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The Effect of Periodate Oxidation on the Strength of Soil Crumbs: I. Qualitative Studies
Author(s) -
Clapp C. E.,
Emerson W. W.
Publication year - 1965
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1965.03615995002900020007x
Subject(s) - chemistry , extraction (chemistry) , soil water , sodium periodate , organic matter , dispersion (optics) , sodium hexametaphosphate , pyrophosphate , sodium , reagent , nuclear chemistry , inorganic chemistry , chromatography , geology , organic chemistry , soil science , physics , optics , enzyme
Various methods of extraction and oxidation of soil organic matter were used in combination with a sodium saturation technique to assess the binding strength of wet soil crumbs. The procedure consisted of equilibrating a few 3‐ to 5‐mm crumbs with 0.05 m NaCl, treating the crumbs with chemical reagents to remove the effective stabilizing components, and then observing the degree of slaking and dispersion of the crumbs when the sodium ion concentration is reduced. For crumbs from predominantly montmorillonitic or illitic soils, the dispersion solution was either 0.01 m NaCl buffered with p ‐nitrophenol at pH 7 or 0.025 m Na 2 B 4 O 7 at pH 10. For kaolinitic soils a more severe dispersion technique was required. The stability of crumbs formed under long‐term grass was reduced greatly by oxidation of the organic matter with 0.05 m NaIO 4 followed by extraction with Na 2 B 4 O 7 . Complete dispersion in Na 2 B 4 O 7 or NaCl/Na p ‐nitrophenol was obtained when a preliminary extraction with neutral Na 4 P 2 O 7 was followed by periodate oxidation. The stability of corresponding cultivated crumbs was destroyed completely without pyrophosphate extraction in a shorter period of oxidation. Surface crumbs from wooded sites on the same soils showed extreme resistance to all treatment combinations. It appears that there are two types of polymeric organic material binding the grassland crumbs together, one extractable by pyrophosphate and the other oxidizable by periodate. Samples from Houston Black clay behaved anomalously until the CaCO 3 was removed by dilute HCl treatment in the cold. The latter process in itself caused no loss in strength of the crumbs.