Formation composition and properties of soil

Soil can defined has unconsolidated, weathered materials found in the uppermost layer of the earth’s surface on which plant grow. In other word, soil refers to the uppermost layer of earth’s crust which provides support and nutrients for plant growth.

Soil formation is greatly controlled by five major factors which are

1. Climate.
2. Parent materials.
3. Biotic (living organisms).
4. Topography/relief.
5. Time.

Factors of soil formation

Climate

The elements of climate such as rainfall, temperature, wind and pressure are all very important in soil formation.

Temperature

The alternating heating and cooling of rocks result in the continual expansion and contraction which eventually result in cracks in the rocks and its consequent breakdown into small pieces to form soil. Temperature affects the rate of chemical weathering of rocks.

Rainfall

The action of running water from rainfall causes the gradual wearing away of rocks during erosion to form soil. Also, raindrops may break down some parents rocks to form soil. Rainfall enhances with native growth of plants whose roots cause further breakdown of rocks, why the rain water transports Rock particles after disintegration.

Wind

High wind velocity in deserts carry with it other tiny rocks which collide with one another or other rocks, resulting in the breaking town of rocks into tiny pieces to form soil. Wind also removes whether the materials, nearby exposing parent materials to further breakdown.

Pressure

High pressure on a hanging Rock may cause such rock to fall down and break into tiny pieces, resulting in the formation of soil.

Parental materials

Parental materials constitute the major materials from such soil is formed. They are Igneous, sedimentary and metamorphic rocks. Parent materials determine the chemical composition of the soil that is formed. They also contain different minerals which account for difference in the fertility of the soil formed from each of the different types. Parent materials determine the physical characteristics of the soil. Hardness of parent material affects the rate of soil formation.

Topography

1. The shape of the land that influences the movement and amount of water in the soil.
2. Hilly land sloppy surfaces which support erosion and encourages soil formation.
3. A flat land exposes the whole surface to equal environmental factors and therefore delays soil formation.
4. A topography of the land affects the distribution of plants and animals which influences the process of soil formation.
5. Most oil formation in the valleys than at the top of the hills.

Biotic factors (Living organisms)

The activities of living organisms help to speed up the process of soil formation.

1. Termite, earthworm and rodent mix the mineral and organic matter together, and this results in the formation of soil.
2. They also allow water and air into the soil which eventually reacts the rocks to cause their breakdown into soil.
3. The activities of man during tillage and other farm operations indirectly help to break rocks into tiny pieces to form soil.
4. The activities of micro-organisms which promotes decomposition of organic materials aid soil formation.
5. The roots of plants penetrate drugs and break them into tiny pieces to form soil.
6. They influence the organic matter content of the soil.
7. Organisms produce carbon dioxide which forms carbonic aid with water and enhances the weathering of rocks.
8. Microbes also improve soil aeration and water percolation. This enhances chemical and physical weathering.
9. Microbes help in the the composition of organic matter in the soil.
10. The decay of fallen leaves of trees is the aid of bacterial results in the formation of humus and this is rich in the plants food.

Time

Time also plays an important role in soil formation. It takes a long time for mature soil to be formed.

1. It takes a long time for small pieces of rocks to disintegrate into grains of soil.
2. Time also determines whether or not the soil is where developed.
3. It takes a short time in the formation of immature soil.
4. It takes time for rainfall to leach chlorides, sulphates and carbonates from the soil.
5. It how to takes a long time for plants to decay and become part of the soil.

Processes of soil formation

The process of soil formation is called weathering. Weathering is defined as the disintegration or breakdown of rocks into tiny pieces to form soil. In other words, weathering you can also be defined as the breaking down of rock masses (rock minerals) into simpler forms through the agents of physical chemical and biological processes.

The processes of soil formation include

1. Physical process
2. Chemical process
3. Biological process

Physical process

The agents of physical weathering are temperature, wind, ice, water and pressure.

Temperature

The alternating heating and cooling of the rocks produce pressure within the rocks and cause them to break down into pieces.

Wind

As a result of the grinding of rock surfaces by solid materials carried by wind, water and moving ice (glacier), rocks break down to form soil.

Ice

The conservation of water into cracks in rocks into eyes results in increase in volume. This increases in volumes results in more pressure being exerted on the rock walls which eventually break into smaller pieces.

Water

Running what are carries some fragments of rocks along its course and this rub against the surface of rocks into the river bed, thus breaking off small pieces of rocks.

Chemical process

The agents of chemical weathering include solution, carbonation, hydration, hydrolysis and oxidation.

Explanation of chemical weathering of rocks

1. Chemical weathering is the decomposition of rocks by chemical agents formed through the reaction of water with atmospheric gases such as air (oxygen and carbon dioxide).
2. As some minerals in the rocks are dissolved and others change engine new chemical products; therefore, disintegration of rocks occurs.

Discussion of chemical weathering of rocks

Hydration

1. It occurs when water combines with or binds to some minerals.
2. Intact water may bind to silicates or oxides of iron.
3. Hydrated compounds are soft and easily fragmented.
4. It does not usually affect the chemical composition of the hydrated products.