Data were collected as part of the NERC Soil Biodiversity Thematic Programme, which was established in 1999 and was centred upon the intensive study of a large field experiment located at the Macaulay Land Use Research Institute (MLURI) (now the James Hutton Institute) farm at Sourhope in the Scottish Borders (Grid reference: NT 8545 1963). Soil samples were collected by students and staff at the experimental site before being processed according to standard protocols, with the data then being transferred to the programme data manager at the Centre for Ecology & Hydrology.