3 Concepts of Soil

Pedon
the smallest volume that can be called a soil. It has three dimension. It extends downward to the depth of plant roots or to the lower limit of the genetic soil horizons. Its lateral cross section is roughly hexagonal and ranges from 1 to 10 m in size depending on the variability in the horizons.

Profile
a vertical sections of the soil through all its horizons and extending into the parent material.

Horizon
a layer of soil, approximately parallel to the soil surface, differing in properties and characteristics from adjacent layers below or above it.