Influence of Liming and Mineral Fertilization on Plant Uptake of Radiostrontium from Danish Soils

The uptake of radioactive strontium by rye grass and red clover was studied in pot experiments, using 20 typical Danish agricultural soils. Comparisons were made between the effects of adding Ca in the form of carbonate, sulfate, and chloride, and the respective Mg compounds on Sr uptake by plants grown on three different soils. The influence of nitrogen and potassium application on uptake of Sr/sup 90/ by oats was studied for two different soils. The results showed conclusively that in red clover the uptake of radioactive strontium was much greater than in rye grass. The uptake from the different soils decreased with increasing axnounts of exchangeable Ca. Adding CaCO/sub 3/ at 2.5 tons/ha showed little effect on Sr uptake. However, heavy amounts of CaCO/ sub 3/, at 5 and 10 tons/ha, reduced Sr/sup 89/ concentration of the plants by 15 to 30 per cent, depending on the type of soil. CaSO/sub 4/ application showed little effect, and CaCl/sub 2/ increased Sr/sup 89/ concentration of plants. The Sr/sup 89//Ca ratio in plants could be reduced by the three different Ca compounds, the reduction being most effective when the carbonate was used. Mg as carbonate or sulfate proved more effective in reducing Sr/sup 90/ concentration than did the corresponding Ca compounds. An increase in S/sup 89/ concertration of plants followed the application of MgCl/sub 2/. Nitrogen fertilization increased yield and Sr/sup 90/ concentration of straw, but lowered Sr/sup 90/ concentration in grain. The concentration of Sr/sup 90/ and Ca decreased with increasing amounts of added K, leaving the Sr/sup 90//Ca ratio of the crops unaffected.