BORON ADSORPTION AND DESORPTION BY SOME HAWAIIAN SOILS

Abstract

B adsorption by Low Humic Latosols of Hawaii was studied by equilibrating soils with boric acid solutions of known concentrations (0-5-ppm B). B was adsorbed by the soils in a manner conforming to the Langmuir equation. Adsorption capacities of soils calculated from the equation were related to soil pH. B adsorption increased as pH values of soils were increased. Desorption of adsorbed B showed that B adsorption by soils was not readily reversible. This would indicate that B probably formed more than one type of reaction products in the adsorption process. B extraction or desorption from soils was found to be influenced by the length of heating of soil suspensions, soil-water ratios, and the number of extractions. Longer periods of heating, wider soil-water ratios, and greater number of extractions all tended to increase the recovery of native or added B from soils. The relationship between B adsorption-desorption and B availability was briefly discussed.