Abstract
The study aimed to evaluate the soil chemical properties dynamics under different land-use systems and soil depths in the central highlands of Ethiopia. The land-use systems included natural forest, four exotic tree plantation species (Eucalyptus globules, Cupressus lusitanica, Grevillea robusta, and Pinus patula), grassland, grazing land, and cropland. The systematic sampling design was used to collect soil samples from 96 main quadrats (20 m x 20 m area each) along 32 transect lines. The soil samples were collected with soil auger from two depth of topsoil (0 – 20 cm) and subsoil (20 – 40 cm) layers with five sub-quadrats (1m x 1m) replication within a main quadrat by arranging four at each corner and one at center. The analysis of variance for the majority of soil chemical properties of OC, TN, Avial. P, soil pH, EC, CEC, and exchangeable bases (Ca, Mg, K, Na) were showed that significant variations among land-use systems (P<0.0001). The highest mean values of OC (3.49 % DM), TN (0.31% DM) , Available (31.52 mg/kg of soil ), CEC (33.63 meq/100gm soil), Exch. Ca (17.13 cmol(+)/kg soil), Exch. Mg (5.37 cmol(+)/kg soil), and Exch. K ( 3.60 cmol(+)/kg soil) were observed under natural forest than others of land-use systems. The results also showed that the lowest mean values of OC, TN, soil pH, CEC, Exch. (Ca, K, and Na) were recorded under cropland. The overall mean values of OC, TN, Avail. P, CEC, and Exch. (Mg, Ca, K, Na) were higher at topsoil than subsoil layer except for soil pH and EC. In general, the majority of soil chemical properties under cropland and Eucalyptus globulus plantation forest were poorer than the soils subjected to other land-use systems.