DOI: 10.5285/f3118fa8-6bec-488b-9713-2415912b8b9e
title: Single time point sampling of site characteristics, soil parameters and soil greenhouse gas emissions for extensive and intensive sheep-farming sites in North Wales and Devon, 2016

description: The data pertains to a single time point 'snapshot' spatial sampling of site characteristics, soil parameters and soil greenhouse gas emissions for two sites (Extensive and Intensive). The extensively managed site ('Extensive'; 240-340 m above sea level; a.s.l.) consisted of an 11.5 ha semi-improved, sheep-grazed pasture at Bangor University's Henfaes Research Station, Abergwyngregyn, North Wales (53°13'13''N, 4°0'34''W). The intensively managed site ('Intensive'; on average 160 m a.s.l.) was a 1.78 ha sheep-grazed pasture located in south-west England, at the North Wyke Farm Platform (NWFP), Rothamsted Research, Okehampton, Devon (50°46'10''N, 30°54'05''W). At the Extensive site soil and gas sampling was conducted on 30th November 2016. At the Intensive site soil and gas sampling was conducted on 1st August 2016. The data contains: site characteristics including elevation, slope, compound topographic index, vegetation type or manure application, and sample point grid references; soil parameters including soil bulk density, soil percentage water-filled pore space, soil moisture,  soil organic matter contents, soil pH, soil nitrate nitrogen concentration, soil ammonium nitrogen concentration, soil percentage total carbon contents, soil percentage total nitrogen contents, and carbon to nitrogen content ratio; and soil greenhouse gas flux data for nitrous oxide, carbon dioxide and methane. The study was conducted as a wider part of the NERC funded Uplands-N2O project and BBSRC-supported Rothamsted Research, North Wyke Farm Platform (Grant Nos: NE/M015351/1, NE/M013847/1, NE/M013154/1, BBS/E/C/000J0100, BBS/E/C/000I0320, BBS/E/C/000I0330). Quantifying the spatial and variability of the drivers of greenhouse gas emissions and their interactions in grazing systems is critical to improve our understanding of nitrous oxide, carbon dioxide and methane fluxes, enabling better estimates of aggregated greenhouse gas emissions and associated uncertainties at the landscape scale.
description: Intensive site. In order to sample the fields rapidly, minimising time differences between sampling points, sampling was conducted by teams of trained researchers (Extensive site, a team of five, sampling 22-24 points each; Intensive site, a team of four, sampling 24-25 points each) following pre-planned sampling routes and standardised sampling protocols. At the Extensive site, the team started by walking their individual assigned routes and placing chamber lids and gas sample vials next to each chamber. Upon all returning to their starting sample points, greenhouse gas sampling commenced (taking place between the hours of 10:40 am and 12:40 pm). Chamber headspaces were mixed by three syringe pumps prior to withdrawing a sample (25 ml) at 0 min and 60 min after chamber lid closure. Samples were injected into pre-evacuated 20 ml glass vials. Vials were over-pressurised as a quality control measure, to ensure sample vials had held their seal, (i.e. vials were returned to atmospheric pressure prior to analysis by inserting a syringe and needle, if the syringe plunger pushed back 5 ml it indicated that the vial had held its seal). At the Intensive site, samples (20 – 22 ml) were withdrawn from the chambers 40 min after lid closure and injected into pre-evacuated 20 ml glass vials. Chamber baseline (0 min) concentrations were approximated by background measurements (n=10, five before chamber sampling and five after) taken by manually sampling the atmosphere 1 m above the ground around the field. Bulk density cores (100 cm3, 0-5 cm at the Extensive site; 0-10 cm at the Intensive site) and soil samples (four 0-5 cm cores (bulked) at the Extensive site; six 2.5 cm-diameter, 0-10 cm cores (bulked) at the Intensive site) were taken from within the chamber areas. Bulk density cores and soil samples were stored in polythene bags in refrigerators (at 4 deg C) prior to analysis. Extensive site soil extractions and pH measurements were conducted within 24 h of sample collection, while analyses for Intensive site samples were completed within five days. 

The Extensive site was not flown as part of the project as 1m LIDAR data were created by the Environment Agency Geomatics group and available under the Open Government Licence from Natural Resources Wales (https://datamap.gov.wales/) . The data therefore contains Natural Resources Wales information, © Natural Resources Wales and database right, all rights reserved (Licence: http://nationalarchives.gov.uk/doc/open-government-licence/version/2/). At the Intensive site, the 1 m LiDAR grid was created by the Tellus South West project (https://catalogue.ceh.ac.uk/documents/b81071f2-85b3-4e31-8506-cabe899f989a). Readers are directed to the supporting documentation for further analytical details and quality control procedures for the measurements undertaken.