[1] Bulk density is useful for materials such as powders, granules, and other "divided" solids, especially used in reference to mineral components (soil, gravel), chemical substances, pharmaceutical ingredients, foodstuff, or any other masses of corpuscular or particulate matter (particles).
For example, a powder poured into a cylinder will have a particular bulk density; if the cylinder is disturbed, the powder particles will move and usually settle closer together, resulting in a higher bulk density.
In contrast, soils rich in soil organic carbon and some friable clays tend to have lower bulk densities (<1.0 g/cm3) due to a combination of the low-density of the organic materials themselves and increased porosity.
[4] In a detailed study which has used 6,000 analysed samples in the European Union, a high resolution map (100m) of soil bulk density for the 0-20cm using regression model.
[5] Croplands have almost 1.5 times higher bulk density compared to woodlands.