Assessment of the Severity of Acid Saturations on Soils Collected from Cultivated Lands of East Wollega Zone, Ethiopia

Abstract

The study was conducted during 2014 on acidic soils collected from agricultural lands of selected Districts of East Wollega Zone and its aim was to determine the status, extents and rating of the level acid saturation percentages of the soils of agricultural lands of the study area. Field observation and soil surveys on acidic soils of agricultural lands of the study areas were carried out and then delineated and dug on different landscape positions. Representative composite soil samples were collected from agricultural fields of the soil surfaces (0-20 cm) depth and analyzed at Nekemte and Holleta Soil Research Center Laboratory for soil pH, Aluminum saturation, exchangeable hydrogen, exchangeable acids and bases as well as soil available and total phosphorus. Laboratory analysis was determined based up on their corresponding standard procedures. Data generated were subjected to analysis of variance using SAS software version, 9. The results of the study revealed that the soils in the entire agricultural fields of the studied districts of East Wollega Zone are ranged the soil pH(H₂O) from 4.63 to 6.01 which rated as very strongly acidic at Wayu Tuka to moderately acidic at Gida Ayana District. Highest (71.85%) and lowest (17.45%) PAS were recorded in the soils collected from Wayu Tuka and Diga Districts, respectively. The inverse relationship of exchangeable acidity and PAS with PBS may be attributed to intensive cultivation which leads to the higher exchangeable acidity content in soils collected from Wayu Tuka District than the remaining agricultural fields. The status of soil acidity in almost all the agricultural field of present study are beyond acidity tolerance limit of acid sensitive crops in the area. Therefore, due attention must be given to minimize the severity of Al toxicity of the soils with high PAS in the area, to reinstate intensively cultivated agricultural fields by improving the soil properties through crop rotation, returning crop residues to the fields and by using different amendment options such as agricultural liming materials.