The soil content of mineral nitrogen to 1 m depth has been measured several times in the leaching period on 600 conventional agricultural fields in a SQUARE GRID with a side length of 7 km. The measurements were also carried out in 26 ecological fields. Information on management practice was collected every year and soil physical parameters were determined. The soil content of mineral nitrogen in autumn was compared. Furthermore the nitrate leaching values were calculated in most of the conventional fields and in nine of the ecological fields by means of the DAISY nitrogen model.