Soil and It's Profile Types,Layers of soil | study science

SOIL

Soil is mixture of organic matter, minerals, gases, liquids and organisms. It is one of most important natural resources and act as medium for plant growth. Soil is a protector from water loss problems. It provides anchorage to the plants and supplies water and nutrients.

 

Layers of soil

 

Soil profile

 Different layers of soil are called horizons. The arrangement of these horizons in  a soil is known as a soil profile or a soil profile consists of several soil horizons.

 Soil typically have 6 horizons from the top down. Horizon O, A, E, B, C and R. Each horizon has different characteristics.

1.      1. O  Horizon – The top, organic layer of soil. Made up of plant litter and humus.

 

2.      2. A  Horizon  ­-  This layer is called top soil.

• This horizon is generally dark in color as it is rich in humus and minerals.
•  Humus make the soil fertile and provides nutrients to growing plants.
•  This layer is generally soft, porous and can retain more water.
•  The roots of small plants are embedded entirely in top soil.
•  The biological activity levels are highest.    

 

3. E  Horizon – This layer is called eluviations layer and is light in color.

• It is made up of mostly sand and silt.
• It is a mineral horizon, typically present in forested areas.

 

4. B Horizon – Also called the sub soil/ zone of accumulation.

•  It contains clay and mineral deposits.
•  Lesser amount of humus and more amount of minerals.
•  This layer is generally harder and more compact.
•  Less biological activity and heavier texture of soil.
•  Contain soluble minerals.

 

5. C Horizon  - Also called regolith

•  It consist of small lumps of rocks with cracks and crevices.
•  Plant root do not penetrate in to this layer.
•  Very little organic material is found in this layer.

 

6. R  Horizon – Also called bed rock layer that is beneath all the other layers.

• Made up of sedimentary or metamorphic rock.
• This layer is hard and difficult to dig.

 

 

            TYPES OF SOIL

 

Sr.no	Soil type	Nutrients amount	Hold water	Hold air	Colour
1	Sand	Poor	Poor	Good	Often light brown
2	Clay	Good	Good	Poor	Often mottled grey
3	Loam	Medium to Good	Good	Good	Brown to Black
4	Silt	Medium	Medium to Good	Medium to Poor	Brown to Black

 

• Loamy soil is best top soil for growing plant. It has right water holding capacity for the growth of plants.
• Clay and loam soil suitable for growing cereals like wheat and grain
• Cotton is grow in sandy and loamy soil.
• Lentils and other pulses grow in loamy soil.

                    

 

 

By - J.K.