ASSESSEMENT OF STATUS OF SOIL ACIDITY UNDER DIFFERENT LAND USE TYPES AND SLOPE GRADIENTS: THE CASE OF WEST AZERNET BERBERE DISTRICT, SOUTHERN ETHIOPIA

Abstract

The general purpose of the study was to evaluate the effects of land use types; slope gradient and their interaction on soil acidity and selected physico-chemical properties in West Azernet Berber Woreda. The experiment was taken as the randomized complete block design (RCBD) with two factors and total of 27 composite samples were taken. For data analysis, general linear model procedure of SAS version 9.4 was used.Three land uses (natural forest, grazing and cultivated land), and three slope gradients (10-15%, 5-10% and 2-5%) in three replications were considered for this study. Totally 27 composite soil samples were collected from cultivated, forest and grazing lands and slope gradients with three replications for laboratory analysis. Results indicated that the highest mean value of sand was recorded in grazing land and highest mean value of silt and clay were recorded under forest land, cultivated lands and upper slope classes respectively. Soils were strongly acidic (pH =5.2-5.4), whereas natural forest land uses and lower slope classes were moderately acidic2 (pH =5.9-6.0). The total porosity, bulk density and PH, Av.P, OM, CEC,Ca+2, Mg+2 K+, Na+, were significantly (p ≤ 0.001) affected by land use types and slope gradients .Percent base saturation Total nitrogen and except silt, particle size distribution were significantly (P ≤ 0.05) affected by land use typesand slope classes . The mean values of sand ,total porosity, pH, OM, TN, CEC, Ca+2, Mg+2, K+, Na+ and PBS were higher in forest and lower slope classes as compared with grazing , cultivated lands and in 10-15% and 5-10% slope classes respectively. The exchangeable acidity and exchangeable Al were significantly (P≤0.05) affected by under cultivated land and grazing lands and upper slope classes. Generally, land use types and slope gradient have significant effect on their interaction soil acidity and selected physic-chemical properties of soil. Therefore, in order to reduce soil acidity problem, minimize intensive cultivation, over grazing, liming and integrated soil acidity management practice is recommended for study area and further study should be investigated on the rest soil nutrients.