Participatory Evaluation of Different Multipurpose Grass Species for Graded Soil Bund Stabilization in Gimbo District, South West Ethiopia

摘要

Soil erosion is one of the biggest threats to agricultural productivity in South West Ethiopia. Steep slopes, high rainfall and fragile ecosystem characterize these production systems. To reverse this trend, integration of physical and biological soil and water conservation measures is very important. This study was conducted to evaluate different multi-purpose grass species as soil bund stabilizers. Graded soil bunds were constructed on selected eight farmers’ farmland and five grass stabilizers were grown on the embankment of the bund. Five soil bund stabilizers are i) vetiver grass, ii) elephant grass, iii) desho grass, iv) rodes grass, and v) guinea grass. Data on the survival, biomass, and frequency of harvest of those stabilizers on the soil bund were collected. Soil samples were also taken before and after the establishment of experiment. Furthermore, performance criteria were established through group discussions with farmers, and stabilizer (grass) performance was later evaluated according to these criteria. The criteria were weighted using pair-wise ranking and scored with a scale of 1 (not good) to 5 (best) based on each criterion. Desho grass was found to survive and establish on the embankment of soil bund earlier (10 - 25 days) than the others and followed by elephant and vetiver grass. Furthermore, desho grass was observed to have higher green biomass and frequency of harvest compared to elephant and vetiver grasses. Results of soil chemical properties (Soil N, soil P, Soil K, % OC, pH and CEC) revealed no significant differences in amount of total N, and available P and K between the soils of “before” and “after” the establishment of integrated soil bund. Based on the overall weighted scores obtained using pairwise ranking approach, desho grass ( P. pedicelluatum ) was found to be the overall most desirable stabilizers and followed by elephant ( Pennisetum purpureum ) and vetiver ( Vetiverial zizanioides ) grasses in the study area. Therefore, there is a need to develop SWC practices with stabilizers such as desho and elephant grasses.