THE DETERMINATION OF HOT-WATER-SOLUBLE BORON IN SOME ACID OREGON SOILS USING A MODIFIED AZOMETHINE-H PROCEDURE

A method is proposed for determination of hot-water-soluble B in acid soils from western Oregon. The soil sample is boiled in 0.02 M CaCl2, filtered, and B-determined using azomethine H. Soils extracted in this way yielded extracts with little color and the predicted error due to this color was 0.00-0.07 ppm B. The use of charcoal as a decolorizing agent resulted in comparatively high predicted errors. Inductively-coupled plasma emission spectroscopic (ICP) analysis of distilled water and 0.02 M CaCl2 extracts indicated that the extractable B level was not affected by the presence of CaCl2. Azomethine H yielded comparable values to ICP but the curcumin method gave high values for hot-water-soluble B.