Density is defined as the mass of material contained within a given volume.
For example, a shoe box full of sawdust would not have the same density as a shoe box full of lead or iron, even though they occupy the same volume in the shoe box. Density is therefore a measure of how tightly packed the soil particles are in any given pedon. We'll explore the importance of soil bulk density in the next laboratory exercise. Note that the bulk density of a soil takes into account the total soil volume, which includes the space occupied by the air in the pores. The mass of a soil is nothing more than the oven dry weight in grams.