Relationship of Soil Crust Morphology to Inter‐rill Erosion Parameters

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Abstract
Research on soil surface sealing and crust formation has taken two approaches: (i) measurement of common soil erosion parameters such as infiltration, permeability, detachment, and strength and (ii) observation of seal or crust morphology using both microscopic and submicroscopic techniques. The purpose of this research was to combine the two approaches to extend our knowledge of surface sealing and crusting and its role in the erosion process. Eight soils with exchangeable sodium percentages (ESP) −1 for 1 h. Seal and crust formation were investigated by measuring splash and wash erosion, single waterdrop splash, and fall‐cone strength and by observing scanning electron microscope (SEM) and thin‐section photographs. Medium‐textured soils (five silt loams and a silty clay loam) developed homogeneous, silty surface seals of high strength ranging from 14 to 43 kPa and low splash detachment. Splash amounts for single drop impact ranged from 0.8 to 1.8 mg soil per drop, and for multiple raindrops in erosion pans, from 9 to 26 g soil during the final 5 min of a 60 min rain. For a clay soil, no morphological evidence of crusting was observed; strength of the seal was low (6.4 kPa) and splash amount was high (40.0 g in 5 min). For a sandy loam soil, splash was high (41.8 g) and strength, low (10.8 kPa). Crust morphology indicated slight crusting. The subjective nature of interpreting SEM and thin section photographs makes it difficult to draw conclusions about erosion processes or rates.