Grazing exclosures increase soil organic carbon stock at a rate greater than “4 per 1000” per year across agricultural landscapes in Northern Ethiopia

Publication Type

Journal Article

Name of Author

• Florent Noulèkoun, Korea University
• Emiru Birhane, Nord Universitet, Bodo, Norway
• Habtemariam Kassa, Centre for International Forestry Research, Addis Ababa, Addis Ababa, Ethiopia
• Alemayehu Berhe, Wukro College of Agricultural Polytechnic, Tigray, Ethiopia
• Zefere Mulaw Gebremichael, Adigrat University, Ethiopia
• Nuru Mohammed Adem, Afar Pastoral and Agro-Pastoral Research Institute, Semera, Ethiopia
• Yigremachew Syoum, Ministry of Environment, Forest and Climate Change, Addis Ababa, Ethiopia
• Tefera Mengistu, Ministry of Environment, Forest and Climate Change, Addis Ababa, Ethiopia
• Bekele Lemma, Hawassa University, Ethiopia
• Nigussie Hagazi, World Agroforestry Center, Addis Ababa, Ethiopia
• Haftu Abrha Mengesha, University Felix Houphouët-Boigny (U-FHB), Côte d'IvoireFollow
• Meley Mekonen Rannestad, Norwegian University of Life Sciences (NMBU), Norway
• Sylvanus Mensah, Universität Freiburg, Freiburg im Breisgau, Germany

Publication Date (Issue Year)

2021

Journal Name

Science of the Total Environment,

Abstract

The establishment of grazing exclosures is widely practiced to restore degraded agricultural lands and forests. Here, we evaluated the potential of grazing exclosures to contribute to the “4 per 1000” initiative by analyzing the changes in soil organic carbon (SOC) stocks and sequestration (SCS) rates after their establishment on degraded communal grazing lands in Tigray region of Ethiopia. We selected grazing areas that were excluded from grazing for 5 to 24 years across the three agroecological zones of the region and used adjacent open grazing lands (OGLs) as control. Soil samples were collected from two depths (0–15 cm and 15–30 cm) and SOC and aboveground C stocks were quantified in both exclosures and OGLs. The mean SOC stock and SCS rate in exclosures (0–30 cm) were 31 Mg C ha⁻¹ and 3 Mg C ha⁻¹ year⁻¹, which were respectively 166% and 12% higher than that in the OGLs, indicating a positive restoration effect of exclosures on SOC storage. With increasing exclosure age, SOC stock and SCS rate increased in the exclosures but decreased in the OGLs. Higher SOC stock and SCS rate were recorded in 0–15 cm than in 15–30 cm. The relative (i.e., to the SOC stock in OGLs) rates of increase in SOC stocks (70–189‰ year⁻¹) were higher than the 4‰ year⁻¹ and were initially high due to low initial SOC stock but declined over time after a maximum value of SOC stock is reached. Factors such as aboveground biomass, altitude, clay content and precipitation promoted SOC storage in exclosures. Our study highlights the high potential of exclosures for restoring SOC in the 0–30 cm soil depth at a rate greater than the 4‰ value. We argue that practices such as grazing exclosure can be promoted to achieve the climate change mitigation target of the “4‰” initiative.

Keywords

soil organic carbon, agricultural landscapes, Northern Ethiopia

Rsif Scholar Name

Haftu Abrha Mengesha

Rsif Scholar Nationality

Ethiopia

Cohort

Cohort 2

Thematic Area

Climate Change

Africa Host University (AHU)

University Felix Houphouët-Boigny (U-FHB), Côte d'Ivoire

Funding Statement

We are grateful to the Strategic Climate Institutions Program (SCIP) for funding this project. As SCIP is financed by the Governments of the UK, Norway, and Denmark, our sincere thanks are also extended in appreciation to the people and governments of these three countries for their support. Florent Noulèkoun is grateful for the support provided by the BK21 (Brain Korea 21 Program for Leading Universities and Students) FOUR program (Grant No. 4120200313708) and the Grant No. 2019R1I1A1A01064336

Recommended Citation

Noulèkoun, F., Birhane, E., Kassa, H., Berhe, A., Gebremichael, Z. M., Adem, N. M., Syoum, Y., Mengistu, T., Lemma, B., Hagazi, N., Mengesha, H. A., Rannestad, M. M., & Mensah, S. (2021). Grazing exclosures increase soil organic carbon stock at a rate greater than “4 per 1000” per year across agricultural landscapes in Northern Ethiopia. Science of the Total Environment,, 782, 146821. https://doi.org/10.1016/j.scitotenv.2021.146821