Micromorphological Approach to Identify Polygenesis in Soils

It is often difficult to distinguish pedogenic features of different origins in soils that could have experienced multiple episodes of climatic changes during pedogenesis. However, in such cases, a micromorphological study of these soils could be potentially useful to provide a detailed record of the polygenetic pedofeatures and to reconstruct the pedogenic history. This chapter provides micromorphological evidence of polygenesis in IGP soils of the Gangetic Basin (GB) that developed on five soil-geomorphic surfaces for varied periods, that is, QIG1 (<0.5 ka), QIG 2 (0.5–2.5 ka), QIG3 (2.5–5.0 ka), QIG4 (5.0–8.0 ka), and QIG5 (10.0–13.5 ka) with increasing degree of soil development. The older soils >2.5 ka in age are marked by many polygenetic pedofeatures on account of climatic changes during pedogenesis in overbank sediments of the IGP. The polygenetic pedofeatures of the GB soils are characterized by degradation of the earlier clay pedofeatures and formation of newer illuvial pedofeatures, dissolution-reprecipitation of pedogenic CaCO3, and mineral alteration during the transition from humid-semiarid-humid phases of climates over the last 13.5 ka.