Comparison of an oxalate-extraction methon and an infrared spectroscopic method for determining allophane in soll clays

The day fractions of nine New Zealand soils and an andesitic pumice, separated using minimal prctreatment, were examined by infrared spectroscopy (IR) and by dissolution in acid oxalate and pyrophosphate reapnts. Allophane, with an Al/Si ratio dose to 2/1, was prcsent in most samples and was estimated quantitatively for acid-oxalate extraction of Si and from the IR absorbance at 348 cm−1. These two methods pvc quantitative results wbich were in good agreement not only for clays formed from volcanic ash but also for clays lormed from basalt and clays formcd in podzolizcd soils. The hipt allopbane contents in the soil clays occurred in the cJays from the Mairoa Ash soil and from the Addison and One Tree Point podzolized soils.