Introduction of Soil and its Characteristics

Soil 

Soil is a natural body of mineral and organic constituents differentiated into horizons usually unconsolidated, of variable depth which differs among themselves as well as from the underlying parent material in morphology, physical makeup, chemical properties and composition and biological characteristics.

 Soil profile- 

The vertical section of the soil showing the various layers from the surface to the unaffected parent material is known as soil profile. The various layers are known as horizons.

- There are 5 master horizons in the soil profile Not all soil profiles contain all 5 horizons and So, soil profiles differ from one location to another.

-  The 5 masters horizons are represented by the letters : O, A, E, B and C.

-  O : The O horizon is a surface horizon that is comprised of organic material at various stage of decomposition. It is the most prominent in forested areas where there is the accumulation of debris fallen from trees.

-  A : The A horizon is a surface horizon that largely consist of minerals (sand, silt and clay) and with appreciable amounts of organic matter. This horizon is predominantly the surface layer of many soil is grassland and agricultural, lands.

-  E : The horizon is sub surface horizon that has been heavily leached. Leaching is the process in which soluble nutrients are lost from the soil due to precipitation or irrigation. The horizon is typically light in color. It is generally found beneath the O horizon.

-  B : B horizon is a sub surface horizon that accumulated from the layers (s) above. It is a site of deposition of certain minerals that have leached from the layers (s) above.

-   C : The C horizon is a sub surface horizon. It is a least weathered horizon. Also known as the saprolite, it is consolidated, loose parent material.

-  R  : Un weathered  rock & exists below the parent material.

Soil texture- 

     refers to the relative proportion of particles or it is the relative percentage weight of the three soil separates viz, sand, silt and clay or simply refers to the size of soil particles.

Loam – A type of soil texture with water holding capacity and drainage suitable for cultivation of variety of crops.

Soil structure- 

The arrangement and organization of primary and secondary particles in a soil mass is known as soil structure.

Saline soils-

-  Saline soils are characterized by higher amount of water soluble salts due to which the crop growth is affected.

Sodic soils-

- Sodic soils are characterized by the predominance of sodium in the complex with exchangeable sodium percentage exceeding 15 percent and the pH more the an 8.5.

Acid soils-

-  Acid soils are characteristically low in pH ( <6.0) Predominance of H + and A13+ cause acidity resulting in deficiency of P, K, Ca, Mg, Mo and B.

Sandy soils-

-  Sandy soils are containing predominant amounts of sand resulting in higher percolation rates and nutrients loss.

-  Alkaline soil- A soil with pH above 7, usually above 8.5 are considered alkaline. Alkaline soil often occurs in acid regions that receive less than 25 inches of rain per year.

-   Cal carious soil- Soil with kankar nodules in the plough zone and subsoil.

 Alfi soil- 

    Soil with grey to known surface horizons mediums to high supply of bases and B horizons of alluvial clay accumulation or savanee - vegetation in climates with slight to pronounced seasonal moisture defect.

Arid soil- 

Minerals soils that have an aridic moisture regime. These are desert soil.