DE-Okd is a permanent grassland site on drained organic soil located within the bog complex “Gnarrenburger Moor” in Northwest Germany, approximately 60 km north of the city of Bremen. The site has been used for fodder production over at least the last 30 years. The field is intensively managed with four to five grass cuts each year in combination with high nitrogen fertilization rates. The bog complex is located in a dairy region with about 80% of its area nowadays being used as grassland. The site is deeply drained with a horizontal drain spacing of 8 m and a drainage depth of about 0.7 m. Each drain pipe discharges into deep ditches at the edges of the field. The grass species composition consists mainly of Lolium perenne and to a lower extent of Festuca pratensis, Phleum pratense, and Poa pratensis. The soil/peat profile is classified as Ombric Drainic Fibric Histosol (Hyperorganic; IUSS Working Group WRB, 2015). Total peat depth at the site is at least 2.4 m. Peat type within the first five centimeters is amorphous peat, below 5 cm it is Sphagnum peat. In all horizons below 5 cm, the C:N ratio ranges between 48 and 76, pH values are <4, and the bulk density is <0.13 g cm-3.
