Adoption and Effect of Vetiver Grass (Vetiveria zizanioides) on soil Erosion in Somodo Watershed, South-Western Ethiopia

摘要

Soil erosion is an important cause of land degradation and consequent to soil fertility which reduces land productivity and production. This problem aggravates in developing countries like Ethiopia. To minimize this challenge, soil and water conservation with proper design is the first choice. The aim of this study was to assess the adoption and effect of Vetiver grass on soil erosion in Somodo watershed. Community mobiliz ation was used to implement Vetiver grass on farm lands as bund stabilization and grass strip. Accordingly, more than 45 km (20%) of the watershed was covered by Vetiver grass on soil bund as bund stabilizing measure. The hedge was fully established within two years and formed averagely 36 cm raised terrace. The result of the study showed that within two years period about 36 cm soil was accumulated above the hedgerow. From mean annual soil deposition and average bulk density of the watershed, the mean annual soil loss was recorded 20.88 ton ha ﹣) 1) ·year ﹣) 1) in the absence of Vetiver hedge row as erosion barrier. In addition, field slope was reduced on average by 2.5% due to soil accumulated above Vetiver hedgerow. And phosphorus availability was found higher on the above hedgerow than below the hedge row while, exchangeable acidity was found less above the hedgerow than below the Vetiver hedgerow in the watershed which implies soil fertility improvement. The study recommends Vetiver hedgerow as an immediate mitigation measure for soil erosion on hill slopes and farm lands which can be implemented through community mobilization. Further study on how the Vetiver hedgerow improves phosphorus availability and decreases exchangeable acidity is also highly recommended.