The Uptake of Calcium and Strontium by Plants from Soils and Nutrient Solutions

Abstract

Plants have been grown in soils and nutrient solutions containing different Ca/Sr ratios to find out whether there is any biological discrimination between calcium and strontium. When tomato plants are grown in nutrient solutions containing molar Ca/Sr ratios from 2/1 to 4,000/1, the shoots do not distinguish between the elements, but the roots absorb strontium preferentially at low concentrations of this element. Since ion exchange resins show the same phenomenon, though to a less marked extent, this is believed to be a physico-chemical rather than a biological effect. No chemical reagent has been found which can extract calcium and strontium from soils in the same ratio as plants. Ammonium acetate extraction may give misleading results for the plant-available Ca/Sr ratios in the soil. Data for the Ca/Sr ratios in barley and lucerne grown on soils containing ratios from 3/1 to 650/1 emphasize this point.