Soil Lime Requirement by Direct Titration with Calcium Hydroxide. (5606)
Authors:
D. Kissel* - Univ. of Georgia M. Liu - Univ. of Georgia R. Isaac - Univ. of Georgia
Abstract:
Direct titration of acid surface soils is often used to measure soil acidity, but it has not been used for routine determination of the lime requirement (LR) in soil testing laboratories, because multiple additions of base are too time consuming. Recent studies have shown that soil pH as a function of added base can be described well by a linear equation, and that adequate accuracy for the LR is possible with one addition of base and two pH measurements when carried out in 0.01 molar calcium chloride. In order to implement this procedure for routine use, robotic pH
instrumentation and software was modified to facilitate two pH measurements, one before and one after the addition of two ml of saturated calcium hydroxide by a burette pump.Trials were then begun to compare LR by titration with those by the Adams-Evans procedure. Lime requirements for over 500 client samples were similar by the two methods, although the titration procedure gave higher results at low values of LR and slightly lower values at high values of the LR. Comparisons were also made of soil pH in water with those in 0.01 molar calcium chloride (1:1 soil:solution ratio). The differences in soil pH varied considerably but averaged 0.6 pH units higher in water.
Speaker Information: David Kissel, Univ. of Georgia, Soil, Plant, and Water Laboratory, 2400 College Station Road, Athens, GA 30602; Phone: 706 542-5350;
E-mail: [email protected]
Session Information: Wednesday, November 3, 2004, 8:30 AM-10:00 AM Presentation Start: 9:05 AM
