MAINTENANCE OF IRON SUPPLY IN NUTRIENT SOLUTIONS BY A SINGLE ADDITION OF FERRIC POTASSIUM ETHYLENEDIAMINE TETRA-ACETATE

Abstract

When plants are grown in nutrient solution, invariably special attention must be paid to the problem of providing an adequate supply of available iron. Since iron is readily precipitated by high pH or phosphate, it is customary to add either organic or inorganic salts of iron to the nutrient solution at frequent intervals. HORNER, BURK, and HOOVER (1) developed a synthetic humate capable of hiolding iron in solution at moderately high pH and phosphate concentrations. Unfortunately, the humate is difficult to prepare and of indeterminate composition. EDGERTON (2) showed that by substituting metaphosphate for the usual orthophosphate in the nutrient solution, the resulting iron metaphosphate complex did not precipitate and was a satisfactory source of iron for plants. However, it may not always be desirable to use the meta instead of the orthophosphate and miietaphosphoric acid as generally available contains large amounts of sodium.