ABSTRACT
Soil bulk density (ρb), also called apparent density, is the ratio of the mass of soil solids (Ms) to the total volume (Vt). Soil ρb is an important soil physical property and a strong determinant of soil quality because it affects other properties such as soil strength, water retention, available water capacity, porosity, and gaseous exchange. It has pedological, edaphological, ecological, and environmental significance (Figure 23.1). Pedologically, it affects numerous soil processes, including transport of water and dissolved/suspended substances leading to eluviation and illuviation. Edaphologically, it affects plant growth both directly and indirectly. Ecologically, ρb affects and is affected by activity of diverse soil fauna and flora. Environmentally, it affects quality of surface and ground waters, and fluxes of greenhouse gases (GHGs) between soils and the atmosphere.
