This dataset consists of measures of topsoil (0-15 cm) physico-chemical properties from 575 soils sampled from 146 x 1 km squares across Great Britain collected in winter 2021 as part of the UKCEH Countryside Survey. The properties included are: pH, soil organic matter (loss on ignition, LOI), derived carbon concentration and carbon stock from LOI (SOC), soil group, soil bulk density of fine earth, soil moisture of wet soil, fine earth volumetric water content (dry), and nitrogen concentration and stock. The UKCEH Countryside Survey is a unique study or 'audit' of the natural resources of the UK's countryside. The sample sites are chosen from a stratified random sample, based on a 15 by 15 km grid of GB. Surveys have been carried out in 1978, 1984, 1990, 1998 and 2007 by the UK Centre for Ecology & Hydrology (UKCEH) and predecessors, with repeated visits to most of the squares. The countryside is sampled and surveyed using rigorous scientific methods, allowing us to compare new results with those from previous surveys. In this way, we can detect the gradual and subtle changes that occur in the UK's countryside over time. In addition to soil data, vegetation species data are also gathered by the current phase of the UKCEH Countryside Survey. This work was supported by the Natural Environment Research Council award number NE/R016429/1 as part of the UK-SCAPE programme delivering National Capability and through the UKCEH National Capability for UK Challenges Programme NE/Y006208/1. Full details about this dataset can be found at https://doi.org/10.5285/38d6f5b4-4d03-4006-aa55-91894378ef27