Livestock farming systems and sustainable drinking water production: proposition of risk indicators at different organisational levels

In the north-east of France, livestock farms, mainly dairy cattle farms, in creasingly attempt to replace grass fodder by silage maize. This evolution of agricultural practices modifies the quality of groundwater for human con sumption. We propose three indicators of diffuse nitrate pollution risk at three organisational levels: (i) the livestock unit: a 'hydro-appraisal' ba sed on cattle feeding management is calculated for the dairy and the fatten ing units of the Experimental Research Station of Mirecourt, in order to co mpare the pollution risks due to the production schemes (dairy cows fed wit h grass against maize, beef steers fed with grass against beef calves fed w ith maize); (ii) the livestock farm: an indicator based on the cropping pla n and on the mean nitrate leaching under the main cropping and grassland sy stems is calculated on twelve livestock farm types classified from 2211 far ms in Lorraine, in order to identify the fanning systems that present a pol lution risk; (iii) the livestock farming region: the previous indicator is located at the French commune scale by taking into account the proportion o f farm types and the relative farming area used by each type, in order to d ifferentiate geographic areas according to the estimated pollution risk. Th e construction and the combining of such indicators contribute to the devel opment of decision support tools for those concerned with water resource pr otection and sustainable agricultural land use in livestock farming regions . (C) 1999 Elsevier Science B.V. All rights reserved.