The nature of parent materials in Saskatchewan

  We have discussed the influence of parent material, climate, vegetation, topography, time and man on soil genesis or pedogenesis. This post is dedicated to exploring more fully the role of parent material in the pedogenesis of Saskatchewan soils. Parent material is unconsolidated rock and mineral material which subject to the forces of weathering produces a soil with its characteristic horizons. This slow paced weathering process (encompassing 100's to 1000's of years) commences at the surface, the interface between parent material and the environment. With time, the forces of weathering exert their influence to greater and greater depths, however the intensity of the process is reduced with depth. Soil layers or horizons emerge, first an A horizon and subsequently a B horizon. If the forces of weathering are more intense the depth of the A and B horizons will generally be greater.  At a certain depth, which is determined by weathering intensity, the pedogenic forces have little or no affect on the rock and mineral material. At this point we recognize the C horizon, the more or less unaltered parent material.

                               
       Figure 1   Typical horizon development grassland soil                

  The last ice age in Saskatchewan's prehistory is responsible for deposition of most parent materials. A consequence of the glacial activity is the incorporation of large amounts of limestone into this parent material. Saskatchewan parent materials are therefore generally referred to as calcareous, with neutral to basic soil pH values. In the 10,000 to 15,000 years since the last glaciation, the lime content of the A and B horizons has slowly weathered away, however the C horizon which is relatively unaffected by weathering  has retained its lime content. The presence of lime is easy to detect by applying dilute hydrochloric acid (HCL).  The HCL releases CO2 from the limestone and produces a characteristic fizzing or effervescence. The depth to the C horizon can be easily determined by exposing the soil profile to dilute HCL. Using a plastic squirt bottle, apply a small stream of acid to the soil profile starting at the surface and proceeding downward. When fizzing appears it is an good indicator that you have reached the lime and therefore the C horizon. Visit SLSC 240 online and view the discussion by Dr. Anderson about soil horizons, He makes use of HCL to locate the C horizon. Go to the online course here then to module 6, section 6.1, and view the quicktime video discussing soil profile identification.