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on 3 October 2012

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Transcript of Soil

What is soil? When rocks are worn away,by rain,sun,wind and frost, tiny grains of rock are broken off make up much of soil. The soil are important for the planet. The soil provide plant thet are very important. Soil Forming The formation of soil happens over a very long period of time. It can take 1000 years or more. Soil is formed from the weathering of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter. Over time this creates a thin layer of soil. Plants help the development of the soil. How? The plants attract animals, and when the animals die, their bodies decay. Decaying matter makes the soil thick and rich. This continues until the soil is fully formed. The soil then supports many different plants.
The O horizon consists of freshly dead and decaying organic matter—mostly plants but also small (especially microscopic) animals or the occasional rigid cow. A gardener would call this organic matter (minus the cow) compost or humus. Below the O lies the A horizon, or topsoil, composed of organic material mixed with soil particles of sand, silt, and clay. Frolicking earthworms, small animals, and water mix the soil in the A horizon. Water forced down through the A by gravity carries clay particles and dissolved minerals (such as iron oxides) into the B horizon in a process called leaching; therefore, the A is known as the Zone of Leaching. These tiny clay particles zigzag downward through the spaces (pores) between larger particles like balls in a Japanese pachinko game. Sometimes the lower half of the A horizon is called the E (Eluvial) horizon, meaning it is depleted of clay and dissolved minerals, leaving coarser grains. Soil Profile Horizons Soil Soil Types Sand, silt, and clay are the basic types of soil. The type of soil varies from place to place. Some soils are made up lots of tiny grains stuck close together. The best soils contain some clay, some sand, and lots of humus. A soil like this is called loam. Soil Types Soil Composition Soils are a mixture of different things; rocks, minerals, and dead, decaying plants and animals. Consists of organic and inorganic materials, water and air. The inorganic materials are the rocks that have been broken down into smaller pieces. The organic material is decaying living matter. The composition of the soil affects the plants and therefore the animals that can live there. Experiments 1-Soil contains water By: Rocio Diaz Vidal, Renata Masallera, Amal Fathalla, Brisa Scandroglio
Thanks for seeing our presentation What is Humus? Humus is mostly made up of death plant
material which is slowly rooting.
Humus helps to keep the soil in good condition in different ways. For one thing,
it breaks down to give chemicals which help plants to grow Clay: less than 0.002mm
Silt: 0.002-0.05mm
Sand: 0.05-2mm When freshly-dug soil is left in a dry place, it slowly loses weight. The moisture in it slowly evaporates.
Soil moisture is important. 2-Soil contains air When soil is covered with water the water level slowly drops. The water slowly soaks into the soil and the air escapes.
This air in soil is important, too. Oxygen is needed by the roots of plants, and by soil animals. 3-If you shake up soil with water Humus The grains clay settles slowly The sand grains settle quickly
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