The uptake of strontium and calcium from soils by grasses and legumes and the possible significance in relation to SR-90 fallout

Abstract

In view of the nature of much of the evidence on which future world-wide radioactivity levels have been predicted, and also the possibility of increased bomb testing, reactor accidents, or even atomic warfare, it seemed desirable to determine if species differences existed in forage plants, such that some might take up less strontium from the soil than others. Sixteen species and strains of forage legumes and grasses were grown on three different soils, similar in texture and pH but varying in strontium and calcium content. The plant tops and the soils were analyzed for strontium and calcium. A method was developed, using X-ray emission spectrography, for the analysis of strontium. The results indicate three significant features: 1) Every legume species rakes up more strontium than any grass; 2) within either the grasses or the legumes the variation in strontium content between species and varieties is not marked; and 3) the amount of stronrium taken up is directly related to the calcium taken up. A grass diet for dairy cows has an advantage over a legume diet in that both strontium and calcium levels are lower, and a higher calcium supplement can be added to the grass diet to greatly decrease the Sr/Ca ratio before calcium toxicity results. It seems reasonable that the strontium (or Sr-90) content of milk can be reduced by a factor of about 8 when cows are fed grass supplemented with calcium.