COMPARATIVE-STUDY OF SOIL HUMIC ACIDS USI NG FT-IR SPECTRA, THERMOGRAVIMETRY AND ACID-HYDROLYSIS

Humic acids, extracted from two soils, one under Medicago sativa and t he other uncultivated, were studied by FT-IR, thermogravimetry, acid h ydrolysis and gel filtration. Acid hydrolysis provides that functional groups as carbohydrate and peptidic are adsorbed to <<structural base >> and are released by acids. Other analytical methods used indicate t hat the HA formed under Medicago sativa has a chemical structure large ly composed of aliphatic groups, whereas that formed in uncultivated s oil has a chemical structure stable to hydrolysis and temperature.