Digital soil morphometrics of coarse fragments and horizon delineation in soil profiles from Central Mexico

Abstract

In this study, we developed a method that allows the delimitation of horizons and the quantification of coarse fragments in soil profiles from volcanic areas using digital images. The delineation of the soil profile horizons included the following phases: pre-processing of the digital image, extraction of color systems from the pre-processed image, k-means segmentation of the HSV and CIE L*a*b* color systems, delineation of the horizons, and determination of the horizon characteristics. The coarse fragments were quantified in the following three phases: superpixel analysis of the soil profile image, histogram classification of the image objects, and extraction and quantification of the coarse fragments. For horizon delineation, the HSV color system performed better for the Eutric Andic Cambisol (Loamic, Ochric), and the CIE L*a*b* system performed better for the Eutric Skeletic Mollic Silandic Andosol (Loamic). The RGB image and the S component of the HSV system demonstrated similar coarse fragment volume calculation performance for the Eutric Andic Cambisol (Loamic, Ochric), whereas the S component worked best for the Eutric Skeletic Mollic Silandic Andosol (Loamic). We created a graphic decision-making system for the delineation of soil horizons and for the quantification of coarse fragments in digital images of soil profiles.