Data was collected as part of a study (“Waterbuddies”) of grassland agroecosystems of the northwest German (NWG) coastal region. Similar to the study of phosphorus in this context (Rotenhagen & Giani 2024; Rotenhagen et al. 2025), the aim of the study was to identify the sources and discharge paths of nutrients like ammonium and nitrate that play an important role as contaminants for surface waters and the North Sea. A dense ditch network is characterizing the NWG coastal region. These are connecting the agricultural areas directly with surface waters. Representative for the NWG coastal region, the Jade catchment area was selected to represent different landscape areas. The landscapes are divided into the geest with mostly sandy soils (Geest), the peatlands with bogs (Hochmoor) and fens (Niedermoor) as well as the marsh (Marsch) with a predominance of clay-rich soils. Furthermore, two transition sites were identified. With an oragnomineral character both consist of high amounts of organic matter and are increasingly characterized by clay in the transition to the marsh (ÜMoMa) or increasingly characterized by sand in the transition to the geest (ÜGeMo). Besides drainage ditches, grassland areas are often additionally drained. On the one hand via surface drainage mainly used for clay soils and on the other hand via drainage pipes used in sandy and organic-rich soils. The surface drainages of sandy soils differ from those installed in clay soils. Here, surface drainages are temporary installed during the runoff period without an end pipe. This way, stagnating water on the field plots are drained as needed. These additional drainages mark an important second discharge path for nutrients. Ammonium-N and nitrate-N contents of soils and ammonium-N and nitrate-N concentration of discharge and ditch waters were determined to get a further insight into how different factors (soil type, surface vs. subsurface drainage) are influencing the N-dynamics of the ditches as surface waters of the intensively drained coastal region of NWG.