IMPACT OF DRAINAGE ON IRON-MANGANESE NODULES

摘要

The Fe-Mn nodules chemical composition is assumed to be a reliable diagnostic criterion on the gleization rate for soils with eluvial-illuvial profile. However, the water regime transformation caused by drainage induces quick changes (probably in the first years after drainage) in their chemical properties, and in a certain time moment they become inadequate to the existing water regime. Hence, nodules lose their diagnostic importance. As common trends in Fe-Mn nodules alterations in intensively drained soils, the following ones are worth mentioning: decrease in number or complete disappearance of coarse fractions (> 3 or 5 mm); decrease of the total mass of nodules; lower sulphuric acid extractable Fe concentrations at the expense of those of Mn, with a drastic fall of total Mn pool; lower absolute values of bogginess coefficient. The tatter becomes no more suitable for diagnostic in the course of research aimed at drainage systems reconstruction.