FRACTIONATION OF ORGANIC-MATTER AND ANALY SIS OF HUMIC COMPOUNDS FROMHUMIFEROUS CALCIUM-MAGNESIUM SOILS IN THE FRENCH JURA

This Paper studies the organic matter of calcimagnesic soils of the Ju ra (humocalcic soils and brown calcic soils) which are widely represen ted in the alpine mountainous system. After fractionation, their organ ic matter was divided into two parts: humic substances (70%) and poorl y transformed plant residues. In the soil, the humic compounds were fl occulated by calcium which was included in the intermolecular bondings . The iron of the oxydes was also involved in the organo-argillic bond ing because the complete extraction of the humic compounds was possibl e only after removing the iron. According to the analytic data, IR spe ctra and acid hydrolysis, the humic acids studied have more peptidic a nd osidic side-chains and more quinonic bindings than other known humi c acids. Such structures result from an intense oxidative humification and rapid polycondensation of various molecules of microbial and rhiz ospheric origin. Involved in organo-mineral complexes and water stable aggregates, they entrap numerous plant residues.