Towards digital soil morphometrics

• There is a range of new tools and techniques to describe and analyse soil profiles.
• Small depth increments can be sampled providing continuous depth functions of soil properties.
• Digital morphometrics and continuous depth functions may enhance our pedological understanding.

Digital soil morphometrics is defined as the application of tools and techniques for measuring and quantifying soil profile attributes and deriving continuous depth functions. This paper reviews how proximal soil sensing and other tools can be used in soil profile descriptions where techniques and toolkits have not changed in the past decades. The application of such tools is compared to standard soil profile descriptions for 11 common attributes: horizons, texture, color, structure, moisture, mottles, consistence, carbonates, rock fragments, pores and roots. These attributes are extensively used in soil classification and are indicative of many soil functions. There has been progress in distinguishing soil horizons, texture and soil color, mainly using vis–NIR, GPR and electrical resistivity. There is potential for in situ digital morphometrics for all attributes of a soil profile. Smaller depth increments can be sampled and analyzed, and that gives continuous depth functions of soil properties. The combined use of in situ digital morphometrics and continuous depth functions of soil properties may enhance our pedological understanding. It will take time before the toolbox of the field pedologists will be digitally enriched, but we think that digital soil morphometrics has the potential to complement existing description and analytical methods. It may yield new insights in soil horizonation, how soils form and how they could be classified.