Wethering In Agriculture

Weathering can be defined as breaking down of rock into smaller particles to form soil. 

Add caption

There are three types of weathering:

1.   Physical weathering  

2.   Chemical weathering  

3.   Biological weathering  

PHYSICAL WEATHERING  

Various agents of physical weathering   include:

a.    Temperature:  Rock expands when temperature is high during the day and contrasts at night when the temperature cools down. As a result of continuous expansion and contraction rock becomes weakened and broken down into small pieces to form soil

b.   Ice: When water accumulates in the hollow of a rock the volume increases when water freezes, this increase forces the rock to expand and the rock contrast when the temperature is high and some of the water sink into the crack of the rock. when this continues for a long time the rock becomes weak and disintegrate to form soil.

c.    Water: Running water do carry materials such as rock particle, when such particles are rubbed against one another they further breakdown into smaller pieces to form soil.

d.   Wind: A moving air is called wind, when air is moving it carries along sand particles. When these sand particles blow against a rock it breaks down the rock through a gradual process to form soil.

e.    Human Activities: Human activities such as road construction, construction of building e.tc. leads to the breaking down of rocks for use, the unused particles now form soil.

f.     Pressure: Pressure exerted by human beings or animals on rock is capable of breaking it down to form soil.

CHEMICAL WEATHERING

This can be referred to as changes in the composition of rock materials which is brought about by chemical oxidation.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

a.    Carbonation:  Rain water that passes through atmosphere combines with Co₂ to form a weak acid known as carbonic acid. When carbonic acid comes in contact with rock especially marble rock it breaks it down to form soil.  C0₂ + H₂0              H₂C0₃ 

b.   Oxidation and reduction: Oxidation is the addition of oxygen to a substance while reduction is the removal of oxygen from a substance. Rock and minerals that contains iron and manganese are subjects to chemical weathering by oxidation and reduction.

c.    Hydration: This is the combination of water with another substance and the hydrated substance formed increases in volume thereby increasing or hasting the weathering process clay and ironite are hydrated this way:

Fe₂0₃  + 3H₂0             Fe₂0₃  3H₃0          

CuS0₄  + 5H₂0           CuS0₄  5H₂0          

d.   Hydrolysis:  Water causes reaction in a chemical reaction with the soil. Water reacts with carbonate and stimulates a double decomposition type of reaction.

Na₂C0₃  + 2H₂0             2Na₂0H  + H₂C0₃        

3M_g  + CS0  + 2H₂0            

e.    Solution: Water is able to dissolve an easy soluble universal in the rock and carry it away through drainage; if there is no drainage such mineral accumulates to form a particulars soil.

BIOLOGICAL WEATHERING

The pressure exerted on rocks by animals such as elephant, cattle and human beings moving about causes smaller fragment of rock to disintegrate or breakdown. The activities of earthworm, termite and other soil organisms have similar effects on the rock. The root of growing trees may penetrate the cracks in the rock and exert considerable pressure which leads to the breakdown of the rock.