Direct titration for measurement of soil lime requirement.
(S08-kissel247907-poster)
Authors:
M. Liu* - University of Georgia D. Kissel - University of Georgia
Abstract:
Direct titration of acid surface soils is often used to measure soil acidity. However, titration has not been used for routine determination of the lime requirement in soil testing laboratories, because it is too time consuming, requiring multiple additions of base and long equilibration times between additions. Since soil pH as a function of added base can be described well by a linear equation, titration may be adopted by soil testing laboratories using a minimum number of base additions followed by extrapolation to the target pH. Our objective was to evaluate the accuracy of simplified titration procedures using three additions of base and then using only one addition of base following the initial pH measurement.
Seventeen Georgia soils were studied by titrating them with calcium hydroxide in either water or 0.01 M calcium chloride. A 30 min interval time between additions gave greater lime requirements than 15 min equilibration, but the same as 45 min equilibration. A three addition titration with 30 min interval
between additions estimated approximately 80 % of the lime requirement determined with the standard three day incubation with calcium hydroxide. When only one base addition was used, the lime
requirement was 69% of the standard using the initial pH in water, but when done in 0.01 M calcium chloride, 88% of the lime requirement was measured.
Speaker Information: David Kissel, University of Georgia, Soil Plant Water Laboratory 2400 College Station, Athens, GA 30602; Phone: 706 542-5350; E-mail: [email protected]
Session Information: Tuesday, November 4, 2003, 2:30 PM-4:30 PM Presentation Start: 2:30 PM (Poster Board Number: 1434) Keywords: lime requirement; soil acidity; titration; soil testing