Two charts comparing saturated hydraulic conductivity as function of clay content for temperate and tropical environments.
Saturated hydraulic conductivity Ksat is one of the most essential properties of soil hydraulic behavior that can be related to soil drainage, water retention, and erodibility characteristics. This figure shows Ksat as function of clay content for temperate and tropical environments (plot (a) shows data for tropical Brazil and (b) for Africa), illustrating that kaolinite-rich tropical soils have much higher conductivity than those in temperate regions with the same clay fraction. Symbols are data and lines are the estimates from a model developed in this study showing a great match with the data. Credit: Lehmann et al. [2021], Figure 2
Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Geophysical Research Letters

For many years, hydrologists and geomorphologists made no distinction between soils with different dominant clay minerals, despite their characteristic differences between tropical and temperate environments. Specifically, tropical regions are dominated by a different type of dominant soil clay mineral, kaolinite, that has a distinct impact on soil microstructure and mechanical properties.

Soils rich in kaolinite have been associated with soil hydraulic properties that deviate significantly from those for soils in temperate areas with the same clay content. Lehmann et al. [2021] develops novel models based on physical properties of clay mineral type to account for their hydraulic differences. This research develops new type prognostic equations describing soil hydraulic properties that can be used by the Earth-System Models to improve global predictions of water fluxes, erosion, and natural hazards.

Citation: Lehmann, P., Leshchinsky, B., Gupta, S., Mirus, B. B., Bickel, S., Lu, N., & Or, D. [2021]. Clays are not created equal: How clay mineral type affects soil parameterization. Geophysical Research Letters, 48, e2021GL095311.

―Valeriy Ivanov, Editor, Geophysical Research Letters 

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