Ceramic suction samplers: A reliable method for extracting soil solutions for analysis

Abstract

Ceramic samplers are used to extract soil solutions at different depths from the soil profile for chemical analysis. The advantage of this method is that samples can be taken at any time provided that the soil water potential is high enough to allow extraction of the water from the soil. An investigation was conducted to determine to what extent the CEC (cation exchange capacity) and selectivity coefficients of the samplers might influence the chemical composition of the water samples collected. This was due to criticism that the accuracy of the method may be influenced by the CEC of the samplers. The CEC of four Soil Moisture ceramic cup soil water samplers was determined. Two of these samplers had previously been installed in the field and two were new. The CEC of the sampiers did not vary much, although the used samplers had higher CEC values, which were ascribed to the contribution of clay particles contaminating the ceramic material. Selectivity coefficients for different cation combinations were calculated using the Vanselow equation. The selective adsorption of certain cations requires that negligibly small amounts of extracted soil solution be discarded. This makes the ceramic soil water samplers suitable for solution cation analysis.