Types of Soil

The different types of soil are sand, silt, loam and clay. Soil texture is the relative proportion of these components in a given sample of soil. A soil which contains chiefly sandy soil. If a sample of soil  contains more than 25% of clay, it is said to be clayey. Between the two, there  is a type soil with plenty of sand and clay. Such s soil is called loam. A soil texture can also be referred to as light, medium or heavy depending on the combination of the different particles in the soil.

Soil particles

Soil particles are classified on the basis of their size groups and particles size diameter as follows:-

Types of soil particles  - particle size diameter                                                (mm)

Stones and gravel.        -      2.00 and above
Coarse sand.                 -       2.00. - 0.20
Fine sand.                      -        0.20 - 0.02
Silt.                                  -        0.02. -  0.002
Clay.                                -       0.002 and below


Sand- A sandy soil allows easy movement of water. It is therefore easy to work or cultivate. It is well drained and aerated, producing early crops but tends to suffer badly from drought and is poorly supplied with minerals needed by plant. Leaching of mineral salts goes  on at excessive rate. Addition of small amounts of humus can improve the condition of sandy soils.

Clay - Unlike sand, clay retains plenty of water  therefore remains water logged, badly drained and aerated. It is a heavy soil which is difficult to cultivate. Addition to humus can also improve the condition of clay soils.

Loam - soil containing a balanced mixture of large and small particles with adequate humus is classed as loam. Loam is therefore the best soil for agriculture.

     Apart from the different soil types already mentioned, the soil is further characterized by the presence of plant and animal remains at various stages of decay. These are referred to as humus. The humus gives the soil its characteristic dark colour and helps to improve soil fertility.

Soil structure

Soil structure is the name given to  the physical appearance of the soil depending on how individual soil particles or components are packed. Soil particles are usually arranged into aggregates or units owing to tgr mixing together of different soil types like sand and clay. The different units may be classified as very coarse , coarse, medium, fine and very fine.

  Soil structure has a direct effect on crop yield and when choosing a site for farming , the structure of the soil must be taken into consideration. For example , a good soil structure has the following characteristics:

(I) It must be well aerated I.e. good air circulation. This us generally an advantage to plants because water logging is prevented;

(ii) A good soil has adequate soil organic matter (humus) . The humus improves the stability of the soil and prevents the soil from bring broken up into clumps. A stable soil structure encourages good plant growth, because water and mineral components of the soil are retained.

   The structure or the stability of soil can be preserved by planting green cover crops or grass vegetation and by mulching ( covering with dead grass) or by the addition of certain chemicals such as lime.