environmental geology ?

[lina0883]

why are only positively charged ions absorbed in significant amounts by soils?

[gilles_33]

The positively charged ions are called 'cations' which include potassium(K+), Calcium(Ca++), magnesium(Mg++), iron(Fe+++), zinc(Zn++), and so on. The negatively charged ions are called anions and the important plant nutrients taken in this form include nitrogen(NO-3), phosphorous( H2PO-4), sulphur(SO-4), Chlorine(Cl), etc.

The process of nutrient uptake by plants refers to the transfer of the nutrient ions across the soil root interfaces into the plant cell. The energy for the process is provided by the metabolic activity of the plant and in its absence no absorption of nutrients take place. Nutrient absorption involves the phenomenon of ion exchange. The root surface, like soil, carries a negative charge and exhibits cation-exchange property. The most efficient absorption of the plant nutrients takes place on the younger tissues of the roots, capable of growth and elongation.