Evaluation of RothC model for predicting soil organic carbon stock in north-west Ethiopia

Authors: GEREMEW, B - Ethiopia Haramaya University; TADESSE, TSEGAYE - University Of Nebraska; BEDADI, BOBE - Ethiopia Haramaya University; Gollany, Hero; TESFAYE, KINDIE - International Maize & Wheat Improvement Center (CIMMYT); ASCHALEW, ABEDE - Bahir Dar University; TILAYE, AMSALU - International Livestock Research Institute (ILRI) - Kenya; ABERA, WELETAW - International Maize & Wheat Improvement Center (CIMMYT)

Submitted to: Environmental Challenges
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2024
Publication Date: 4/5/2024
Citation: Geremew, B., Tadesse, T., Bedadi, B., Gollany, H.T., Tesfaye, K., Aschalew, A., Tilaye, A., Abera, W. 2024. Evaluation of RothC model for predicting soil organic carbon stock in north-west Ethiopia. Environmental Challenges. 15. Article 100909. https://doi.org/10.1016/j.envc.2024.100909.
DOI: https://doi.org/10.1016/j.envc.2024.100909

Interpretive Summary: Assessing soil organic carbon (SOC) is vital as it plays a significant role in water retention, soil health, nutrient cycling, greenhouse gas emissions, and pollutant reduction, which further enhances sustainable agricultural production and food security. Thus, the Rothamsted Carbon (RothC) model was applied to assess the current and future SOC stocks in the Anjeni watershed using long-term climate, soil, and land management inputs. RothC was initialized with long-term SOC, land management, and climatic data from the Anjeni watershed in northwest Ethiopia. There was a very good correlation (0.77 and 0.86) between simulated and observed SOC in 1986 and 2021, suggesting that the model has a potential to characterize the SOC of Anjeni watershed. Then, the RothC was used to project SOC in the watershed for 30 years, (2022 to 2052) under three slope gradients and land use type scenarios. For the 30-year projection, different possible scenarios were considered that include: 1) business as usual (BAU); 2) low; 3) medium; and 4) high slope gradients. The result indicated that in the low slope gradient and all land use types, the current BAU simulated SOC is less than future, low, medium, and high scenarios. Grass/fallow land had highest current and projected SOC compared to cultivated land and plantation forest. Furthermore, grass/fallow land of gentle slope gradient had higher SOC compared to the middle and high elevation section of the watershed. Overall, the model projected an increase in SOC under different scenarios that would improve water retention, nutrient cycling, soil aeration, soil health, and reduces greenhouse gas emissions, which in turn could enhance agricultural productivity, food security and sustainable development.

Technical Abstract: Assessing soil organic carbon (SOC) is vital as it plays a significant role in water retention, soil health, nutrient cycling, greenhouse gas emissions, and pollutant reduction, which further enhances sustainable agricultural production and food security. Thus, the Rothamsted Carbon (RothC) model was applied to assess the current and future SOC stocks in the Anjeni watershed using long-term climate, soil and land management inputs. RothC was initialized with long-term SOC, land management, and climatic data from the Anjeni watershed in northwest Ethiopia. The correlation coefficient between simulated and observed SOC in 1986 and 2021 were 0.77 and 0.86 respectively, suggesting that the model has a potential to characterize the SOC of Anjeni watershed. Then, the RothC was used to project SOC in the watershed for 30 years, from 2022 to 2052 under three slope gradients and land use type scenarios. For the 30-year projection, different possible scenarios were considered that include: 1) business as usual (BAU); 2) low; 3) medium; and 4) high slope gradients. The result indicated that in the lower slope gradient, in all land use types, the current BAU simulated SOC is less than future, low, medium, and high scenarios. Grass/fallow land had highest current and projected SOC compared to cultivated land and plantation forest. Moreover, grass/fallow land of gentle slope gradient had higher SOC as compared to the middle and high elevation section of the watershed. Overall, the model projected an increase in SOC under different scenarios that would improve water retention, nutrient cycling, soil aeration, soil health, and reduces greenhouse gas emissions, which in turn could enhance agricultural productivity, food security and sustainable development.