Controlling factors of soil organic and inorganic carbon in North Adana, Türkiye

Abstract

In many soils of arid and semi-arid regions, the soil carbon pool consists of soil organic carbon (SOC) and soil inorganic carbon (SIC). Numerous studies have examined the relationship between the content of SOC and SIC in relation to various environmental factors. The northern region of Adana city in the Mediterranean region of Türkiye is characterized by a Mediterranean climate with about 600 mm of rainfall per year. Most studies in the region have focused on the impact of land degradation, such as urbanization and land use change, on stocks rather than the factors controlling SOC and SIC. The study area covered 9625 ha (>70 % Entisols) with an altitude ranging from 67 to 365 m. Soil samples were collected from 107 points at depths 0–30 and 30–60 cm, and from 17 pedons that were sampled by horizon. The spectral reflectance of the soil was measured using a vis-NIR spectrometer. SOC decreased with depth, while SIC increases regardless of land use. MAP and MAT did not show a significant effect on SIC concentrations. Soils derived from siltstone showed a large decrease in SOC concentration, while soils derived from conglomerate had an increase in SIC. High SOC concentrations were observed in the southern part of the region, while low SOC concentrations were observed from southwest to northeast of the study area. Dark colored soils had higher SOC and lower SIC values compared to light colored soils. In this area, SIC and SOC are controlled by soil characteristic and processes rather than by land use, topographic factors and rainfall and temperature.