Properties of soil humic substances in fractions obtained by sequential extraction with pyrophosphate solutions at different pHs

References

• Cameron , R.S. , Thornton , B.K. , Swift , R.S. and Posner , A.M. 1972 . Molecular weight and shape of humic acid from sedimentation and diffusion measurements on fractionated extracts . J. Soil Sci. , 23 : 394–408 – 394–408 .
   Web of Science ®Google Scholar
• Chitani , K. and Kondo , Y. 1958 . “ Kansyoeki ” . In Jikken Kagaku Koza , Edited by: Akahori , S. and Funahashi , S. Vol. 24 , 201–229 – 201–229 . Tokyo : Maruzen .
   Google Scholar
• Choudhri , M.B. and Stevenson , F.J. 1957 . Chemical and physicochemical properties of soil humic colloids: III. Extraction of organic matter from soils . Soil Sci. Soc. Am. Proc. , 21 : 508–513 – 508–513 .
   Google Scholar
• Clapp , C.E. and Hayes , M.H.B. 1996 . “ Isolation of humic substances from an agricultural soil using a sequential and exhaustive extraction process ” . In Humic Substances and Organic Matter in Soil and Water Environments: Characterization, Transformations and Interactions , Edited by: Clapp , C.E. , Hayes , M.H.B. , Senesi , N. and Griffith , M. 3–11 – 3–11 . St. Paul : International Humic Substances Society, Inc., Univ. Minnesota .
   Google Scholar
• Gascho , G.J. and Stevenson , F.J. 1968 . An improved method for extracting organic matter from soil . Soil Sci. Soc. Am. Proc. , 32 : 117–119 – 117–119 .
   Web of Science ®Google Scholar
• Hayes , M.H.B. 1985 . “ Extraction of humic substances from soil ” . In Humic Substances in Soil, Sediment and Water , Edited by: Aiken , G.R. , McKnight , D. , Wershawet , R.L. and MacCarthy , P. 329–362 – 329–362 . New York : John Wiley & Sons, Inc. .
   Google Scholar
• Hayes , M.H.B. , Swift , R.S. , Wardle , R.E. and Brown , J.K. 1975 . Humic materials from an organic soil: A comparison of extractants and of properties of extracts . Geoderma , 13 : 231–245 – 231–245 .
   Web of Science ®Google Scholar
• Honda , C. 1983 . Characterization of the composition of humus among soils . Bull Natl. Inst. Agric. Sci. , B35 : 111–198 – 111–198 . (in Japanese with English summary)
   Google Scholar
• Honda , C. 1984 . A proposal of a new method for characterizing humus composition among soils: 1. In situ fractions of soil humus . Pedologist , 28 : 26–36 – 26–36 . (in Japanese with English summary)
   Google Scholar
• Kawahigashi , M. , Fujitake , N. , Azuma , J. and Takahashi , T. 1995 . Preparation of humic acid fractions with a definite range of particle sizes by gel permeation chromatography (GPC) . Soil Sci. Plant Nutr. , 41 : 147–150 – 147–150 .
   Web of Science ®Google Scholar
• Oba , H. 1964 . Kobo-Oba\s's method . Pedologist , 8 : 108–116 – 108–116 .
   Google Scholar
• Piccolo , A. and Mirabella , A. 1987 . Molecular weight distribution of peat humic substances extracted with different inorganic and organic solutions . Sci. Total Environ. , 62 : 39–46 – 39–46 .
   Web of Science ®Google Scholar
• Posner , M.A. 1966 . The humic acids extracted by various reagents from a soil . J. Soil Sci. , 17 : 65–78 – 65–78 .
   Web of Science ®Google Scholar
• Powell , H.K.J. and Town , R.M. 1992 . Solubility and fractionation of humic acid; effect of pH and ionic medium . Anal. Chim. Acta , 267 : 47–54 – 47–54 .
   Web of Science ®Google Scholar
• Schnitzer , M. and Schuppli , P. 1989a . Method for the sequential extraction of organic matter from soils and soil fractions . Soil Sci. Soc. Am J. , 53 : 1418–1424 – 1418–1424 .
   Web of Science ®Google Scholar
• Schnitzer , M. and Schuppli , P. 1989b . The extraction of organic matter from selected soils and particle size fractions with 0.5 M NaOH and 0.1 M Na4P2O7 solutions . Can. J. Soil Sci. , 69 : 253–262 – 253–262 .
   Web of Science ®Google Scholar
• Stevenson , F.J. 1994 . “ Extraction, fractionation, and general chemical composition of soil organic matter ” . In Humus Chemistry: Genesis, Composition, Reactions , 2nd ed. , 34–40 – 34–40 . Chichester : John Wiley and Sons, Inc. .
   Google Scholar
• Swift , R.S. 1985 . “ Fractionation of soil humic substances ” . In Humic Substances in Soil, Sediment and Water , Edited by: Aiken , G.R. , McKnight , D. , Wershaw , R.L. and MacCarthy , P. 387–408 – 387–408 . New York : John Wiley & Sons, Inc. .
   Google Scholar
• Walkley , A. 1946 . A critical examination of a rapid method for determining organic carbon in soils—Effect of variation in digestion conditions and of inorganic soil constituents . Soil Sci. , 63 : 251–263 – 251–263 .
   Web of Science ®Google Scholar