Incubation experiments with an acid, poorly drained soil
(Typic Albaqualf) showed that the level of extractable Mn
was increased by salt treatments. The relative order of the
salt effect was KBr > KCl > KNO? > K?SO?. Soil pH changes
accounted for the majority of the KNO? and K?SO? treatment
effects, but the KCl and KBr effects could not be explained on
this basis. In addition, ionic strength considerations and differential
biological activities were not found to be factors influencing
the K salt effects in the soil system. A hypothesis is
presented to explain the KCl or KBr effect, in which the anion
would function in an oxidation-reduction reaction. This hypothesis
is supported by the fact that the soil treated with KBr
contained more extractable Mn than that treated with KCl, in
accordance with theory. Theoretical calculations also suggested
the possibility that both Cl- and Br- could reduce the lower
valency Mn oxides under the experimental soil conditions
