Effect of land use and topographic factors on soil organic carbon content and mapping of organic carbon distribution using regression kriging method

Abstract

The study investigates the effects of land use type and topographic properties on soil organic carbon (SOC) in a catchment with a high annual soil loss due to erosion. In addition, the SOC content was determined by modeling the SOC distribution map using the regression-kriging (RK) method. Within this context, the effects of forest land (FL), degraded forest (DF), barren area (BA) and agricultural areas (AA) and different topographic factors (elevation, slope, aspect) on SOC were examined. The catchment had an area of 10675 ha and 429 soil samples were collected to determine the SOC contents of the soils. The results revealed that land use type had a significant effect on SOC and FL had the highest SOC content. However, there was no relationship between elevation and SOC. On the other hand, the SOC content decreased inversely proportional to the slope of the lands. The soil loss due to erosion is considered an important factor causing the decrease. The aspect of the land was also determined to have an important effect on the SOC content. The increase was mostly attributed to relatively less sunlight received by the northern slopes in Turkey. The lands on the northern slopes had the highest SOC content, while the lowest SOC content was determined in the southwest areas. The SOC contents depending on the land use type were close to each other according to the RK and normal regression methods. © 2020 Earth and Environmental Team, Romania.