By: Stephanie Bales, Kelley Fox, and Courtney Dunford Composition of Soil By: Stephanie Bales, Kelley Fox, and Courtney Dunford

Soil comes from rocks, minerals, and organic materials Components of soil: mineral matter, air, water, organic matter Cause of soil erosion: water, wind, no vegetation

Words To Know Clay: fine grain soil that is pliable when moist but hardens as it is heated Compost: decomposed organic material Loam: a soil containing clay, sand, silt and organic matter Metric system: a system of measurement based on powers of ten Sand: loose particles of broken rock Silt: particles of rock slightly larger than clay but smaller than sand Topsoil: upper layer of soil, plant roots are typically found here

Rock Material Stone, sand, silt and clay Comes from “parent rock” Parent rock determines the chemical back bone of the soil It also determines the grain size Topography, time and climate effect composition and the breakdown of the rock It may appear as pebbles, gravel, or as small as particles of sand or clay.

Organic Material Plants, animals, fungi, bacteria and humans affect the composition of the soil Decaying of once-living organisms (plants or insects) Fungi and bacteria affect the exchange of nutrients between plants and soil Humans remove vegetation which causes erosion. This is plants or animals that have died and decayed until they become part of the soil.

The amount of water in the soil is closely linked with the climate and other characteristics of the region. The amount of water in the soil is one thing that can affect the amount of air. Very wet soil like you would find in a wetland probably has very little air. The composition of the soil affects the plants and therefore the animals that can live there.

Layers of Soil Defined by color, size, texture, structure, consistency, root quantity, ph and other factors

5 Layers Top Layer – “O” – Organic Found in forest soils Made of dead leaves and debris 2nd Layer – “A” – Organic Material is mixed with Inorganic Material Usually darker, and if it’s tere means the soil is fertile for plants 3rd Layer – “E” – result of acidic water running through 1st 2 layers 4th Layer – “B” – Minerals an clay grains accumlte here – can be thick and tight – difficult for water to penetrate 5th layer – “C” – contains the parent inorganic material (rock) If there wasn’t soil there wouldn’t be plant life on the surface of the land

Stages in the Formation of Soil