Provenance & quality
Soil cores were collected from the field site and returned to laboratories of the School of Environment, Natural Resources and Geography, Bangor University.
In the laboratory soil cores were divided into depth intervals of 0-15, 15-30, 50-100, 100-150, 150-200 and 250-300 centimetres and passed through a 5 millimetre sieve in order to remove stones and any plant material and to ensure sample homogeneity.
To measure the rate of 14C-substrate mineralization, 5 grams of soil (dry weight equivalent to account for soil water content variability down the soil profile) was placed into sterile 50 ml polypropylene tubes. To determine the rate of 14CO2 evolution, 50 microlitres (µl) of 14C-glucose labelled nutrient solution was added to the soil surface. Immediately after nutrient addition, a vial containing 1 millilitre (ml) Sodium Hydroxide (NaOH) trap (1 Molar (M)) was added into the polypropylene tubes to capture 14CO2 evolved. The tubes were hermetically sealed and incubated at 10 degrees Celsius to represent the mean annual temperature of the catchment. The NaOH traps were changed after 0.5, 1, 2, 4, 6, 24, 48, 72, 96, 120, 144, 168, 192, 336, 504, 672, 840 and 1008 hours and then weekly up to six weeks after initial 14C-labelling for the glucose-C additions. On removal, the NaOH traps were mixed with Optiphase HiSafe 3® liquid scintillation fluid (PerkinElmer Inc.) and the amount of 14CO2 captured was determined using a Wallac 1404 liquid scintillation counter (Wallac EG & G).
Data were entered into an Excel spreadsheet and exported as a .csv file for ingestion into the EIDC