What is soil porosity?

Soil porosity refers specifically to the volume of voids or pores within the soil relative to its total volume. It is a crucial factor for understanding how well soil can retain water and air, which directly influences plant growth and soil health. High porosity indicates that a soil has a larger volume of spaces or pores, allowing for better air flow and water drainage, while low porosity means there is less space available, which can lead to issues with waterlogging and reduced aeration.

The other options address different properties of soil. Weight per unit volume relates to soil bulk density, which measures compaction rather than porosity. The ability of soil to conduct water refers to hydraulic conductivity, which is influenced by soil texture and structure rather than solely its porosity. The amount of organic matter is a separate aspect of soil health and fertility but does not define porosity itself. Hence, the definition of porosity focuses on the volumetric relationship between the soil's solid and pore spaces.