Time series data of carbon release in disintegrations per minute are presented for different nitrogen and phosphorus treatments with a high molecular weight substrate added as a carbon source to soil samples from six depths (0-15, 15-30, 50-100, 100-150, 150-200 and 250-300 centimetres). Soil cores were collected from a field experiment in the Conwy catchment in July 2016 and returned the laboratories of the School of Environment, Natural Resources and Geography, Bangor University. A high molecular weight substrate was added as a carbon source to the samples and the rate of 14C-substrate mineralization measured. All the work was carried out by trained members of staff from Bangor University and the Centre for Ecology & Hydrology. The measurements were taken to improve understanding of the relationship between microbial activity and soil properties and depth of sampling, under differing nutrient availability. The data were collected for the NERC project 'The Multi-Scale Response of Water quality, Biodiversity and Carbon Sequestration to Coupled Macronutrient Cycling from Source to Sea' (NE/J011991/1). The project is also referred to as Turf2Surf.