Chemical and mineralogical changes in the fine and course fraction of volcanic soil as a function of root depth

We have studied the influence of the broom roots on the chemical and minera logical characteristics of fine earth and skeleton from volcanic soils. Her e, the presence of a yellowish collar all around the roots of the plant all owed to sample three soil material from each horizon: matrix, outer rhizosp here and inner rhizosphere. Acidity, organic C and total N increases from t he matrix towards the inner rhizosphere for the fine earth; for the skeleto n, acidity and organic C follow this trend, total N shows an opposite tende ncy. The activity of the roots favors the alteration of the hematite. The y ellowish color of the rhizospheric material is considered due to the dissol ution of hematite with the consequent formation of lepidocrocite. These res ults highlight on the mistakes that is possible to commit if one only consi ders soil vertical variations. We also concluded that in the future, the pl ant-skeleton relationships must be studied mon in depth.