Effect of community-based soil and water conservation practices on soil glomalin, aggregate size distribution, aggregate stability and aggregate-associated organic carbon in northern highlands of Ethiopia

Basic information

• Case ID: INT-251-1
• Intervention type: Combination
• Intervention description:

  most commonly practiced SWC measures (i.e., terraces and exclosures with and without terraces) were established since 1997 by the community. Many of the SWC structures constructed are fully owned by the communities. is has contributed toward ensuring their sustainability (BoANR 2014). [coded for exclosures only] In the case of exclosures without terraces, there was no interference of livestock and human practices. Besides, no other management practices such as physical structures were observed. Trees regenerate naturally and hence better vegetation cover than terraces.

• Landscape/sea scape ecosystem management: No

• Climate change impacts	Effect of Nbs on CCI	Effect measures
  Reduced soil quality	Positive	Soil erosion [positive] Soil fertility [positive] Same outcome measures for both: soil glomalin, aggregate size distribution, water stable aggregates (WSA) and aggregate-associated organic carbon. These measures were selected because they are an indicator of soil structure, functioning, stability, and resilience: “Aggregate stability is soil physical property consid- ered during restoration of degraded lands [17]. It is a measure of the ability of the soil to resist change due to environmental factors [18]. Soil organic carbon (SOC) and aggregate stability enhance vegetation growth [19]. e stability of soil aggregates in uences the water hold- ing capacity of soil and tells the susceptibility of the soil to erosion… Change in aggregate stability is an indicator of organic matter content, biological activity and nutrient cycling in soils [15] which are essential for the functioning of eco- systems… Soil glomalin forms soil aggregates and improves soil structure and stability against erosion [31, 32] as soils with stable aggregates are more resistant to erosion [33]. It is also source of active soil organic carbon [34] and contains 30–40% carbon [35]. e SOC associated with various aggregate size fractions reduces the impact of erosive forces [4] and tells the dynamics of soil organic matter… ”
  Soil erosion	Positive	Soil erosion [positive] Soil fertility [positive] Same outcome measures for both: soil glomalin, aggregate size distribution, water stable aggregates (WSA) and aggregate-associated organic carbon. These measures were selected because they are an indicator of soil structure, functioning, stability, and resilience: “Aggregate stability is soil physical property consid- ered during restoration of degraded lands [17]. It is a measure of the ability of the soil to resist change due to environmental factors [18]. Soil organic carbon (SOC) and aggregate stability enhance vegetation growth [19]. e stability of soil aggregates in uences the water hold- ing capacity of soil and tells the susceptibility of the soil to erosion… Change in aggregate stability is an indicator of organic matter content, biological activity and nutrient cycling in soils [15] which are essential for the functioning of eco- systems… Soil glomalin forms soil aggregates and improves soil structure and stability against erosion [31, 32] as soils with stable aggregates are more resistant to erosion [33]. It is also source of active soil organic carbon [34] and contains 30–40% carbon [35]. e SOC associated with various aggregate size fractions reduces the impact of erosive forces [4] and tells the dynamics of soil organic matter… ”

• Approach implemented in the field: Yes
• Specific location:

  Degua Temben district, located 50 km west of Mekelle, regional capital of Tigray region, northern Ethiopia. Geographically, it is located at 13°16′23′′–13°47′44′′ latitude and 39°3′17′′–39°24′48′′ longitude (see Fig. 1).

• Country: Ethiopia
• Habitat/Biome type: Montane/Alpine |
• Issue specific term: Not applicable
  

Evidence

• Notes on intervention effectivness: Effectiveness determined by comparing outcome measures to non-conserved communal grazing areas (acting as a control) Although some outcomes were the same between control and intervention, most were greater in the intervention (positive + no effect = positive) Mixed effectiveness compared to alternatives because for some measures, the engineered approach (stone terraces) or the hybrid (terraces + exclosures) were more effective than exclosures alone but in other measures, the reverse is true.
• Is the assessment original?: Yes
• Broadtype of intervention considered: Engineered approach(es) and other non-NbS approach(es)
• Compare effectivness?: Yes
• Compared to the non-NBS approach: Mixed
• Report greenhouse gas mitigation?: No
• Impacts on GHG: Not applicable
• Assess outcomes of the intervention on natural ecosystems: No
• Impacts for the ecosystem: Not reported
• Ecosystem measures: n/a
• Assess outcomes of the intervention on people: No
• Impacts for people: Not reported
• People measures: n/a
• Considers economic costs: No
• Economic appraisal conducted: No
• Economic appraisal described:
• Economic costs of alternative considered: No
• Compared to an alternative: Not reported

Evaluation methodology

• Type of data: Quantitative
• Is it experimental: Yes
• Experimental evalution done: In-situ/field
• Non-experimental evalution done: Not applicable
• Study is systematic: