The dynamic changes of
soil pH, Eh, active manganese and their relationship were studied in three acid
soils(brown-red soil, yellow-brown soil and red soil)by contrast with a calcareous alluvial soil collected from Hubei Province in pot experiment of
rape plant. The results showed that pH and Eh of the soils would decrease sharply within 80 d of the growth of rape. In the brown-red soil and yellow-brown soil with
acidification treatment the contents of the exchangeable Mn (EXC-Mn) rose, and it was positively correlated with carbonate bond Mn (
carb-Mn) during the first 70d in the growth of rape. The increase of EXC-Mn was later than that of CARB-Mn. During the 30-90d, CARB-Mn concentrations were correlated with easily reducible oxide Mn (ERO-Mn). For every tested soil, the values of pe + pH remained stable with changes of pH and Eh. The models of soil pH, Eh and EXC-Mn could better reflect the relationship of the three factors in the acid soils with acidification except the red soil. Electrical pair MnO 2/Mn 2+ in the brown-red soil would be a better description to dynamic change of Mn oxides to Mn 2+ ion. And electrical pairs MnOOH/MnO would be main pattern in process of oxidation-reduction in the yellow-brown soil. The dissolution of MnO may be the reason of increase of Mn 2+ ion in this soil at the acidification condition. The experiment also showed that the radio of Mn/Fe of the plant increased significantly with enhancing of
Mn toxicity in rape, this change would be more obvious than that of the radio of Mn/Fe in corresponding soil acidification.
More abstracts about the Dynamic relationship between soil active Mn and pH, Eh in acid soils and its biological response