SEDIMENTS, SEC 2 • PHYSICAL AND BIOGEOCHEMICAL PROCESSES • RESEARCH ARTICLE Soil conservation practices contribution in trapping sediment and soil organic carbon, Minizr watershed, northwest highlands of Ethiopia Mulatie Mekonnen 1 & Mekonnen Getahun 2 Received: 15 May 2019 /Accepted: 10 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Purpose Globally, land degradation and climate change are priority problems. Therefore, this study was conducted in Minizr catchment in the northwest highlands of Ethiopia to investigate the sediment and sediment organic carbon (SOC) trapping role of soil and water conservation practices (SWCPs) constructed inside fields, check dams (CDs) constructed inside gullies and micro- trenches constructed on degraded grazing lands, which would help to reduce land degradation and climate change. Our three research questions were: How much sediment was trapped by SWCPs? How much SOC was trapped by SWCPs? What was the role of SWCPs in mitigating climate change? Materials and methods Google Earth Imagery was used to map the SWCPs constructed inside fields; a Digital Elevation Model (ASTER DEM 20 m) was used to delineate the boundary of the study watershed and to evaluate elevation and slope character- istics, and GPS was used to collect watershed outlet coordinate points, CD locations and to accurately digitize SWCPs. Three different SWCPs, five different CDs and 30 micro-trenches were evaluated for their sediment and SOC trapping efficiency. The experiment was designed in three treatments with three replications, except for the CD studies. The volume of sediment trapped was quantified using field measurements of the deposited sediment and SOC was determined in a soil laboratory. Results and discussion The investigated SWCPs, CDs and micro-trenches trapped ~584,745 kg SOC together with 32,105 t of sediment. The percentage SOC was higher in the CD sediments (1.98%) than SWCPs (1.38%) and micro-trenches (1.49%). A large amount of SOC was deposited in vegetative-supported CDs than CDs constructed from structures alone, i.e. CDs supported with vegetative practices trapped more SOC. Conclusions In general, SWCPs, CDs and micro-trenches were found to reduce soil erosion or land degradation by enhancing sediment deposition. They also trapped large amounts of SOC together with the sediment, which can reduce the greenhouse gases emission to the atmosphere. Therefore, governmental and non-governmental organizations and professionals should also con- sider SWCPs as climate change mitigation measures, like that of afforestation/plantation. Keywords Check dams . Climate change mitigation . Micro-trenches . Sediment deposition . Sediment organic carbon trapping . SWCP 1 Introduction Global warming will continue being a critical problem in the twenty-first century due to increased carbon dioxide and other greenhouse gases (GHGs) concentration in the atmosphere (IPCCC 2013, 2014). The atmospheric concentrations of the GHGs carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous ox- ide (N 2 O) is increasing from time to time. The concentration of atmospheric CO2 increased from about 280 ppm (ppm) by volume prior to 1850, to 396 ppm in 2014 (IPCC 2014). On long-term basis, atmospheric CO 2 has increased from about 180 to 280 ppm since the last glacial period, adding ~220 PgC Responsible editor: Nikolaus Kuhn * Mulatie Mekonnen mulatiemekonneng@gmail.com 1 Department of Natural Resource Management, Geospatial Data and Technology Center, College of Agriculture and Environmental Sciences, Bahir Dar University, P.O.Box 1188, Bahir Dar, Ethiopia 2 Amhara Design and Supervision Works Enterprise, Bahir Dar, Ethiopia Journal of Soils and Sediments https://doi.org/10.1007/s11368-020-02611-5