Agrochemical Characteristics of Chernozems of Mountainous Shirvan Economic Region: A Case Study of Ismayilli District

Abstract

This study evaluates the impact of long-term anthropogenic land-use practices on the physicochemical, particle-size, and microaggregate properties of cultivated mountain chernozems in the Ismayilli district, Azerbaijan. Soil pit No. 4 was established in a cereal field in Rushan village, while pit No. 15 was excavated under a perennial vineyard in Ivanovka village. Results indicate that continuous annual grain cropping preserves organic matter and fine particulate matter within the surface plow layer (0–29 cm), yielding higher topsoil humus (3.48% vs 4.47%) and physical clay (<0.01 mm) concentrations (80.79%). This topsoil accumulation is driven by irrigation-derived silt inputs, active root-microbial activity, and humic aggregation that mitigates leaching. Conversely, perennial vineyard management induces organic matter depletion due to deep root absorption, while promoting downward clay illuvial redistribution (fine clay <0.001 mm reaching 26.04% at 135–241 cm depths). Profile pH transitions from slightly acidic surface horizons (5.79) to moderately alkaline subsoils (8.14). The base saturation remains exceptionally high, with exchangeable cations rising up to 65.92 mmol/100 g in deeper layers due to carbonate-rich parent rock weathering. Under N.A.Kachinsky’s classification, both profiles are categorized as medium-to-heavy clay variants. Overall, persistent agricultural regimes—specifically perennial viticulture versus seasonal cereal cropping—profoundly reshape organic carbon sequestration, moisture partitioning, and textural differentiation in mountain chernozems