ACTA AGRONOMICA VOLUME 40. (A MTA AGRÁRTUDOMÁNYI KÖZLEMÉNYEI, 1991)
1991 / 1-2. szám - SOIL SCIENCE AND AGROCHEMISTRY - I. BUZÁS-J. MEISEL-G. MÁDY-Z. SÁNDOR-B. LAKATOS: Preparation of native clay-humus complexes from soil by chemical extraction
.-li la Agronomien Hungarica, Vol. 40 ( I 2). />/». I -12 ( 1901 ) Soil Science and Agrochemistry PREPARATION OF NATIVE CLAY-HUMUS COMPLEXES FROM SOIL BY CHEMICAL EXTRACTION I. BUZAS*, .). MEISEL, G. MÁDY, Z. SÁNDOR and B. LAKATOS • RESEARCH INSTITUTE FOR SOIL SCIENCE AND AGR1CULTI HAL CHEMISTRY : CENTRAL RESEARCH INSTITUTE FOR CHEMISTKV OK THE HUNGARIAN ACADEMY" OF SCIENCES (Received: 3th June 1989; accepted: 13th October 1989) We used a (hi mol aqueous solution of tetrainethylammoniuin hydroxide (TMAH) at room temperature for the extraction of lulvic acid and humic acid-elav mineral complexes from different soils, and peats. By applying TMAH for the extraction could be obtained the humic substances in a nondegradative. native form and a nearlv quantitative amount. TMAH neither degrades nor even chemically modifies the humic substances. The fulvic acids were bound to an Amberlite XAD-8 resin. The humic substances were resolved with aqueous TMAH solution and reprecipitated with hydrochlorid acid, finally resolved with aqueous urea and TMAH solution and reprecipitated for further purification. The average molecular mass of humic substance was examined by gclehromatography and the structure of humic acid-elay mineral complexes by IK absorption spectroscopy. By this extraction method the humic acids can be obtained in their native form, i.e. in organominerals. in such a pure state that it becomes possible to examine the structure of these complexes by IR absorption spectroscopy. Studying the IR absorption spectra we can obtain a picture about the structure, i.e. bindings of the organomineral clay complexes to humic substances with metal ions which plays a very important role in the formation of soil structure. Keywords: clay-humus complexes, humic acid, fulvic acid, tetramethyl, ammonium hydroxide, IR-spectra Introduction The soil clay-humus complexes play au important role in forming the structure, and in the fertility of agricultural soil, as well as in providing plant nutrients (Stevenson, 1982; Theng, 1974, 1979). The analysis and physicochemical investigation of these clay-humus complexes are difficult, because during their extraction, these substances are irreversibly degraded to such an extent that it is not possible to prepare them "purely" in their natural state. The organic material of soils can primarily be divided into living and dead organic substances. The latter constitute the following groups: — new formations (primary and secondary metabolites of soil microbes). — non-humic substances (proteins, carbohydrates, waxes, etc.) — humic substances (the relatively stable and soil-characteristic decay materials of the soil macro- and microorganism and the plant residues of soil). Acta Agronomien Hungarica 40, 1991 Akadémiai Kiadó, Budapeti 1*