Lecture 5 and beyond:

Field-Based Properties of Soils: Soil Morphology and Horizon Nomenclature

 ESPM 121

For the next few lectures, we will focus on the "anatomy" of soils as seen in the field, the properties observed and quantified to distinguish soil horizons, and the nomenclature used to label or name soil horizons.

Field based soil properties that are important to identifying horizons and that are included on field sheets (see field sheet on web) (1) color (see Munsell color sheet on web), (2) structure (see web site), (3) texture, (4) consistence, (5) pH, (6) gravel, (7) carbonate, (8) horizon distinctness and several others. Each property reflects some interesting and important soil processes that will be introduced and discussed further throughout the course.

The soil horizon nomenclature, like the properties described in the field, has evolved over the past century as ideas about soil formation have developed. Right now, the US uses a system that has been in place (with modification) for more than 50 years. Soil horizon 'names' are based on an "A,B,C " system, where horizon symbols denote important processes or properties that are suspected for that layer. The key to horizon naming lies in comparing the properties of that horizon to the parent material. Considerable introductory discussion of these processes will be made at this point, but many topics will be greatly expanded later in the course.