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geocology
soils
Term | Definition |
---|---|
Composition of soil | Mineral particles, Organic matter, air and water |
Mineral particles | It includes stones, sand, silt and clay. It comes from broken down rock by weathering and erosion over long periods of time. |
Organic Matter | It consists of remains of plants and animals as well as living creatures. When material such as leaves needles bark and twigs falls to the ground it is known as plant litter. |
Air and water | It is found in the pores between the particles of soil loose sandy soils have more pore space and tightly packed clay soils. |
Soil Characteristics | -Texture -Structure -Ph value -Organic matter -Moisture -Colour |
Soil Texture | Sand largest coarsest particles. Feels gritty. Silt are medium size. Feel soft and silky. Clay particles smallest and smoothest particles. Fell sticky. |
Sandy Soils | Some silt and clay. Water drains away freely. Nutrients can be leached. |
Silty Soils | Clay and sand. Fertile. When wet they are heavy and are poorly drained |
Clay soils | Wet and become waterlogged. When dry they shrink and crack. Difficult for plant roots and water to penetrate the ground |
Loam soils | Best type. Roughly the same amounts of sand silt and clay. It retains nutrients producing a very fertile soil. |
Soil structure | Way soils are bound together into small clumps called peds. Crumb platy blocky |
Crumb | Small rounded grains similar to breadcrumbs. Excellent for draining and air movement |
Platy | Thin flat particles often overlap. Usually found in compacted soils. Hold up water movement. |
Blocky | Cube shapes fit tight together. Few pore spaces for roots and air to pass through. |
Humus | A thick jelly like dark coloured substance |
Ph of soil | degree of acid or alkaline |
Alkaline soils | High ph level Limey and contain high levels of calcium |
Neutral soils | ph of llevel 7 |