CHARACTERISTICS AND CLASSIFICATION OF SOILS OF GORA DAGEor FOREST, SOUTH WELO IDGHLANDS, ETHIOPIA

Abstract

The soils of the slopes of the South Welo highlands have been
either intensively cultivated or overgrazed and eroded. As a result there are few sites where undisturbed soils exist for use as a reference against which the impacts of land use can be evaluated. The Gora Daget forest on a very steep slope located close to Dessie town provides one of these rare opportunities for the type of investigation. Three pairs of representative soil profiles that formed under this indigenous mixed juniperous forest were investigated to establish the soil characteristics and identify the grouping within the FA~/UNESCO classification system. The depths of the soils ranged from less than 30 cm to slightly more than a meter. The solum in aU soil types showed very little horizon differentiation and comprised of only Ah horizon, where it is shallower, and Ah and AC horizons where it is deeper. The Ah co]our is invariably dark brown (10YR2f2) while the AC is black (IOn.2!!). The crumb structure and the loam texture typifying the surface soils changes very little with depth. The main minerals constituting the clay fraction were mica, morderite and sepiolite while those comprising the skeletal fraction were pyroxenes, anorthoclase, plagioclase, morderite, quartz, and magnetite. The organk carbon and total nitrogen are generally high but available phosphorus is low. The pH is within a range suitable to most plants while both the CEC and base saturation values registered for the soils were high. The A-horizons were moUic and the soil unUs were identified as Mollie Leptosols and Mollie Phaeozem.s. All the soils show€',o ~ransitional characteristics with Andooois necessitating their as Andi-mollic Leptosob 8.A'1d Andi-mollic Phaeozems.