The movement of water through a column of soil is called percolation. It is important for two reasons. i) This is the only source of recharge of ground water which can be used through wells for irrigation ii) Percolating waters carry plant nutrients down and often out of reach of plant roots (leaching)  In dry region it is negligible and under high rainfall it is high  Sandy soils have greater percolation than clayey soil  Vegetation and high water table reduce the percolation loss