SOIL NCES: 6.E.2.3 & 2.4 Kim Lachler Updated 11/11/14

Soil Composition Consists of: Consists of: Weathered rock Weathered rock Decayed organic matter Decayed organic matter Mineral fragments Mineral fragments Water Water Air Air

Soil Composition Organic Matter Majority of it is dead vegetation Majority of it is dead vegetation Rest is dead animals and micro-organisms Rest is dead animals and micro-organisms Humus Humus is dark material made from organic matter is dark material made from organic matter provides nutrients for plants provides nutrients for plants

Soil Composition There are spaces between the particles of soil There are spaces between the particles of soil When the soil is dry they are filled with air When the soil is dry they are filled with air When the soil is wet they are filled with water When the soil is wet they are filled with water

Soil Texture The size of the particles of the rocks and minerals makes up the texture. The size of the particles of the rocks and minerals makes up the texture. Clay  Silt  Sand  Gravel  Rock Clay  Silt  Sand  Gravel  Rock Clays feel sticky. Clays feel sticky. Silt feels smooth. Silt feels smooth. Sand feels gritty. Sand feels gritty. Loam soil Loam soil a soil with roughly equal proportions of sand, silt, and clay. a soil with roughly equal proportions of sand, silt, and clay.

Soil Profile Soil Profile Soil Profile Is made up of all the layers of soil Is made up of all the layers of soil Horizons Horizons What the layers of soil are called What the layers of soil are called Most soil profiles have 3 horizons Most soil profiles have 3 horizons

Soil Profile A horizon A horizon Also known as topsoil Also known as topsoil Top layer Top layer Many be covered with litter (leaves, twigs, etc) Many be covered with litter (leaves, twigs, etc)

Soil Profile B horizon B horizon Middle layer Middle layer Lighter in color Lighter in color Less fertile (less nutrients) Less fertile (less nutrients) Has the most leached material Has the most leached material Leaching – Leaching – when minerals are dissolved in water in the A horizon and carried down by the water to the B horizon. when minerals are dissolved in water in the A horizon and carried down by the water to the B horizon.

Soil Profile C Horizon C Horizon Bottom horizon Bottom horizon Made from weathered rock Made from weathered rock Contains little leaching or organic matter Contains little leaching or organic matter What is under the C Horizon? What is under the C Horizon? Bed rock Bed rock

Soil Formation There are 5 factors that affect soil formation There are 5 factors that affect soil formation Climate Climate Parent material Parent material Vegetation Vegetation Slope Slope Time Time

Soil Formation Climate Climate Dry climates have less organic matter thus thinner soils than wetter climates Dry climates have less organic matter thus thinner soils than wetter climates Cold climates also have less organic matter thus thinner soils the temperate climates Cold climates also have less organic matter thus thinner soils the temperate climates

Soil Formation Vegetation Vegetation Areas with lots of vegetation like parries and forest have more organic matter, therefore richer top soils Areas with lots of vegetation like parries and forest have more organic matter, therefore richer top soils Richer top soils encourage more vegetation growth Richer top soils encourage more vegetation growth so which came first? so which came first?

Soil Formation Parent rock Parent rock The minerals that make up the bedrock is what determines the minerals in the soil. The minerals that make up the bedrock is what determines the minerals in the soil. This will affect the type of vegetation This will affect the type of vegetation

Soil Formation Slope Slope Since gravity pulls things down hill Since gravity pulls things down hill Soils near the top of a slope are thinner Soils near the top of a slope are thinner Soils near the bottom of a slope are thicker Soils near the bottom of a slope are thicker

Soil Formation Time Time The longer the bed rock has been weathered the more minerals will be in the soil. The longer the bed rock has been weathered the more minerals will be in the soil.

Bibliography Glencoe Glencoe Google images, soil, accessed 11/21/2011 Google images, soil, accessed 11/21/2011www.googleimages.com Google images, humus soil, accessed 11/21/2011 Google images, humus soil, accessed 11/21/2011www.googleimages.com Google images, leaching soil, accessed 11/21/2011 Google images, leaching soil, accessed 11/21/2011www.googleimages.com Colorado state University Extension, CMG garden notes, accessed 11/11/14 Colorado state University Extension, CMG garden notes, accessed 11/11/14http://