Sr90 CONCENTRATION IN DEEP- AND SHALLOW-ROOTING SPECIES AS AFFECTED BY PLACEMENT OF Sr90 AND FERTILIZER TN THE SOIL

Abstract

In greenhouse experiments involving the placement of Sr90 and fertilizer in the soil, marked reductions in Sr90 concentration were found for timothy and wheat when the Sr90 was placed deep in the soil compared with the results found for shallow placement. Fertilization of the soil above the zone of Sr90 contamination led to further decreases in Sr90 concentration in timothy and wheat.Results for alfalfa differed from the results for timothy and wheat. A combination of shallow fertilization and shallow placement of Sr90 caused the highest concentration of Sr90 in plants. Deep placement of Sr90 did not reduce the Sr90 concentration in the first cutting of alfalfa, but as the plant matured, there was a reduction caused by deep placement of Sr90. Deep placement of Sr90 combined with deep placement of fertilizer caused an increase in the Sr90 concentrations in alfalfa compared with deep placement of Sr90 alone. The greatest reductions in Sr90 in the plants were found where the deep placement of Sr90 was combined with shallow placement of the fertilizer. Surface or subsurface watering of the crop did not affect the main conclusions with regard to placement of Sr90 and fertilizer.