Soil porosity

                          Soil porosity is the total amount of pore spaces that are not occupied by solid particles. The shape and arrangement of soil particles help determine porosity. Sand has a relatively lower porosity than silt and clay.

Porosity Ranges for soil particles 

Type of soil              Porosity%

well sorted                          sand or gravel

            25-50

Sand mixed with gravel

        20-35

Silt                                35-50

Clay                               33-60

                   Although clay particles have smaller pores than sands clay have relatively larger soil particles.

                  Therefore the diameter size of the grain does not affect the porosity

                   Because sandy soils are not well aggregated together so sandy soils have relatively less amount of lager size pores. Therefore sandy soils have relatively lower porosity. Clay soils are well aggregated together by binding agents and also have macrospores between aggregates and microspores within aggregates. Therefore clay soils have relatively larger porosity.