Soil Characteristi cs Regolith The layer of rock

Soil

Characteristi cs • 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 1. 2. 3. 4. Mineral matter (broken-down rock) Organic matter (humus) Air Water Good soil = at least 50% mineral and organic matter!

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

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 1. Parent material- the source of the mineral matter. 2. Time- the longer it forms, the thicker it gets. 3. *Climate*- has the greatest effect. ● Similar soils can be made in the same climate, even if they have different parent material!

Soil Formation 4. Organisms. Factors - aid fertility -plants- main source of organic matter -microorganismsdecomposition -burrowing animalsmix things up!

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

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

3 Main Horizons • A Horizon – called topsoil 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)

Soil Erosion 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!