Forms of Mn in soils affected by a forest fire

Here we consider the total content of Mn and the fraction corresponding to exchangeable forms, combined with organic matter and easily reducible fractions, in soils affected by a forest fire, compared with control soils which are not affected. We observe that there is a significant increase in the total content of Mn, and also of easily reducible oxide forms. Nevertheless, the content of exchangeable Mn does not show any variation when compared with control soil and appears to be significantly correlated with that corresponding to forms of Mn combined with soluble organic matter in a solution of sodium pyrophosphate + sodium hydroxide.