MODELING DETERMINANTS OF NITROGEN LEVELS IN DANISH WATERCOURSES, LAKES, COASTAL AND MARINE WATERS, 1989-2004

摘要

This study provides an analysis of the determinants of nitrogen levels in Danish surface waters, and examines the impact of Danish agricultural management policies on these nitrogen levels. The study has four main findings. First, the Danish Government has used a variety of measures to reduce nitrogen balance in agriculture, including reduced use of natural and man made fertilizers to meet the targeted reduction in agriculture nitrogen loadings of 127,000 tonnes N per year. Second, nitrogen balances have fallen from 142 kg/ha in 1989-1992, to 122 kg/ha in 1993-1996, to 105 kg/ha in 1997-2000 and to 92 kg/ha in 2001-2004. Third, nitrogen concentration levels in watercourses have fallen from 8.78 mg/l in 1989-1992, to 7.15 mg/1 in 1993-1996, to 6.70 mg/1 in 1997-2000 and to 5.70 mg/1 in 2001-2004 and in lakes have fallen from 1.88 mg/1 in 1989-1992, to 1.87 mg/1 in 1993-1996, to 1.45 mg/1 in 1997-2000 and to 1.50 mg/1 in 2001-2004. Fourth, agriculture net nitrogen balances in watercourses, lakes, coastal waters and fjords and marine waters are significantly driven by nitrogen loadings in agricultural soil and by precipitation runoff.