Conservation Effects on Soil Quality and Climate Change Adaptability of Ethiopian Watersheds

Mengistu, D. et al., 2016. Land Degradation and Development

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Abstract

This study analyzes effects of soil and water conservation (SWC) on soil quality and implications to climate change adaptation and mitigation in the Upper Blue Nile River Basin of Ethiopia by using the Anjeni watershed as a case study site. Disturbed and undisturbed soil samples were collected from two sub-watersheds of Anjeni: the Minchet sub-watershed (with SWC measures) and the Zikrie sub-watershed (without SWC measures). Soil samples were taken from 30-cm depth from five representative landscape positions and analyzed following the standard soil lab analysis procedures. The results show that soils from the conserved sub-watershed had improved quality indicators compared with those from the non-conserved site. Significant improvement due to SWC measures was observed in the soil hydrological [total moisture content (+5·43%), field capacity (+5·35%), and available water capacity (+4·18%)] and chemical [cation exchange capacity (+4·40 cmol(+) kg-1 ), Mg2+ (+1·90 cmol(+) kg-1 ), Na+ (+0·10 cmol(+) kg-1 )] properties. SWC interventions significantly reduced soil erosion by 57–81% and surface runoff by 19–50% in the conserved sub-watershed. Reduction in soil erosion can maintain the soil organic carbon stock, reduce the land degradation risks, and enhance the C sequestration potential of soils. Therefore, adoption of SWC measures can increase farmers’ ability to offset emissions and adapt to climate change. However, SWC measures that are both protective and sufficiently productive have not yet been implemented in the conserved sub-watershed. Therefore, it is important that SWC structures be supplemented with other biological and agronomic measures in conjunction with soil fertility amendments appropriate to site-specific conditions.

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