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A digital morphometric approach for quantifying ped shape


Soil structure has important influence over soil hydraulic properties, crop production, infiltration, and flood mitigation. Despite the importance of soil structure, very little is known about how ped shape affects the soil properties that contribute to soil functioning and health. Part of the reason for this is that ped shape has been difficult to quantify and is, instead, described using subjective and categorical shape classes.

In a recently published article in the Soil Science Society of America Journal, researchers developed a method to quantify ped shape using several metrics obtained from image analysis of 2-D ped silhouettes. Using this approach, ped shapes can be described in terms of their circularity, roundness, major-axis ellipse angle, aspect ratio, solidity, and width-to-height ratio. Furthermore, these ped shape metrics can also be used to convert qualitative morphological descriptions of soil structure into quantitative continuous data. Circularity and width-to-height ratio were the most important metrics that were able to differentiate between traditional descriptions of ped shapes. The peds used in this study were classified into ped shape categories by surveying pedology students and professionals.

Soil profile diagram

These findings may open up the possibility of directly incorporating soil structure information into models of water flux, retention, infiltration, and erosion.

Read the full article in SSSAJ. Free preview Dec 21 - Dec 28