Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2003
Publication Date: November 6, 2003
Citation: GONZALEZ, J.M., LAIRD, D.A. SMECTITE AND GOETHITE CATALYZED CONDENSATION OF ARGININE AND GLUCOSE. ASA-CSSA-SSSA ANNUAL MEETING ABSTRACTS. 2003. CD-ROM. MADISON, WI.
The Maillard reaction, condensation of amino acids and reducing sugars, is an alternative theory of humic substances formation that has not been widely studied under conditions normally found in soils. The general objectives of this study were to determine whether smectites and goethites catalyze the abiotic polymerization of arginine and glucose to form humic-like compounds. The effects of smectite type, saturating cation, and the degree of Al-substitution in goethites on the polymerization reaction were also studied. Four cation-saturated smectites and four Al-substituted goethites were abiotically incubated with solutions containing a mixture of arginine + glucose for 21 days at 37EC. After the incubations, total C recovered ranged from 80.6 to 123.8% and from 100.5 to 105.1% for the clay and goethites systems, respectively. At the end of the incubations, 21.4 to 50.3% of the added C and 16.5 to 90% of the added N was sorbed on the various smectites in a form that could not be desorbed by washing with 100 mM CaCl2. X-ray diffraction analysis indicated that some of the sorbed C was intercalated in the smectites and FT-IR analysis provided evidence of new absorption bands at 1650 and 1668 cm-1, which are consistent with Maillard reaction products. Thus, the results indicated that smectites catalyze the condensation of arginine and glucose to form humic-like products, whereas goethites are less effective than smectites for catalyzing these reactions.