Farmer-science-based soil degradation metrics guide prioritization of catchment-tailored control measures

Abstract

Locally valid and up-to-date soil degradation surveys that account for the spatial variability and the dynamic nature of degradation processes within environmentally diverse catchments are scant. Failure to understand local priorities and involve land users in the assessment of soil degradation and restoration initiatives however might compromise the adoption of effective soil and water conservation (SWC) measures. This paper presents farmer-science-based metrics (FSBM) of soil degradation status for locally perceived degradation processes, thereby using socio-economically relevant criteria and permitting a standardized comparison of their status across various decision-making entities. The approach was tested in the low-, mid-and highland agro-ecological zones (AEZs) in two catchments of the Lake Abaya-Chamo Basin, Ethiopia. After defining land users' relevant classes of land degradation degree, extent and impact, the soil degradation status perceived by 384 household heads was collected during face-to-face interviews. The respondents' evaluation of soil degradation status was translated into numerical scores (FSBM) and shown on radar diagrams, stratified by AEZ and catchment. Our findings demonstrate that the adopted FSBM offered spatially explicit information on the three dimensions of degradation status by soil degradation type. Disentangling degree, extent and impact revealed the diversified occurrence of the soil degradation processes between and within similar AEZs of the catchments. Natural and human factors were pinpointed as causes, while assessment of consequences revealed spill-over effects of soil erosion taking place in midland AEZs into the lowlands. Biophysical aspects, socio-economic characteristics and proximity to training centers played significant roles in the respondents’ perceptions. Despite the subjectivity associated with FSBM, our findings demonstrate that involving land users in the assessment of soil degradation provided a comprehensive overview of soil degradation status and current bottlenecks in its combat.