A Method for 3D Soil Horizonation Using Digital Images

Abstract

Using digital images, we have created a three-dimensional (3D) model of spatial distribution of soil horizons with a mosaic structure. The technique was tested on the developed soddy–podzolic soil of the Chashnikovo Training and Experimental Soil Ecological Center. The 11 sections of the soil profile used to create the model show an area of 30 × 45 cm with a distance of 2.5 cm between the section. The correctness of color rendering of photographic images was checked using a portable spectrophotometer. The color rendition of the best images was corrected using the external standard method. The resulting images were used to create a batch processing file in SAGA GIS to obtain a three-dimensional data array on soil color in the CIE L*a*b* system. Using the Voxler 4 software, we have constructed a 3D model with dimensions of 45 cm (X) × 30 cm (Y) × 25 cm (Z) and a resolution of 0.5 cm (X) × 0.5 cm (Y) × 2.5 cm (Z). Analysis of the spatial distribution of color indicators and the use of the threshold value algorithm have identified horizons A1A2, A2, and A2B. Carbon stocks calculated for the same volume of soil using the 3D model are significantly (by 25%) lower than those calculated using the 2D model. The authors believe that the optical mapping method based on color indicators in the CIE L*a*b* system quite accurately reproduces the natural structure of the boundaries of soil horizons and can be used in further works on modeling and studying soil profiles with a mosaic structure.