This data set consists of Particle Size Distribution (PSD) measurements, analysed in a sub set of soil samples with a loss on ignition lower than 50%, taken from within a range of land use types across Wales, collected as part of the Glastir Monitoring and Evaluation Programme (GMEP). Laser granulometry was used to measure the PSD. The monitoring programme was set up by the Welsh Government in 2013 to monitor the effects of the Glastir agri-environment scheme on the environment and ran from 2013 to 2016. The field survey element was based on a stratified random sampling design of 300 x 1km square sites across Wales, and was managed by the UK Centre for Ecology & Hydrology.