The bulk density is the weight of a soil in a given volume. The bulk density is influenced by the composition of the soil material, organic matter content, and the degree of compaction. Bulk density is reported in the method section of the Soil Carbon Check and plays a vital role in the background: to calculate carbon / CO2 storage per hectare, the total mass of soil should be known (derived from bulk density). Eurofins Agro uses a pedotransfer function developed by Hollis et al. (2012) to predict bulk density based on analysed soil characteristics, in which particle size and organic carbon content are the biggest factors.