Soil Development as a Function of Time in The Punjab River Plains of Pakistan
1977
Ahmad, M. | Ryan, J. | Paeth, R. C.
Three soil series; Shahdara (Ustifluent), Sultanpur, (Ustochrept) and Bhalwal (Haplustalf), representing a chronosequence from the Punjab River plains of Pakistan, were studied with respect to morphological, chemical, physical, and mineralogical properties. These soils, developed in mixed mineral alluvium, represented the late Holocene, middle Holocene, and late Pleistocene surfaces and were estimated to be less than 100 years, around 2,300 years, and between 10,000 and 20,000 years old respectively. With increasing soil age, horizon differentiation and solum thickness increased while cutans and CaCO₃ concretions occurred in the oldest Bhalwal soil. Topsoil CEC and TEB values increased while both CaCO₃ content and the Ca:Mg ratio decreased. Significant changes occurred in the ratio of acid oxalate to citrate-dithionite extractable iron (Fe ratio). Textural gradation was in evidence in the two older soils. Illite and chlorite tended to decrease, and vermiculite and montmorillonite to increase with soil age. Despite variability in parent materials due to depositional stratification and preweathering, the changes in soil properties with age were mainly attributed to processes of soil formation.
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