Micromorphological and Physico-chemical Characteristics of Soil Crust Types in Northwestern Alberta, Canada
- M. A. Arshad and
- A. R. Mermut
The micromorphology and submicroscopy of naturally-formed surface crusts in several soils from the Peace River region, alberta were studied in order to understand the types and mechanisms of crust formation. Although the soils studied contained stable aggregates in the dry state, these aggregates almost completely broke down when wet, leading to the crusting tendency of the soils. Other soil characteristics that likely induced the structural deterioration were high silt contents, exchangeable Na and Mg, and low organic matter contents. Three morphological types of surface crusts were identified, including (i) lamellar, (ii) sedimentational, and (iii) disruptional. Lamellar crusts were typical of soils high in clay and exchangeable Na and Mg. Sedimentational crusts were found in areas which were subject to large amounts of surface runoff and subsequent sedimentation of suspended materials. Disruptional crusts were formed by direct raindrop detachment of soil aggregates, subsequent disruption of aggregates, and a reduction of volume within the crust. Disruptional crust was the most common crust formed in the silty soils of the Peace River region. One characteristic, very common to all crust types, was the presence of 2 to 5 µm thick layers within the immediate surface that caused the complete sealing of the soil surface. The moisture content of the immediate surface layer determines the strength of the crust. Hence, water management and mulching is crucial for crust prone soils.
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