Cognettia sphagnetorum (Enchytraeidae) and nutrient cycling in organic soils: a microcosm experiment

A microcosm experiment was carried out to investigate the role of enchytraeids in nitrogen and phosphorus mineralisation in an organic grassland soil. Soil cores were taken from a cambic stagnohumic gley with associated vegetation in the Moor House National Nature Reserve (UK), defaunated, separated into 3 cm layers and inoculated with Cognettia sphagnetorum (Vejdovsky) in microcosms, maintained at 15 degrees C in the laboratory. The leaching of dissolved organic nitrogen (DON), ammonium and phosphorus (total, organic and soluble reactive phosphorus) was monitored over 8 weeks, and found to be significantly greater in the presence of C. sphagnetorum; this effect varied with soil depth, highest increases being found in the 0-3 and 3-6 cm soil layers. The pH in the leachates was also increased in the presence of Cognettia. The impacts of seasonal vertical distribution of enchytraeids on nutrient cycling are discussed, together with the implications of climate change in these systems. (C) 1998 Elsevier Science B.V.