The purpose of this study was to characterize the soil organic carbon dynamics associated with four land-uses (cropland, grassland, shrubland, and forestland) in the upper Blue Nile Basin of the Ethiopian Highlands. We collected diverse biophysical data to allow spatial variability of soil organic carbon and factors contributing to this variation to be determined statistically, and used well established simulation models to interpret the data, predict long-term carbon dynamics and determine the potential for improvements in soil quality and mitigation of greenhouse gas emissions. The spatial variation in soil organic carbon in the 0-20 cm soil depth was significant across study areas (P-1-37.8 g kg-1), and between land-uses (P-1 in cropland and 43.0 g kg-1 soil in forestland). In a multiple linear regression model, among the 11 explanatory variables used, four (total nitrogen, shrubs, trees and land use) showed a significant positive effect (P-1, and grasslands by 3.5, 3.9 and 2.7 tha-1, while shrublands will build-up soil organic carbon by 0.6, 0.1 and 1.3 tha-1 at study sites. At one study site, forests, will further increase soil organic carbon by 6.7 tha-1 after 30 years. The significant positive impact of shrubs and trees on soil organic carbon suggests the need to focus on introduction of agroforestry systems in crop and grasslands.
This research was conducted with support from Nile Basin Development Challenge as part of the CGIAR Challenge Program on Water and Food (latterly the Water, Land and Ecosystem program) and ICRAF. We would like to thank the field team, who participated in the field data collection: Biadglign Demissie and Zelalem Hadush (Mekelle University), Tesema Bekele (Addis Ababa University), Mossisa Ararso and Tesfay Muluneh (Wellega University), Shibru Gutema and Tesfaye Korso (Diga District Agriculture Office), Belete and Benti (Jeldu District Agriculture Office), Daba Dendena (Addis Ababa IWMI) and Solomon Kebede (Addis Ababa ILRI). We would like to thank to Nigist Wagaye and Aschalew Teshome (Addis Ababa IWMI personnel) for their facilitation of field operation. We would also like to thank the authorities of Werota, Jeldu, and Diga districts and farmers for allowing us to conduct the field surveys. We are also grateful to the Bureau of agriculture and Administrative offices of Oromia and Amhara Regional States.
- Simulated soil organic carbon
- Soil organic carbon depletion
- Soil organic carbon stock
- Spatial and temporal dynamics of soil organic carbon stocks