Which horizon is the surface layer

O humus or organic : Mostly organic matter such as decomposing leaves. The O horizon is thin in some soils, thick in others, and not present at all in others. A topsoil : Mostly minerals from parent material with organic matter incorporated. A good material for plants and other organisms to live. E eluviated : Leached of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials — missing in some soils but often found in older soils and forest soils.

The soil profile is a vertical section of the soil that depicts all of its horizons. The soil profile extends from the soil surface to the parent rock material.

The regolith includes all of the weathered material within the profile. The regolith has two components: the solum and the saprolite. The solum includes the upper horizons with the most weathered portion of the profile. The saprolite is the least weathered portion that lies directly above the solid, consolidated bedrock but beneath the regolith. There are 5 master horizons in the soil profile. Not all soil profiles contain all 5 horizons; and so, soil profiles differ from one location to another.

O : The O horizon is a surface horizon that is comprised of organic material at various stages of decomposition. It is most prominent in forested areas where there is the accumulation of debris fallen from trees. A : The A horizon is a surface horizon that largely consists of minerals sand, silt, and clay and with appreciable amounts of organic matter.

This horizon is predominantly the surface layer of many soils in grasslands and agricultural lands. E : The E horizon is a subsurface horizon that has been heavily leached. Leaching is the process in which soluble nutrients are lost from the soil due to precipitation or irrigation. This is a transition area between soil and parent material. Partially disintegrated parent material and mineral particles may be found in this horizon. It is less altered and weathered than the layers above and has less living matter.

Pike County Conservation District. Your Legacy. The B horizon or subsoil is where soluble minerals and clays accumulate. This layer is lighter brown and holds more water than the topsoil because of the presence of iron and clay minerals. There is less organic material. Look at figure 2. The C horizon is a layer of partially altered bedrock. There is some evidence of weathering in this layer, but pieces of the original rock are seen and can be identified. Not all climate regions develop soils, and not all regions develop the same horizons.