Distribution and Factor Analysis of Soil Organic Carbon in Soils for Grapevines from Selected Microlocations in the Ovče Pole Vine District

Soil organic carbon (SOC) represents a fundamental indicator of soil quality, directly influencing nutrient cycling, structural stability, and long-term sustainability in viticultural systems. This study evaluates the distribution of SOC and its controlling factors in vineyard soils from six microlocations within the Ovče Pole wine-growing district (North Macedonia). A total of 18 composite soil samples were collected from the surface layer (0-30 cm) and analyzed for SOC using the Walkley-Black titrimetric method, a validated and widely applied procedure for routine soil carbon determination. The obtained SOC values ranged from 0.76% to 1.32%, with a mean value of 1.13%, indicating predominantly low to moderate organic carbon status. These levels are typical for soils under semi-arid climatic conditions and intensive agricultural use, where organic matter inputs are limited and mineralization processes prevail. The relatively narrow variability of SOC suggests a degree of uniformity in soil management practices across the studied microlocations, but also points to inherent constraints in carbon accumulation related to soil type and environmental conditions. Multivariate statistical analysis (factor analysis) revealed two dominant factors explaining the majority of variability in soil properties. The first factor (45.7% of total variance) showed strong positive loadings for organic matter (OM) and total nitrogen (N), representing a fertility driven component and confirming the tight coupling between carbon and nitrogen cycles in vineyard soils. The second factor (24.2% of total variance) was associated with soil pH and CaCO₃ content, highlighting the influence of alkaline and calcareous conditions on SOC dynamics and nutrient availability. Overall, the results underscore the importance of targeted soil carbon management strategies to enhance SOC levels, contributing to improved soil health, climate resilience, and sustainable viticulture in the Ovče Pole region.