Mobilization of X‐ray amorphous and crystalline aluminum and iron phosphates by common soil extraction procedures

Abstract

Soil extraction with 0.1 M NaOH completely dissolves X-ray amorphous as well as crystalline AlPO4 and FePO4. Extraction with acidic NH4 oxalate completely mobilizes X-ray amorphous AlPO4 and FePO4 in addition to phosphate adsorbed to poorly-crystallized Al and Fe minerals, but only a minor portion of crystalline AlPO4 and FePO4. Extraction with dithionite-citrate-bicarbonate mobilizes X-ray amorphous AlPO4 and FePO4 as well as crystalline FePO4, but only a minor portion of crystalline AlPO4.