Previously, it was thought that the absorption of mineral salts from the soil took place along with the absorption of water, but it is now well established that the mineral salt absorp­tion and water absorption are two different processes. Mineral salts are absorbed from the soil solution in the form of ions. They are chiefly absorbed through the meristematic regions of the roots near the tips.

However, some mineral salts may also be absorbed in other locations on the root surface or over the entire root surface including the zone of elongation and root hairs that depends upon the high availability of such minerals around them and/or strong tissue demand at such locations.

The plasma membrane of the root cells is not permeable to all the ions. It is selectively per­meable. All the ions of the same salt are not absorbed in an equal rate but there is unequal ab­sorption of ions. The first step in the absorption of mineral salts is the process of Ion-Exchange which does not require metabolical energy but greatly facilitates mineral salt absorption.