Effect of vegetation type and growth stage on dewfall, determined with high precision weighing lysimeters at a site in northern Germany

The amount and temporal distribution of dewfall on grass, maize and winter barley was measured with four high precision weighing lysimeters at a site in northern Germany during 2004–2005 to quantify the contribution of dewfall to the water balance of the region and to assess how dewfall is affected by the vegetation cover. Two lysimeters were under continuous grass, two were cropped (maize from April through September 2004, followed by winter barley until July 2005, fallow the rest of the time). Observed dewfall ranged from 27.1 to 31.8 mm per year, which was 5.5–6.9% of the annual rainfall. In several months of the study period dewfall was >20% of the monthly precipitation. On fallow lysimeters there were fewer nights with dewfall and less dewfall per event than on lysimeters with grass. After crops were planted the number of dewfall-nights and the amount of dewfall per event rose quickly and eventually surpassed that on the lysimeters with grass. After harvest both parameters dropped well below the values on the grass lysimeters again.