Soils

Soils

1. Soil components

   • Soild phase
     • As a result of weathering activities soils are made up of a number of different particles. Soils particles are classified according to size, which is based on particle diameter
   • Liquid phase
     • The soil solution contains many elements dissolved in water, resulting in the soil either being acidic or alkaline. The variable composition of the soil causes changes in the soil acidity or alkalinity and the mineral availability.
       • The main sources of minerals in the soil is the soil solution, the primary minerals released through weathering and the exchangeable ions from clay and organic matter
   • Gas phase

2. Physical properties of soil

   • Parent material
     • Parents material is the storehouse of future soil material and soils can be classified into one of two groups according to the source of their parent material.
       • Transported
       • Sedentary
   • Soil colour
     • Soils are often referred to by their colour as this is often the initial observation made about a soil. It is useful feature for the description and identification of a soil.
   • Soil texture
     • Soil texture refers to the size of soil particles in a soil, and allows differentitstion
       • Mechanical Analysis
         • This involves the dispersion of soil particles by violent agitation of a soil sample with a mixtureof water and dispersal agent such as Calgon or hydrogen peroxide
       • Texture triangle
   • Soil structure
     • Soil structure refers to the arrangement of soil particles (sand, slit and clay) in a soil. The basic unit of structure is called a soil ped and forms a natural soil aggregate.
       • The structure will influence the aeration, water penetration, heat transfer, rates of gaseous exchange, mechanical strength and erosion potential of a soil
   • Soil consistence
     • Soil consistence is a measure of the mechanical strength of a soil, based on the force necessary to break a block of soil

3. soil chemistry

   • pH
   • Salinity

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