Erosion, Deposition and Soil

The movement of weathered material EROSION The movement of weathered material by: wind, water, ice or gravity.

placement of Material – soil deposited down Deposition- placement of Material – soil deposited down

big objects settle out first

denser particles settle first

due to weathering processes rocks break down into soil THE ROCK CYCLE The rock cycle is a concept that describes the transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. due to weathering processes rocks break down into soil

Soil Profile In a cross-section of soil, various zones are formed. Soil profile is somewhat like the soil's fingerprint, and it will differ from other soil based on factors like its color, texture, structure and thickness, as well as its chemical composition based on the types of weathered rocks, climate (temps & precip).

O Horizon: Organic Layer / Humus It consists of leaf litter and other organic material lying on the surface of the soil.

A Horizon: Topsoil This layer is usually dark, rich, loose and crumbly due to plant roots weathering rock with varying amounts of organic matter.

A Horizon: Topsoil Most productive layer of soil. Conservation efforts are focused here!

B Horizon: Subsoils Subsoils are usually lighter in color, dense, low organic matter, and less nutrients. Develops as rainwater washes clay and minerals from A horizon to B

C Horizon: Transition This layer of transition is almost completely void of organic matter and is made up of partially weathered parent material. Forms as bedrock weathers and breaks up into soil particles.

Bedrock Below the C horizon the unweathered bedrock will be found.

Types of Soil Sand Silt Clay Large soil particles and pore spaces Settle out first Water drains very quickly Silt Very fine “sand” (feels like flour) Holds water better than sand Feels slick and smooth when water added Clay Smallest soil grains Smallest pore spaces – water and air does not circulate Impermeable (water does not drain well if at all) Plant roots have problems penetrating

Reading a Soil Triangle

Porosity –vs- permeability Porosity – the amount of space with in a rock or between particles. Permeability – the ability that water can move through a rock or particles.

Fertility of Soil the ability of a soil to sustain agricultural plant growth i.e. to provide plant habitat and result in sustained and consistent yields of high quality In order for plants to be healthy and produce demanded yields the soil must have adequate nutrients Major required nutrients include: Nitrogen Phosphorus Potassium Less required Sulfur Calcium Iron, Etc..

As you can see the richer the soil the more plants it can support