In the past, soil management has consisted primarily of clean cultivation to control weeds. The advantages of this approach include the avoidance of herbicides and forcing roots to go deeper. The disadvantages of this approach are increasingly recognized, however. Over time, clean cultivation leads to a deterioration in soil structure and also to a decline in soil biota, particularly earthworms. Modern soil management seeks to conserve and, if necessary, increase the organic matter content; to conserve and improve soil structure and porosity, and thereby improve aeration and free absorption and drainage of soil water and resistance to soil erosion; and to maintain a reserve of nutrients in organic and slowly available inorganic forms to provide a steady and balanced supply of soil nutrients matched to the plants’ needs.