Particle Density (Dp)

          Soil particle density is a measure of the mass per unit volume of the soil solids only.

•   Texture and structure do not affect particle density.

•    However, organic matter, which is a soil solid, readily influences particle density. Organic matter weighs much less per unit volume than soil minerals.

•   Soils high in organic matter have lower particle densities than soils similar in texture that are low in organic matter.

•   Soil particle density generally increases with soil depth because of the concurrent decrease in organic matter

•   Particle density varies with the type of soil minerals present as well as the amount of organic matter.

•    The particle density of most mineral soils is in the range of 2.60 to 2.75 Mg m-3. Particle density is used in the calculation of pore space and bulk density on a coarse fragment free basis.

•   When unknown, particle density of mineral soils is assumed to be 2.65 Mg m-3. Generally quartz, feldspars, and colloidal silicates dominate the mineral fraction of soils.

•   The particle density of these minerals averages about 2.65 Mg m-3. When large amounts of heavy minerals, such as hornblende or magnetite, are present, the soil particle density is greater than 2.65 Mg m-3.

•   Soils formed in volcanic parent materials, such as pumice or ash; generally have particle densities less than 2.65 Mg m-3.

•    Soil particle density is determined using  Archimedes Principle.