COMPARISON OF A HOT WATER AND COLD 0.01-M CACL2 EXTRACTION PROCEDURES FOR THE DETERMINATION OF BORON IN SOIL

In 100 different soils, hot (100C) water extractable boron was determined and the results were compared with boron data after extraction of the same soil samples with cold (20C) 0.01 M CaCl2. Since the boron concentrations in cold soil extracts are too low for direct determination, the extracted boron was converted into BF4- and subsequently extracted with a liquid anion exchanger, Aliquat 336, into xylene, and measured by ICP-AES. A linear relation with R2 = 0.74 was found between the two tested procedures. It is, therefore, concluded that with a cold 0.01 M CaCl2 extraction equally valuable soil boron values can be obtained as with the more difficult to standardize hot water extraction procedure.