Influence of relief-soil relations on morphogenetic diagnostics of mountain gray-brown ordinary soils of the north-eastern part of the Lesser Caucasus of Azerbaijan

The aim of the study is to study the influence of different relief slopes on the morphogenetic diagnostics of Haplic Kastanozems in the northeastern part of the Lesser Caucasus. The study area is located at an altitude of 410-450m above sea level and is significantly dissected by slopes and valley-shaped microdeposits. The soil-forming rocks consist of deluvial carbonate clay-clayey sediments. The climate is dry subtropical, with an annual precipitation of 350-400mm and an average annual temperature of 11.8-12.5°C. A large-scale soil map (1:10000) of the study area was compiled based on the soil survey and preparation of the relief plastic map (1:10000). The soils of shady northwest-facing slopes and valley-shaped microdepressions are characterized by a relatively optimal moisture regime and the formation of a thick accumulative rot layer (AU=40-45cm) under vegetation cover, good supply of humus (2.6-3.5%), nitrogen (0.22-0.27), absorption capacity (26.0-31.4 mmol-eq), and an alkaline environment (pH=7.3-8.5). Characteristic diagnostic indicators are the leaching of carbonates from the upper layer of the soil profile (AU=0-25cm) and their accumulation in the middle part (CaCO3=5.2-8.3%), clayey granulometric composition (˂0.01mm=53.5-60.7%), density varying between 1.15-1.42 g/cm3, aboveground biomass of grasses amounting to 7.24 t/ha, and root mass amounting to 22.73 t/ha. The relatively dry microclimate conditions and exposure of the soils of sunny southeastern slopes to erosion processes have led to a significant decrease in the thickness of the accumulated carbonate layer (AUa=25-30cm), humus (1.9-2.1%), nitrogen (0.17-0.20%), absorption capacity (20.2-24.3 mmol-eq), aboveground biomass (4.79 t/ha) and root fraction (11.46 t/ha), and a relatively lightening of the granulometric composition (˂0.01mm=38.3-44.2%; ˂0.001mm=13.7-19.4%).