ASSESSMENT OF SOIL ACIDITY AND LIME REQUIREMENTS IN THE HARAM WATERSHED, GETA DISTRICT, GURAGE, ZONE CENTRAL ETHIOPIA

Abstract

Soil acidity is one of the main factors that limit agricultural productivity in many parts of the Ethiopia. Study was conducted at Gurage zone Geta District on acidic soils collected from dominant crop fields of the three selected kebeles. The selected kebeles Agata, Quante and Henbeyate were selected based on the severity of soil acidity . Field observation and general visual reconnaissance survey of the area was carried out .Representative composite soil samples were collected from at (0-20cm) depth. Selected soil physicochemical were analyzed following the standard procedures and lime incubation study was carried out to determine amount of lime required to neutralize acidity of the soil to the optimum pH 6.0 to 6.5. Results of the study revealed that the textural class of the area was loam. pH (H2O) ranged from 5 to 5.16 which rated as very strongly acidic to strongly acidic in reaction. The mean values of CEC, PBS, AP, and OC were low and ranged from 10.54-10.66, 35.97-36.46, 8.99-10.03 and 1.13-1.16 respectively. This low amount may be due to the low additions of organic matters or litters deposition in the agricultural croplands, and continuous removal of basic cations by crops, intensive cultivation that enhanced leaching of basic cations, and removal of exchangeable bases by rill, and sheet erosion. Soil acidity due to aluminum toxicity is a common problem for plant growth for barley and wheat, and causes significant losses of crop production, in all the study areas. The results showed that incubation of soil using lime/ CaCo3 raised soil pH from very strongly acidic (5) to near optimum (pH of 6 to 6.5), in suitable range for most crops production. Based on results of incubation study, 10.26 tha-1 of lime was required for soil of Agata, 10.86 tha-1 of lime for soil of Quante and 8.64 tha-1 lime for soil of Henbeyate kebeles required to be applied to raise soil pH to the values of 6 to 6.5.