Soil

Characteristics Regolith - The layer of rock and mineral fragments that cover almost all land as a result of weathering. Soil is the part that supports the growth of plants.

Soil Composition Mineral matter (broken-down rock) Organic matter (humus) Air Water Good soil = at least 50% mineral and organic matter!

Make sure you know how to read this soil chart!! Texture Soil has different particle sizes. Texture supports ability for plant life. Loam (in the center) is best because it holds water Make sure you know how to read this soil chart!!

Soil Chart What type of soil is made up of 20% clay, 40% silt and 40% sand? Medium Loam What type of soil is made up of 40% clay, 40% silt and 20% sand? Clay What type of soil is made up of 30% clay, 10% silt and 60% sand? Sandy Clay Loam

Soil Formation Factors Parent material- the source of the mineral matter. Time- the longer it forms, the thicker it gets. *Climate*- has the greatest effect. ● Similar soils can be made in the same climate, even if they have different parent material!

Soil Formation Factors Organisms- aid fertility -plants- main source of organic matter -microorganisms-decomposition -burrowing animals- mix things up!

Soil Formation Factors Slope - Steep or flat? flat areas = little erosion & drainage steep slopes = greater erosion

Soil Profiles Soil Profiles- show the characteristics from the surface down. Soil Horizons- each individual zone

3 Main Horizons A Horizon – called topsoil B Horizon – called subsoil Consists mostly of organic matter, lots of insects, fungi and microorganisms – where most decomposition takes place B Horizon – called subsoil Consists of clay particles washed out of A horizon C Horizon – Consists of weathered parent material (rock)

Water is a big factor…it causes the most soil erosion! But so are WE… Human activities remove the vegetation that covers soil! Without cover, the soil is EASILY eroded!