IMPACT OF ACACIA SALIGNA ON SOIL PHYSICO-CHEMICAL PROPERTIES ALONG ALTITUDINAL GRADIENTS AT LOWER MEQI WATER SHED, SODO WOREDA, SNNPRS

Abstract

Acacia saligna is used in Ethiopia as for conservation and improving degraded soil and its nitrogen fixing ability of the tree improves soil fertility The study was conducted to evaluate Acacia saligna litter yield and its effects on soil physico chemical properties under slope gradients on degraded landscape under restoration at Lower Meqi, Sodo District, Gurage Zone, Ethiopia. To achieve this objectives, three distance treatment plots (1m, 2m and 3m) were laid under Acacia saligna trees crown and one more plot in the open area away from tree influence to compare with under crown/canopy treatment distances. Thus, these four plots in total were replicated at three slope gradients (upper, middle and lower) where the tree species was planted for degraded land reclamation, making the total treatment plots theirtysix . Litter input was collected under six years old Acacia saligna trees. Data on monthly litter yield was collected under 9 Acacia saligna trees located in three altitudinal gradients for 6 consecutive months. Litter collected on monthly bases was weighed for fresh and air-dry weight at each collection months. Adendirometeric parameter for A.saligna trees as diameter, crown radius, crown spreade, total height and DBH) mean and standard deviation were computed. A composite soil samples were collected from 20 cm soil depthusing soil auger. These samples were collected from all compass directions of the tree for the respective distances i.e., 1m, 2m and 3m from the tree bole and the control plot away from tree influence. A total of 36 soils composite samples under 9 Acacia trees and 3 open areas away from tree influence along the altitudinal gradient were prepared for soil physicochemical properties and analyzed using standard procedures. The results from T-test between the mean of fresh and dry litter weight of Acacia saligna revealed that there were statistically significant differences at p<0.05 for the months. The highest total litter fall fresh mass (932.2g) was recorded in the months of June (2022). whereas the lowest total fresh mass (205.2g) was obtained in January (2022). The soil texture, bulk density and pH, OC, TN, Av.P, OM, CEC, Ca+2, Mg+2, K+, and Na+ were significantly (p ≤0.05) affected by distance and slope gradients. The mean values of sand, soil texture , pH, OC, OM, TN, CEC, Ca+2, Mg+2, K+, and Na+ were higher in distances under the tree crown as compared to the control site (none A. saligna area). In order to increase soil physicochemical properties, extensive Acacia saligna plantation with integrated soil management practice is recommended for application of the restoration practice.