Apparent Density (pb)

Definition - What does Apparent Density (pb) mean?

Apparent density (pb) is the ratio between the apparent volume and dry specimen mass of a soil sample. The volume is limited by external specimen forces which include voids. Therefore, it is measured in kilograms per cubic meter (kg/m3).

This can be represented by the equation:

    pb = (md/ms – mh) × pw (kg/m3)


    pw = water density in kg/m3
    mh = saturated specimen mass in water
    md = dry specimen mass
    ms = standard specimen mass in air

Corrosionpedia explains Apparent Density (pb)

Apparent density reflects the ability of soil to provide proper structural support, soil aeration as well as solute and water movement. It is also utilized to convert between soil volume and weight. It can be used to express soil biological, chemical and physical measurements on the basis of volume for the accurate assessment and comparison of soil in management systems.

This measurement of apparent density can help solve issues that result from poor function. For instance, high levels of high apparent density indicate low soil compaction and porosity. These problems could lead to poor movement of water and air into the soil, poor growth of plants, higher chances of erosion and soil runoff. To prevent these, apparent density levels should be monitored accurately and methods implemented such as reducing soil production activities and disturbance activities.

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