Density is the weight per unit volume of an object. Particle density is the density of only the mineral particles that make up a soil; i.e., it excludes pore space and organic material. Particle density averages approximately 2.65 g/cc (165 lbm/ft3). Soil bulk density, a dry weight, includes air space and organic materials of the soil volume. A high bulk density indicates either compaction of the soil or high sand content. The bulk density of cultivated loam is about 1.1 to 1.4 g/cc (for comparison water is 1.0 g/cc). A lower bulk density by itself does not indicate suitability for plant growth due to the influence of soil texture and structure.

Representative bulk densities of soils. The percentage pore space was calculated using 2.7 g/cc for particle density except for the peat soil, which is estimated.
Soil treatment and identification Bulk density g/cc Pore space %
Tilled surface soil of a cotton field 1.3 51
Trafficked inter-rows where wheels passed surface 1.67 37
Traffic pan at 25 cm deep 1.7 36
Undisturbed soil below traffic pan, clay loam 1.5 43
Rocky silt loam soil under aspen forest 1.62 40
Loamy sand surface soil 1.5 43
Decomposed peat 0.55 65

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