Influence of ecological measures on nitrate content of groundwater

In a project of the evaluation of ecological measures in Swiss agriculture, the goal of an average reduction of nitrate content in groundwater by 5 mg NO3/l between the period of 1990 to 1992 and 2005 is examined in four regions of the canton of Berne. Up to 2001, the nitrate content of 214 water catchments with farmland in the drainage basin decreased by 1.8 to 18 mg NO3/l. In comparison with this, the nitrate content of 49 water catchments with wooded and unproductive areas in the drainage basin decreased only by 0.3 to 7 mg NO3/l. In the Bernese Central Plain and in the Prealps, there was a significant decrease of nitrate content in catchments with farmland in the drainage basins, yet not in the Jura and in the Alps. In the assumption of a constant trend in the next years, the reduction goal will only be achieved in the Prealps.