- The Soil System
- Soil are all over the world and is a major component of the world system
- Form of soil are rocks, living matter, air and water.
- Soil are outer layer of the Earth surface
- Soils are vital resource for humans, the should be considered as a non renewable resource because they take a long time to develop.
- Soil forming processes are add material to soil, movement of water and movement of soil solution is upwards through the soil
- Organic changes occur mostly at or near the surface.
- Plant litter is decomposed into a dark amorphous mass
- degraded gradually by fungi,algae, or small insects and worms.
- Soil structures and properties
- Soil texture depend on the differently sized materials usually sand,silt, and clay
- Agricultural soil depends on
- porosity and permeability of the soil
- pore spaces determine the rate at which water drains through a soil.
- surface area of the soil particles
- the surface of the soil have amount of water and nutrients in solution that can be retained against the force of gravity, heavy clay soil can hold twice as much water as a light soil
- porosity and permeability of the soil
- Soil structure depends on
- soil texture
- dead organic matter
- earthworm activity
- Shrinking limit: state at which the soil passes from having moist to dry appearance
- Plastic limit: occurs where each per is surrounded by a film of water sufficient to act as lubricant
- Liquid limit: occurs when there is sufficient water to reduce cohesion between the pads.
- Field capacity: maximum amount of water that a particular soil can hold.
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