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The prevention and control of soil erosion

This refers to the wearing and washing away of the top soil by agents such as man, wind, water.
Factors influencing erosion:
Ø  Climate
Ø  Topography
Ø  Vegetation cover
Ø  Activities of man 

Types of soil erosion:
a.       Sheet erosion: This refers to the removal of a layer of topsoil over almost the entire land surface.
b.      Splash erosion: This refers to the removal of the topsoil  from a small area via a forceful fall of rain
c.       Rill erosion: This refers to the removal of the topsoil along narrow tracks or channels via raindrops falling on the soil.
d.      Gully erosion: This refers to the removal of the topsoil by run-off water which has not sunk into the soil. When this occurs continuously, gullies are formed.

·         Avoiding bush
·         Avoiding overgrazing
·         Mulching
·         Terracing
·         Strip cropping
·         Erecting wind and water barriers
·         Addition of organic matter

ROCKS: These are naturally occurring solid aggregate of one or more minerals. There are three types of rocks. These are:
a.       Igneous Rocks: These are rocks formed from molten lava(eruptions from volcanoes) when it cools down and solidifies. They contain primary minerals like quartz, feldspar, etc. Examples of igneous rocks are granite, quartz, gabbro and diorite.
b.      Sedimentary rocks: These are rocks formed from settling or sticking together of broken down particles of other rocks. Examples of sedimentary rocks include shale, sandstone, dolomite and limestone.
c.       Metamorphic rocks: These are rocks formed by subjecting any type of rock either igneous rocks or sedimentary rocks to different temperature and pressure conditions than those in which the original rocks were formed. Examples of this include marble, sandstone, schist, etc.

This refers to the gradual process that disintegrates, decomposes or crumbles rock into smaller rock particles by agents such as water, changes in temperature, pressure, chemicals, atmospheric oxygen, wind and roots of plants.

1.      PHYSICAL AGENTS: This refers to the mechanical breakdown of rocks into smaller particles. In physical weathering, there is no change in the chemical composition of the rock. Examples of physicals include; effects of temperature, wind, water, moving ice and pressure.
               Temperature: This refers to the degree of hotness or coldness of a place.
-          In hotter regions when the temperatures are high, rocks expand when heated and contract when cooled. The uneven expansion and contraction of rock minerals cause cracking and disintegration of rocks into smaller particles
 In colder regions when the temperature falls below freezing point, water in the crevices of rocks solidifies and expands in the process, causing the rocks to crack under stress.
     CHEMICAL AGENTS: This refers to the breakdown of rocks into smaller particles as a result of various chemical processes. Some of the agents include:
a.       Carbonation: This refers to the reaction of carbonic acid with rocks to break it down
b.      Hydrolysis: This refers to the chemical reaction between a substance and water which leads to the breakdown of bond between hydrogen and oxygen in water.
c.       Hydration: this refers to the process by which water becomes attached to the surface of a substance
d.      Reduction: This simple refers to the addition of hydrogen or removal of oxygen from a substance.
e.       Oxidation: This means the addition oxygen or removal of hydrogen
            BIOLOGICAL AGENTS: This refers to the breakdown of rocks into smaller particles by activities of living things. Agents involve in biological weathering of rocks include the following:
a.       The pressure influenced by animals such as elephant
b.      The passage of the roots of plants through cracks in rocks
c.       The boring activities of organisms such as earthworms.

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