Permeability

• Clay soils have only tiny (microscopic) pores. These pores are the holes between soil particles. Since they are small, the flow of water and other liquids and gases (air, carbon dioxide, hydrogen sulphide etc) is slow and these soils are generally of low permeability or are even impermeable - water cannot penetrate at times.
• Gravels and sands have larger gaps because they are larger pieces of soil and so don't pack together as tightly as clays and silts can. As a result, gravels and sands allow more rapid flow and are generally considered highly permeable. This means that they drain freely, lose water freely and that plants growing in them are more susceptible to drought conditions and less susceptible to waterlogging.
• In between these two extremes are soils that have a mix of clay, sand, silt and possibly gravel. Their texture is the result of the specific mix of particles and this determines their permeability.

• better soil structure
• more organic matter
• greater biological activity and through using tools and techniques such as:
  • Grazing shock and
  • Green manures
  • Return a third to the soil
  • Non-inversion tillage
  • Litter
  • Ground cover