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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/1847

Advisors: Dr. Fisseha Itanna
Keywords: middle Awash
soil quality
land use
land use change
SOC change
Copyright: 2007
Date Added: 20-Dec-2008
Publisher: Addis Ababa University
Abstract: The Middle Awash Valley has been the development scene of agriculture and industry since early 1960s. This has changed the centuries old land use and land management strategy and the intensity at which natu-ral resources exploited. This study was carried out in Fantale district, upper middle Awash valley. It was aimed at determining soil organic carbon (SOC) level and associated soil attributes as influenced by land use. Pastoral, agropastoral and conservation sites were considered for the study. In both community and conservation sites, three major land uses (from cropland, grazing land, shrub land and woodland) were considered for soil sample collection based on their importance and extent of practice. Pertinent socioeco-nomic data were collected from local community with emphasis on long-term land use and land manage-ment practices. The study results indicate that SOC and TN stock cover wider range. SOC in the top 20cm depth ranges from as low as 3.29 kg m-2 in SHL to as high as 6.03 kg m-2 in WL. On the other hand, soil TN ranges from as low as 0.17 kg m-2 in GL to 0.43 kg m-2 in WL. GL soils had significantly (P < 0.05) low soil TN than other land uses and was also associated with least soil attributes considered. Site wise, many of soil attributes (OC, TN, CEC and some others) follow the following gradient: Qobbo (agropastoral site) < Dhebiti (pastoral site) < ANP (Conservation site). Land use conversion has resulted in differing rate and direction of change in SOC and TN stock. Short time scale GL conversion to CL has caused a total loss of 6 % (6 % per year) of SOC while the change in TN stock was insignificant. On the other hand, SHL cultiva-tion has increased both SOC (17.63 % [2.2 % per year]) and TN (5 % [0.63 % per year]). This is an indi-cation of the negative consequence of shrub invasion on SOC and associated soil properties and possibility to recover lost SOC through appropriate land use and land management. Crop land expansion and inva-sion of former grass land by shrub may be the consequences of failure of community lands to support the former traditional production system and change in land use intensity, respectively. Change in land use and land use intensity was one of the ways in which the community reacts to production challenges. The traditional economic activity (pastoralism) was no more functioning as before as it needs large land ex-panse. Therefore, change in land use and land use intensity may be the way local communities respond to production constraints in the future, too. The crop lands and shrub lands were, on the other hand, associ-ated with low SOC and other soil attributes (except TN in SHL). In general, the biomass input to soil sys-tem may be of low quality in the study area. There were strong positive association among SOC, TN and CEC. Land use and land tenure were under actively changing state. Land privatization in the form of largely CL and to some extent GL, both at the expense of productive communal GL, was underway with concomitant negative effect on the extent and productivity of remaining GL. In addition to total soil OC quantification, there is a strong need to determine the soil OC fractions that respond more to land use and land management as well as OC input/output balance to use this soil property as indicator of ecological relationship among economic activities and harvest various benefits associated with this soil property.
Description: A Thesis Presented to School of Graduate Studies in Partial fulfillment of the Requirement for the Degree of Masters of Science in Environmental Science Department of Environmental Science
URI: http://hdl.handle.net/123456789/1848
Appears in:Thesis - Environmental Sciences
Thesis - Environmental Sciences

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