APPLICATION OF CENTRIFUGING STUDIES IN SOIL SOLUTIONS

A simple apparatus to extract soil solution by centrifuging from specific horizons has been devised and used to study the slow transfer of copper (Cu) and cadmium (Cd) within the soil when lysimetry is not possible or inefficient. It has been tested on the several horizons of two sandy soils fairly free of pollution, a Typic Dystrochrept and a Typic Haplorthod. With the same centrifugal speed, it extracted solution at suctions that depend on the horizons' characteristics. It produced solution free of contamination and enabled small concentrations of heavy metals to be measured. Concentrations of Cu and Cd in the capillary water extracted are generally greater than the solutions collected by lysimetry and their evolution with time is also different. These solutions give an instantaneous view of the heavy metal concentration in the capillary fraction of the soil solution just after a rain.