(6) Permeability

                     Soil permeability is the ease with which air, water, or plant roots penetrate or pass through the soil. The size of pore space and interconnectivity of the

spaces help determine permeability, so the shape and arrangement of grains play a role.

                Permeability for soils
Type of grain                                          Permeability(cm/s)

Well sorted gravel                                 102 to 1
silt sands, fine sands                             10-5 to 10-3
silt, sandy silts, clayey sands, till         10-6 to 10-4
Clay                                                          10-9 to 10-6

Although sandy soils have lower porosity than clay soils, sandy soils have relatively larger permeability than clay because pores in clay are not connected together very well.

The most rapid water and air movement is in sands because sand soils have relatively larger pores and loose aggregated structure.