CHARACTERIZATION AND CLASSIFICATION OF SALT AFFECTED SOILS OF AMBO-COBA AREA UNDER GOLINA WATERSHED IN RAYA KOBO VALLEY, AMHARA REGION, ETHIOPIA

Abstract

It is known that all soils contain a certain amount of soluble salts and exchangeable sodium, magnesium, potassium, and calcium. However, when the concentration of either of them is excess, it will interfere with many soil processes including plant growth and the effects depend on the degree of concentration and type of plant. It is, therefore, with this understanding that a study was conducted with the objective to classify and characterize the salt affected soils of Ambo-coba in Golina watershed at Raya Kobo Valley, North Wollo Zone of Ethiopia. To conduct this activity, two profiles excavated, and one from irrigated and the other from one irrigated and those were excavated from the irrigated and non irrigated fields. Twenty soil samples were taken from the two soil profiles at 20 cm depth intervals in two meter profile depths. The samples were analyzed for some chemical properties such as soil pH, soluble cations and anions, soluble salts (electrical conductivity, EC), and exchangeable cations (Ca, Mg, Na, K), total nitrogen, organic carbon, and available phosphorus, exchangeable sodium percentage, sodium absorption ratio and physical characteristics of the soil like soil color, texture, bulk density, and soil porosity. According to the results of the analysis, the soils of irrigated and non irrigated soil profiles had pH of 7.6 to 8.8 and 7.4 to 8.5, electrical conductivity of 1.3 to 14 ds/m and 3.1 to 9.7 ds/m, organic carbon of 0.3 to 1.2% and 0.4 to 1.5%, total nitrogen of 0.11 to 0.35% and 0.09 to 0.27%, available phosphorus of 24 to 41.4 mg/kg and 25 to 46.5 mg/kg, and cation exchange capacity of 50.3 to 65.5 cmo l(+)/kg of soil and 48.7 to 57.2 cmol (+)/kg of soil, respectively. The distribution of exchangeable calcium showed inconsistency in the irrigated farmland soil profile. In general, considering the top layers of the soils of both sites (as they are responsible for agricultural purposes) taking in to account their EC, ESP, and pH values. The soils can be classified as saline and saline sodic soil for the irrigated and non irrigated farms respectively.