A Basic Soil Horizon Understanding

Soils is a massive subject that, as a species, we have barely scratched the surface of. Like permaculture, it is a study that once a door is opened, 16 more doors appear –  take one of those – 32 more doors and the rabbit hole becomes apparent. When getting into farming, gardening, pasturing, and food forestry it is wise to have, at minimum, a basic understanding of soil horizons and how to identify them on your property (or the property you are working on).
Soil Horizons Explained:
O Horizon
This layer is the organic material layer. Where all the living, decaying, and decayed material settle (leaf, herb, and grass litter as well as humus). This is a crucial layer in permaculture for building and storing life. If we compared this layer of the earth to that of an orange, it would be “the thought” of the idea of the shine on the orange.
A Horizon
The A layer is the top soil. This is the first store house of nutrients below the organic material and is usually a very dark colored layer. Seeds most often germinate here and plants set roots in mass in this layer.
E Horizon
This is the eluviation (leaching) layer. This layer is usually lighter in color and mostly sand and silt. As water percolates through the above two layers, and reaches the eluviation layer, it loses much of it’s clay, nutrients, and minerals to the below layer.
B Horizon
This is the subsoil. The subsoil is where many mineral and and clays will reside. Water usually becomes mineralized by the time it reaches this layer because it is “filtered” through the above three layers. Some souble dig gardeners will highly recommend NOT to mix subsoil with top soil when planting and double digging. Plant and tree roots still thrive in this layer.
C Horizon
This layer is the regolith layer. This layer is slightly broken up bedrock. Plant roots are hardly found in this layer and only very little organic material is usually found here.
R Horizon
This is the bedrock. Mostly unweathered and often not very penetrable and impermeable. In a permaculture system that uses swales – this is the layer that will send water plumes horizontal to give rise to springs in the lower parts of the landscape.
Learn a Basic Soil Understanding here.