Specific Character of Boron Adsorption by an Amorphous Soil

The adsorption of boron by an allophanic soil as influenced by the presence of sulfate, phosphate, and monosilicic acid was studied at pH 6.0 and 8.5. Amounts of B adsorbed by the soil from a 4.8 m M B solution which contained sulfate or phosphate ions in varying concentrations up to 0.1 M were independent of the presence of these anions. Pretreatment of soil by repeated saturation with 1.42 m M Si solution resulted in a slight but progressive decrease in the quantity of B adsorbed subsequently from the 4.8 m M B solution. Apparently, B adsorption by allophanic soils is more or less specific, being essentially independent of the presence of other anions.