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Universität für Bodenkultur Wien (2007)

Evaluation of selected indigenous and exotic tree and shrub species for soil fertility improvement and fodder production in the highland areas of western Shewa, Ethiopia

Kindu Mekonnen Tegegne

Titre : Evaluation of selected indigenous and exotic tree and shrub species for soil fertility improvement and fodder production in the highland areas of western Shewa, Ethiopia

Auteur : Kindu Mekonnen Tegegne

Akad. Grad : Dr. nat. techn. Wien, Univ. für Bodenkultur, Diss., 2007

Université de soutenance : Universität für Bodenkultur Wien | Department für Wald- und Bodenwissenschaften | Institut für Waldökologie

Résumé
Selected tree and shrub species were evaluated for soil fertility improvement and fodder production on three sites in the highlands of western Shewa, Ethiopia. The indigenous species included were Acacia abyssinica, Buddleja polystachya, Cordia africana, Dombeya torrida, Hagenia abyssinica and Senecio gigas. Exotic species included were Acacia decurrens, A. melanoxlon, A. mearnsii, A. saligna, Chamaecytisus palmensis, C. proliferus, Eucalyptus globulus, E. camaldulensis, Grevillea robusta and Sesbania sesban. Soil samples were collected at different depths and horizontal positions from the bases of the trees to analyze pH, organic C, total N, available P, exchangeable bases and some micronutrients. Similarly, plant samples were collected to determine macronutrients, micronutrients, fodder nutritional parameters and other indicators for green biomass quality. In Luvisol areas (> 2900 m.a.s.l), the foliage N content in B. polystachya, D. torrida, H. abyssinica and S. gigas was comparable with C. palmensis. The foliage, flower bud and stem P content in C. palmensis was low as compared to B. polystachya, D. torrida, H. abyssinica and S. gigas. A higher foliage, flower bud and stem K content was found in the S. gigas. The foliage and flower bud soluble phenolic content in C. palmensis was the lowest. The in vitro dry matter digestibility of the foliage and flower bud from H. abyssinica and C. palmensis was reasonably high. The soil organic C and total N content under H. abyssinica, S. gigas, C. palmensis and D. torrida were comparable in the top 0-15 cm depth. In comparison with below the other species, the soil under H. abyssinica and S. gigas had a high content of exchangeable K at the 0-15 cm depth of the 75, 150 and 225 cm horizontal positions. The contents of organic C, total N, available P, exchangeable K, Ca and Mg showed a decreasing pattern from 0-15 to 30-50 cm soil depths and from the 75 to the 150 and 225 cm horizontal positions. In Vertisol areas (2200 m.a.s.l), A. decurrens, A. mearnsii and E. globulus had attained the highest height growth 64 months after planting as compared to A. abyssinica, A. melanoxlon, C. africana, A. saligna and S. sesban. Acacia mearnsii and A. saligna had produced high biomass 40 and 64 months after planting. Sesbania sesban had high N and P concentrations in its foliage and stems at 12 and 40 months. Total N under A. abyssinica, A. saligna and S. sesban was slightly greater at 40 months than 12 months. In Nitisol areas (2400 m.a.s.l), G. robusta exhibited slow height growth and wood production as compared to A. decurrens, C. palmensis, C. proliferus, E. globulus and E. camaldulensis. Acacia decurrens provided the highest mean dry biomass at 64 months. Foliar N levels in A. decurrens, C. palmensis and C. proliferus were significantly higher than H. abyssinica, G. robusta, E. globulus and E. camaldulensis and. Hagenia abyssinica had higher K levels in the foliage and wood. Eucalyptus species tended to deplete soil fertility whereas C. palmensis and C. proliferus improved soil fertility. The foliage and flower bud of H. abyssinica, B. polystachya, D. torrida and C. palmensis can be used as sources of fodder with a proper feeding management scheme. Hagenia abyssinica, S. gigas and C. palmensis can play a soil management role in the farmlands of high altitude areas, where soil erosion and nutrient depletion are critical problems. Acacia mearnsii and A. saligna are superior tree species on Vertisols in terms of biomass production whereas Chamaecytisus species and A. decurrens can be short-term options for soil fertility improvement and sources of fuel wood in Nitisol areas

Mots clé : Äthiopien / Bodenfruchtbarkeit / Bodenmelioration / Biomasse / heimische Pflanzen — Soil fertility / Ethiopia / amelioration / biomass / indigenous plants

Présentation : Österreichische Dissertationsdatenbank

Page publiée le 3 mars 2008, mise à jour le 13 mars 2019