DOI: 10.5285/0c17a041-8852-4800-9c04-2ab2dd858837
title: Soil respiration responses to carbon, nitrogen and phosphorous additions to topsoil and subsoil cores from the Conwy catchment in North Wales (2014)

description: The data consists of raw data on measured carbon dioxide (CO2) and nitrous oxide concentration (N2O) concentrations from intact soil topsoil (0-15 cm) and subsoil cores (85-100 cm) to added carbon, nitrogen and phosphorus. Four land uses (Bog, acid grassland, improved grassland and arable field) in North Wales were selected for this study with three replicates each. Intact soil cores were taken in January and February in 2014.

The data consists of three datasets. The first dataset contains the measured CO2 concentration that was measured from intact topsoil cores (0-15 cm) as a result of carbon, nitrogen and phosphorus additions form a pilot study. For the pilot study intact topsoil cores were taken in November and December in 2013 from three sites. a Podzol, a coniferous forest soil and a grassland soil. These sites were not in the Conwy Catchment. The pilot study results were used to inform the experimental setup for the main experiment. The data from the main experiment, measured carbon dioxide (CO2) and nitrous oxide concentration (N2O), are reported in the second dataset for intact topsoil and subsoil cores. The third dataset contains nitrogen mineralization data from the intact soil cores that were used as control cores and did not receive any carbon or nutrient additions. The dataset contains measurements on soil nitrate, ammonium and total nitrogen mineralization rates in milligrammes of nitrogen per gramme of dry weight or per gramme of organic matter content.

In both the experimental datasets, the weight of the soil cores at field capacity (in grammes) was reported and weight loss was adjusted by adding an artificial rain water solution. The incubation time (in minutes), the measured CO2 and N2O concentrations (in part per million = ppm) were recorded at the beginning and the end of the incubation. Total soil dry weight per soil core (in grammes) and the total weight of soil organic matter (loss on ignition, in grammes) are reported. The data were collected to calculate production of Measurements were undertaken by staff from the Centre for Ecology & Hydrology. The data were collected to link plant and soil nutrients to aboveground and belowground ecosystem processes to incorporate relevant parameters into the Joint UK Land Environment Simulator (JULES) model.

This data was 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.
description: Soil cores were taken from the topsoil 0-15 cm using a soil corer with a diameter of 5 cm for the initial experiment; intact soil cores were collected in winter 2014 using a Van Walt percussion (Cobra TT) core. Soil cores were taken to a depth of 1 metre and topsoil (0-15 cm) and subsoil (85-100 cm) cores were used. 

Soil cores were kept in water tight plastic bags to prevent water loss via transpiration at 4 oC till they were adjusted to their field capacity by adding an artificial rain solution. Carbon, nitrogen and phosphorus were added in varying amounts and the result informed the nutrient additions in the main experiment. Carbon was added either as glucose only, a mix of carbon compounds simulating rhizodepsition and as glycine. Nitrogen was added as NH4NO3-N and phosphorus as KH2PO4. In the main experiment, carbon, nitrogen and phosphorus were added in a full factorial design to topsoil and deep soil cores on three consecutive days. Therefore, soils were incubated for 1 or 2 hours (bogs only) at 10 degrees Celsius , gas samples were taken and Carbon Dioxide (CO2) and Nitrous Oxide (N2O) concentrations were measured respectively. Similar incubations were carried further nutrient additions at days 4, 5, 6, 8 10 and 12.

CO2 concentrations were measured using gas chromatography (GC, Perkin Elmer Clarus 500 gas chromatograph, Waltham, MA) equipped with a Porapak QS (80e100 mesh, company, country) analytical column. CO2 standard gases with CO2 concentrations of 250, 500 and 1000 parts per million (ppm) were used to calculated CO2 concentrations in the samples. N2O and CO2 concentrations were measured simultaneously. N2O fluxes were quantified using standards at 5, 10 and 15 ppm. 

Nitrogen mineralization was measured 4 weeks after flushing off soil available nitrogen by leaching the soil cores with the artificial rain solution for 4-5 days for soil cores of the main experiment. Soil cores were incubated at 10 degrees Celsius for further 2 weeks after the nutrient addition experiment. To avoid water loss from the cores, cores were stored in breathable plastic bags. After the 4 weeks of incubation, each soil core was sieved (2 mm) and 10 grams moist soil was extracted with 100 mL 1 M KCl. The extract was then analysed for nitrate and ammonium contents (SEAL AQ2+ Discrete Analyser). The total soil dry weight (g) was measured after drying the soil at 65 degrees Celsius and the soil organic matter content was determined gravimetrically by measuring mass loss at 375 degrees Celsius after removal of stones and coarse roots. Soil nitrate, soil ammonium and total nitrogen mineralization rates were calculated as grams per dry weight and grams per organic matter content.

All results were entered into Excel spreadsheets. Results from all the analyses were combined into one Excel spreadsheet. Data were then exported from this combined Excel spreadsheet as .csv files for ingestion into the EIDC.