The movement of copper, molybdenum, and selenium in soils as indicated by radioactive isotopes

Abstract

Radioactive isotopes of copper, molybdenum, and selenium have been applied to a number of soils in order to study the movement of these trace elements under the influence of various fertilizer treatments. With soils of moderate exchange capacity the copper remained near the surface following all fertilizer treatments and the equivalent of several years' rainfall. With light soils of low exchange capacity some penetration of copper occurred, especially following superphosphate and an aqueous extract of lucerne.

With molybdenum in general a high proportion of this element was leached right through the soils, except in the case of the two laterite soils examined, where up to half of the molybdenum was retained near the surface.

Selenium applied as sodium selenite was intermediate between the extremes illustrated by copper and molybdenum, in that a high proportion was retained by the calcareous soils but not necessarily at the surface. The lighter soils retained a much lower proportion of selenium.