The French Soil Quality Monitoring Network (RMQS) is a national program for the assessment and long-term monitoring of the quality of French soils. This network is based on the monitoring of 2240 sites representative of French soils and their land use. These sites are spread over the whole French territory (metropolitan and overseas) along a systematic square grid of 16 km x 16 km cells. The network covers a broad spectrum of climatic, soil and land-use conditions (croplands, permanent grasslands, woodlands, orchards and vineyards, natural or scarcely anthropogenic land and urban parkland).

The physical, chemical and biological properties of the soil are measured on each site, during the first campaign and presently on the second campaign. The spatial and temporal variability of soil properties are explained by biophysical variables, sources of contamination, history of land-use and management practices on each plot. The first sampling campaign in metropolitan France took place from 2000 to 2009. This campaign focused on soil contamination assessment and made it possible to map key soil parameters (28 variables) as well as 12 trace metal elements and 70 persistent organic pollutants. The sampling method, measurements and observations on each site are described in the RMQS guidelines. The second campaign started in 2016 and should last 12 years.

The soil tests were carried out on composite samples collected with an auger at two sampling layers: 0-30 cm or cultivated layer named “upper layer” or “layer 1” and 30-50 cm named “subsoil layer” or “layer 2”. Each composite sample was made up of 25 individual sample cores taken on a sampling area of 400 m², using an unaligned systematic sampling design (see description in the RMQS guidelines). In some cases, a third layer was made up of holorganic layers in forests or meadows, corresponding to pedological horizons OF and OH, when these layers were sufficiently thick, (at least 1 cm) and continuous over the sampling area.

On each plot, were performed, on a pit, volumetric samples to measure bulk density and coarse fragment content. Usually three pseudo-replicates corresponding to both layer 1 and layer 2 and covering the thickness of each layer were sampled. For holorganic layers, bulk density was calculated from the composite sample, for which each elementary volume was measured.

The dataset contains the results of bulk density and coarse fragment data from 2168 plots of the first campaign and their available layers and from 2137 plots of the 2nd campaign until 2022. The raw values of bulk density and coarse fragment content are not available here but corrected by layer by applying a weighting taking in account overlapping of samples.