3.4 Effect of trees on soil
Trees improve the physical and fertility conditions of the soil. The extent
of this improvement is dependent upon the type of tree and various other
factors. In general, in the arid and semi-arid lands, the soil fertility
improvement is a slow process. Under P. cineraria plantation, silt and clay
content of soil increased up to a depth of 120 cm, whereas in the open field
devoid of trees, changes in soil physical conditions were confined only to
90 cm [27]. Such improvements in the soil physical conditions resulted in
the maintenance of higher soil moisture beneath this tree [2, 12]