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Report on Methods of Determination of Exchangeable Magnesium in Soils
Author(s) -
Shaw W. M.
Publication year - 1957
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/sssaj1957.03615995002100020007x
Subject(s) - magnesium , environmental science , chemistry , environmental chemistry , organic chemistry
T N THE fall of 1953, a collaborative study of methods for the determination of exchangeable magnesium in soil extracts was initiated. A survey having 49 respondent college and federal laboratories revealed that 12 laboratories were using a thiazole yellow colorimetric method; 9 were using versenate titration; 9 were using titration of magnesium ammonium phosphate; 5 were determining magnesium gravimetrically as the pyrophosphate; and 6 were using the Beckman flame spectrophotometer. The use of 4 additional methods was distributed among the remaining 8 laboratories. During 1954 magnesium solutions were distributed to 32 soil scientists, each of whom analyzed the solutions by the method commonly employed in his laboratory. Results of this study may be summarized as follows: 1. The thiazole yellow methods gave average results closer to the true values than the other methods, and there was better agreement among collaborators at low concentrations. 2. The flame photometer methods gave consistently low results. Expressions of precision with this method are included as a part of table 1. 3. EDTA titration gave high results and agreement among collaborators was lower than average.