In a laboratory setting, 10 new ceramic cup soil solution samplers, 10 samplers used 1 yr, and 10 used 6 yr were tested for consistency and uniformity of results. The new cups were flushed with acid and distilled water. The ceramic cups that had been installed in the field 6 yr produced samples with Mg, Na, NO3, and K concentrations that were consistently greater than or equal to samples from cups that had been installed for 1 yr. Both sets proauced concentrations greater than or equal to those from the new cups. After all three cup types were flushed with HCI and distilled water, a second comparison was made, and no significant differences were found in Ca and Mg concentrations in two sets of extracts. However, Na, K, and NO3 concentrations showed some variability. Flushing apparently returned the cation exchange of all cups to a more uniform status. Flushing will reduce plugging of the cup wall due to field use. However, acid flushing will reduce concentrations of the first set of extracted samples to less than that of the soil solution.
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