INTRODUCTION TO SOIL CHEMISTRY.

SOIL CHEMISTRY

 Soil is the upper layer of the earth's crust on which pants and animals are live. The activities of plant and animal affect the soil properties.
                                           

COMPENENTS OF THE SOIL.

   The soil consist of minerals, organic materials and organisms which together form the solid particles of the soil, Also soil contain a very small pores called POREAPACES, porespaces filled with air and mostures. There fore soil consist of the following component;

            1) inorganic or mineral particles 

            2) organic matter 

            3) living organisms

            4) water 

            5) air.

All the component above mixed to form soil, during mixing chemical reactions take place and are these reactions which give suitable environment for plants to grow up.

1. Iorganic particles (mineral particles) 

        Minerals or inorganic particles in the soil are obtained through weathering process of parent rock. These particles form about 45% of the soil. 

  The size of inorganic particles of the soil has big effect on soil poreties especially in soil texture. 

       The inorganic particles with small size they have large surface area in which physical and chemical reaction can take place. Also the size of individual pores depend to some extent on size of inorganic particles, the small the size of particles the small size of pores.

2. Organic matter.

      The source of organic matter in the soil are dead plants and animals. Organic form about 5% of the mineral soil.

   Organic matter of the soil consist of two compents which are;

         1) animals and plants remain which are not yet been completely broken down

         2) animals and plants which are already been broken down.

Remaining parts of plants and animals are decomposed by micro organisms and humus are formed.

   Humus consist of very small prticles which are usually black or brown in color. Humus contain mineral salts, humus there fore source of mineral salts which used by plant, humus also good binding agent for soil particles, it is act as glue fore soil particles so that they are joined tigether.

  

        When soil particles are joined together soil structure is formed and soil structure is very important because determine the amount of air and water which soil can hold as well as movement of air in the soil.

3. Living organisms.

      The soil contains plants and animals, member of plant kingdom are called Flora and those of animals kingdom called fauna.

 These organisms have very important influence in chemical reactions of soil. Organisms such as earth work worms, bacteria as well as fungi feed on the plants remains and animals remains and through their feeding remains are broken down and nutrients element are released to the soil. This process is called MINERALIZATION.

4. Soil water.

        Most of water in the soil are coming from rain. In the soil there are pores, these pores are of two category which are; 

                                          1) .microspores

                                          2) .macrospores

Water in the soil occupies microspore while macrospores occupied by air. When the water in the soil becomes smaller, it held more tightly in the pore space there fore plants growing in the soil find it more difficult to absorb water from the soil.

    Water dissolves mineral salts in the soil. This mixture of water and mineral salts is called the soil solution, supplies mineral nutrients to the plants growing in the soil.

4. Soil air.

         Also soil contain air in the spores especially in macro spores. Plants roots and soil organisms need air to respire, without air plants roots and soil organisms will not be able to respire and there fore die.