Diagnostics of hydrological properties of soils of the Sambian plains based on aerial photography and electromagnetic induction

The article focuses on studying the influence of the spatial heterogeneity of lithological and geomorphological conditions on the hydrological characteristics of the soils of the Sambian Plain using aerial photography and electromagnetic induction methods. From 2020 to 2022, at the “Pereleski” test site, topographic surveys were conducted using UAV, soil-forming material heterogeneity was diagnosed, and field measurements of particle size distribution, moisture content, and the degree of gleyization were carried out in reference soil profiles (n = 4). Additionally, the morphology of soil horizons and the degree of gleyization in additional sampling points (n = 18) were described. The method of electromagnetic induction profiling using the EM38-MK2 established a reliable strong correlation between silt content and apparent soil electrical conductivity (R² = 0.88). Multidimensional scaling enabled the ranking of all soil descriptions at the test site by the degree of gleyization, providing a quantitative assessment of the depth and duration of waterlogging in soil profile. Morphometric characteristics and electrical conductivity in the layers of 0-0.375 m; 0-0.75 m; and 0-1.5 m were compared with the calculated gleyization intensity index of soils. Linear regression analysis revealed a relationship that explains 81% of the variability in soil gleyization based on two factors: electrical conductivity in the 0-1.5 m layer and the topographical positional index within a 10 m radius. Consequently, soils were ranked according to the combined characteristics in a sequence of increasing gleyization intensity: Endogleyic Cambisols - Gleyic Albeluvisols- Haplic Gleysols, linked to the differences in their long-term average water regimes. The identified heterogeneity of micro- and mesorelief and the high variability of the soil-forming materials resulted in the alternation of these soils in the form of soil micro-mosaics, indicating the intra-field heterogeneity of the agroecological conditions of the test site.