Soil Humic Substances

Abstract

Introduction Genesis The Lignin‐Protein Theory The Sugar‐Amine Theory The Polyphenol Theory Extraction, Fractionation and Purification Extraction Methods Fractionation Procedures Purification Procedures Sequential Extraction/Fractionation Procedures Comprehensive Isolation Procedure Proposed by the IHSS Chemical Composition, Properties and Structure Elemental Composition Functional Groups Charge Characteristics and Cation Exchange Capacity Molecular Weight, Size and Shape Structural Components Molecular Models Fractal Nature Soil Fertility Functions Physical Functions Chemical Functions Nutritional Aspects Biological Actions Environmental Functions Interactions with Organic Pollutants Interactions with Trace Metals Summary and Concluding Remarks

Recent applications of vibrational mid-Infrared (IR) spectroscopy for studying soil components: a review

“…Results obtained by IR spectra have shown that carboxyl groups are the most important functional groups in HS, accounting for the majority of their charge, acidity, and metal and particle surface binding characteristics (Senesi and Loffedro, 2001;Stevenson, 1994). In HA spectra the carboxylate bands appear at 1624-1633 cm -1 and 1385-1383 cm -1 , respectively, depending on pH.…”

“…R-COOH and R-OH (Lumsdon and Fraser, 2005). On a mass basis, HA is less charged than FA, but HA shows more poliaromatic structure (Lumsdon and Fraser, 2005;Senesi and Loffedro, 2001). Some studies applied the FTIR spectroscopy to characterize functional groups (D'Orazio and Senesi, 2009;Francioso, et al, 2002) and biological properties of different HA molecular weight fractions.…”

“…Humic substances (HS) are natural organic components which are widely distributed in soils, river sediments and brown coals (Senesi and Loffedro, 2001;Stevenson, 1994). The variety of chemical and biological reactions involved in their genesis make HS very complex.…”

Structural Features of Humic Acid of the Coastal Sediment in Ariake Sea Tidelands: Use of Humic Acid as an Environmental Indicator for River Basins and Coastal Regions

“…Humic compounds are produced primarily by abiotic reactions of relatively small molecules, such as lignins, lipids, and carbohydrates from plant and microbial biopolymers involving direct conversion; these abiotic reactions are then followed by degradation. 2 The Ariake Sea, which is a typical semi-closed bay located at Kyushu Island in Japan, has a maximum tidal range of about 6 m during the spring tide, and has a vast tideland area covered with several living organisms that are unique in Japan. 3 The unique living systems of this area are likely to be influenced by the circulation of organic and biological compounds from a combination of marine algae and other marine microorganisms that are produced and metabolized.…”

Soil and compost humic fractions regulate the response of Sclerotinia sclerotiorum to exogenously added allelochemical compounds

“…Loffredo et al (2005) found that the allelopathic effects of SA, FA and CA on the early growth of tomato and lettuce disappeared with the addition of different humic or fulvic acids in their growing medium. HA fractions may interact with such monomeric compounds and act as a reaction partner and/or as a protecting ligand (Senesi and Loffredo 2001). The different responses of the fungus to the different allelopathic agents could be attributed to fungal enzymatic adaptation to the various available C sources (Souto et al 2000).…”