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Determination of Acidity in Soil Organic Matter
Author(s) -
Schnitzer M.,
Gupta Umesh C.
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/sssaj1965.03615995002900030016x
Subject(s) - chemistry , organic matter , decarboxylation , titration , soil organic matter , environmental chemistry , soil water , organic chemistry , catalysis , soil science , environmental science
The suitability of the Ca(OAc) 2 and Ba(OH) 2 methods for the determination of COOH groups and of “Total Acidity” [sum of COOH + acidic (phenolic) OH] in soil organic matter preparations was evaluated. In addition, COOH groups and “Total Acidity” were also determined by decarboxylation and discontinuous titrations, respectively. These methods were used for the analysis of functional groups in three different humic and three fulvic acids and in 10 known organic compounds, representing types of structures that might occur in humic and fulvic acids. The Ca(OAc) 2 method was found to be suitable for the analysis of COOH groups in most of the known compounds and in the soil organic matter preparations investigated. The Ba(OH) 2 method was found to react with acidic hydrogens in both aliphatic and aromatic compounds and was not specific for phenolic OH groups. However, on the basis of available experimental evidence it is believed that the Ba(OH) 2 method measures phenolic OH groups in soil organic matter. Both the Ca(OAc) 2 and Ba(OH) 2 methods are simple and require neither elaborate equipment nor special skills. They appear to be suitable for use in the routine analysis of purified organic matter.