POROSITY (% PORE SPACE)

Porosity ( % pore space )

Porocity is quality of being porous. In the soil, porosity determines storage capacity of the soil.

 It is defined as the ratio of  pore volume, to bulk volume and is reported either as a fraction or a percentage. OR

  Porosity refers to the percentage of the soil volume that is occupied by water and air. Arrangement of solid particles in the soil determines the total pores to a great extent.                           

Porocity or percentage space can be calculated as follow

        % solid space + %pore space = 100

        %pore space = 100 - % solid space 

       But %solid space = (bulk density/particles density) x 100 

Thus; %pore space = 100 - ( bulk density/particles density) x 

                                                                                                     100.

      GENERAL FACORS ON POROSITY

        1) Generally, sands soil have lower total space than 

                Clays and clayey soil.

        2) Present of organic matter in the soil increases the 

               porosity of the soil because it encoutages

              granulation

         3) A soil that is compact has less total pores space 

               than one that is loose.

        4) when the soil is planted with crops continuously 

             without the addition of organic matter also, the level

              of organic matter.