The movement of cobalt and zinc in soils as indicated by radioactive isotopes

Abstract

A method has been developed whereby labelled cobalt and zinc were applied to the surface of columns of soil in order to study the movement of these cations under the influence of rainfall and various fertilizer treatments. The results of the investigation demonstrate that in soils of moderate exchange capacity, whether this is provided by clay or by organic matter, the cobalt and zinc remain close to the surface of the soil even after the application of water equivalent to several years' rainfall and dressings of copper sulphate, superphosphate, aqueous extract of lucerne, and water saturated with carbon dioxide. With very light soils of low exchange capacity a year's rainfall alone did not leach the cobalt or zinc downwards, but rainfall which followed treatments with the same dressings induced a considerable downward movement of both cobalt and zinc.