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An investigation on laboratory and field methods of determining the pH of soil suspensions
Author(s) -
Farr E.
Publication year - 1972
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740230906
Subject(s) - bromocresol green , bromocresol purple , soil water , soil test , environmental science , range (aeronautics) , field (mathematics) , environmental chemistry , chemistry , soil science , mathematics , chromatography , materials science , composite material , pure mathematics
A comparison was made between the pH values of soil samples, measured with a pH meter in the laboratory, and those obtained by using colorimetric indicator solutions in the field. Of the indicators tested, BDH Soil Indicator and bromocresol purple provided the closest overall comparison with laboratory results for soils with pH values from 3.8 to 7.8. Bromocresol green was useful only over a limited range (less than 5.2). Differences in procedure and analysis sometimes produced compensatory errors but the results did not often agree exactly and the magnitude of the discrepancy for any given soil was predictable only within fairly broad limits—the average standard deviation was 0.34 units and there was about a 75% chance of the result determined in the field being within 0.3 units of the result determined in the laboratory.