Influence of the Composition of Parent Materials on Soil Formation in Manitoba1

The analysis of the major horizons of ten soil profiles was undertaken in an attempt to ascertain the effect of the composition of parent material on soil formation in well-drained Mankato till sediments, under various environmental conditions. The results showed that the composition of parent materials had a profound effect on the type of profile formed. Increasing amounts of inorganic carbonates restricted profile development and inhibited the decomposition of non-calcareous rock fragments. The amount of inorganic carbonates in the parent material has been a major factor in determining and differentiating certain great soil groups; furthermore, the mineralogical composition of the parent material also has been a determining factor in the formation of Brown Podzolic and Podzol soils. Weathering of non-calcareous minerals and rocks (except shale) was found to be comparatively slight; examination of the clay fraction revealed approximately equal percentages of the dominant types in each horizon.