Characteristics of the Environment - Field Sampling: Principles and Practices in Environmental Analysis - page 42

FIGURE 2.7 Equations for calculating a soil's percentage of solids and void
space. In Equation 2A r is the radius of the sampling ring and h is the
height.

TABLE 2.4 Common Soil Bulk Densities

Bulk density
(Mg/m 3 )

Void
volume (%)

Soil type Condition

1 or less 62 Indicates organic soil or soil with

high organic matter contact

Light in weight subject to
wind and water erosion

1.25 52 Common average bulk density for

agricultural soils

Good structure

1-1.6 62-39 Normal range for soils Good to poor ped structure

1.5 and above 43 Usually clayey soils Compacted limited water

movement through soil

1.7 and above 35 Usually clayey Compacted

Source: Ref. 17.

situations one may find layers of soil with different bulk densities. The density of the
layers must be known if one wishes to obtain comparable samples (on a weight basis). To
obtain the same amount of soil solid and the contaminant it contains, it is essential to take
different volumes of soils, so that the mass of solid obtained is equivalent. This would
mean that the volume of sample would need to be different for the different layers. This
type of calculation is illustrated below.

Calculating Volume of Soil Needed for Equal Mass of Samples

A soil with a bulk density of 1.2 Mg/m 3 is to be compared to a soil layer
with a bulk density of 1.5 Mg/m 3 . The sampler being used has a cross-
sectional area of 5 cm 2 . The sampler itself is 30 cm long. How many