What is soil?
Soil is made of physical, biological, and chemical components and it is how these components interact that determine a soil's characteristics.
The solid components of soil include minerals, organic matter (OM), and biota (organisms living in the soil). Pores in the soil can be filled with water, air, and/or biota. Healthy soils consist of a range of pore sizes (small, large, and intermediate pores).
Mineral solids determine texture and help quantify soil functioning. Mineral composition includes sand, silt, and clay and it is the proportion of these components that is used to classify soil.
Although only a small portion of soil consists of biota, it is estimated that there are more species of organsims in a shovel of soil than above ground in the entire Amazon rain forest (NRCS). Biota play a significant role in soil health as soil food webs influence soil functioning.