Determination of the effect of temporal and spatial changes in land use on dynamic soil properties and carbon stocks in major soil series in Çukurova Region

This study was conducted in the Çukurova Delta, located in southern Turkey along the Mediterranean coast. By comparing the region's detailed digital soil map with satellite images from Landsat 8 OLI, Spot5, and Spot6 from 2016, as well as Landsat 5 TM/ETM images from 1986, agricultural lands in the plain were examined in two categories: field crops and orchards. The spatial and temporal changes in the land use patterns of the prevalent soil series (Arıklı, Çanakçı, Arpacı, Yenice, Oymaklı) were identified. A total of 48 profile pits were excavated to represent both field and orchard uses and historical profile points for each series. From these pits, 190 soil samples were collected based on horizons, covering all horizons that could define the effective root depth, and soil analyses were conducted. Based on these results, temporal and spatial changes in soil dynamics were determined, and comparative statistical and geostatistical analyses of soil parameters were performed. Significant reductions in salinity were observed across all series, confirming the success of the drainage practices implemented by the State Hydraulic Works (DSİ). While a slight decrease in pH levels was observed in the Arıklı series, increases in pH were recorded in the Arpacı and Oymaklı series. Variogram analyses confirmed the spatial dependency of carbon stocks in all series using an exponential model; the Çanakçı series exhibited a homogeneous distribution, the Arpacı series showed an irregular distribution, and the Oymaklı series demonstrated a stronger spatial dependency of carbon stocks compared to the other series. The transformation from fields to orchards significantly increased soil carbon stocks in all series, with fruit orchards demonstrating a higher carbon storage capacity compared to agricultural fields. Between 1985 and 2017, soil organic carbon stocks in the Çukurova Region exhibited a general annual decrease of -1,467.68 to -2,869.80 tons/year due to unsustainable practices, despite localized increases resulting from the conversion to garden areas. Spatial and temporal changes were examined through statistical approaches, assessing how the agricultural use of prevalent series has changed and the effects of these changes on soil properties, soil health, and fertility. These analyses will contribute to a better understanding of natural processes and human impacts in the study area, aiding in natural resource management, sustainability, and environmental protection strategies. Keywords: Land Cover/Land Use, RS and GIS, Soil Series, Soil Dynamics and Carbon Stock Land Degradation Neutrality.