Agricultural practices and water quality in a small intensive breeding area : a pilot experiment carried out within the framework of the "Rade de Brest" contract

Abstract

A 3-year multidisciplinary research programme, supported by the EU as part of its "Life " pilot experimental scheme, has enabled the scientific bases of the Brest Harbour contract to be established. The agricultural aspects of this programme were undertaken jointly by Cemagref Rennes and the INRA. Investigations concentrated on a 6 sq. km watershed known as the Kerouallon Basin. This watershed, which is given over to very intensive livestock farming, is situated in a Manure Surplus Area. Farming practice across 250 parcels was closely observed over a two-year period years. The presence of nitrogen, phosphorous, pesticide and heavy metal in agricultural products, the ground and the water were analysed. This enabled us to establish a diagnosis of agricultural pollution at parcel, farm and basin levels. Proposals were then made to the farmers concerning economically-viable alterations to their farming practice to take into account environmental problems. A bottom-up approach was adopted - firstly, reduction of inefficient techniques currently used by the farmers, secondly, introduction of modern practice regarding animal feeds, effluent management, crop rotation rationalization and lower-risk rotations, finally, land development for depolluting the residual waste flow.