Soil carbon and nitrogen stocks in traditionally managed rangeland biomes in Karamoja sub-region, Uganda

Abstract

Rangelands are known for their potential in mitigating rising atmospheric carbon dioxide (CO2) concentrations in the world. The objective of this study was to investigate the patterns of soil organic carbon (SOC) and nitrogen (N) in rangelands under traditional management systems in Karamoja sub-region in Uganda, with a view to facilitating the development of appropriate and strategic management practices for the rangeland resources. The study was conducted during the wet season of the sub-region. Four land use/cover types (cropland, grassland, woodland and thickets/shrubland) were laid out in a completely randomised design. Soil samples were collected from four plots each one measuring 50 m x 40 m in each land use/cover type. A diagonal design was used for sample collection at depths of 0 - 15 and 15 - 30 cm. Results showed that at both soil depths, croplands had the lowest mean SOC and highest N; while grasslands had the highest SOC. Also, cropland recorded the highest mean soil bulk density at both depths. Based on soil analysis only, this study showed that conversion to cropland over a specified period of time can considerably reduce the ability of rangelands to sequester carbon. Further studies to include assessment of carbon stocks in the respective vegetation biomass are recommended.