Molecular weight distribution of soluble organics from laboratory-manipulated surface soils

• Published in: Soil Science Society of America journal Vol. 56; no. 4; pp. 1305 - 1310
• Main Authors: Homann, P.S. (Oregon State Univ., Corvallis, OR), Grigal, D.F
• Format: Journal Article
• Language: English
• Published: Madison, WI Soil Science Society of America 01-07-1992; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; AIR; AIRE; AMENDEMENT DU SOL; ANEGAMIENTO; Biological and medical sciences; CALENTAMIENTO; CARACT MORFOLOGICAS DEL SUELO; CENDRE; CENIZA; CHAUFFAGE; Chemical, physicochemical, biochemical and biological properties; ENGORGEMENT DU SOL; ENMIENDAS DEL SUELO; Forests; Fundamental and applied biological sciences. Psychology; MATERIA ORGANICA; MATIERE ORGANIQUE; MINNESOTA; Organic matter; PESO MOLECULAR; Physics, chemistry, biochemistry and biology of agricultural and forest soils; POIDS MOLECULAIRE; SECADO; SECHAGE; Soil science; Soil surfaces; Soils; SOL; SOL DE FORET; SOLUBILIDAD; SOLUBILITE; SOLUCIONES DEL SUELO; SOLUTION DU SOL; SUELO; SUELO FORESTAL; TRAIT MORPHOLOGIQUE DU SOL; UREA; UREE; Waterlogging; Organic carbon; Urea; Organic matter; Treatment; Ash; Transfer; Forest soil; Perturbation; Solubilization; Soil profile; Soil solution
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1992.03615995005600040049x

Transfer of organic matter from solid to solution phase is the first step in the redistribution by leaching of organic C and associated elements in forest soil profiles. To examine the effects of disturbances on solubilization of organics, three A horizons and one O horizon were exposed to air drying, waterlogging, addition of urea, addition of ash, and addition of ash in combination with heating at 250 degrees C. Following incubation at 20 to 22 degrees C for 1 to 50 d, soluble organic C (SOC) was extracted with 0.5 mM SrCl2. The SOC was 0.2 to 0.7% of total organic C in controls. Urea and heat-plus-ash treatments yield up to 17 times more SOC than controls, and other treatments yielded up to three times more than controls. Distribution of SOC among molecular-weight classes, as determined by dialysis, was 21 to 32% in the 3500-dalton class, 8 to 20% in the 3500 to 14000-dalton class, and 47 to 71% in the 14000-dalton class. Urea treatment yielded a higher proportion of SOC in the 14000-dalton class than in the controls, while air drying resulted in a lower proportion. Both the quantity and quality of soluble organics can be influenced by sod disturbances, but the specific response varies with the type of disturbance