agronomy, farming equipment and socio-psychology, farmers will accept unsprayed cereal edges or grass strips but not unsprayed potato edges. From their perspective the most important aspect for acceptance in farming practice is a flexible width of the unsprayed crop edges. (C) 1999 Elsevier Science B.V. All rights reserved.