EFFECT OF SLOPE GRADIENT AND MANAGEMENT PRACTICES IN SELECTED SOIL CHEMICAL AND PHYSICAL PROPERTIES OF DAWJA WATERSHED, EAST GOJJAM ZONE

Abstract

Information on the Effect of Slope Gradient and Management Practices in soil chemical and physical properties is key for predicting the relative response of soils to application of fertilizers and putting forward appropriate management practices. The present study was, thus, conducted to assess the selected chemical and physical properties of the soils as affected by slope gradient and management practices at the Dawja Watershed in Enebse Sar Midir District of East Gojjam Zone, Ethiopia. A total of 21 composite soil samples were collected from the 0-20 cm soil depth of 7 land units, identified based on their slope and management practices, for analysis of selected physicochemical properties. Except available phosphorus (P), all the soil parameters were significantly (P < 0.05) affected by differences in land units. The textural class of the soils varied between sandy clay loam and sandy clay. The bulk density of the soils under the different land units ranged between 1.32 and 1.41 g cm-3 and the total porosity varied from 46.66 to 50.10%. The pH of the soils ranged from 5.7 in soils of strongly sloping land unit (LU 1) to 6.8 in soils of gently sloping land unit (LU 2). The organic matter content of the soils was generally low and ranged between 1.17% in strongly sloping cultivated land unit (LU 1) to 2.46% in grazing land unit (LU 4) soils. The total nitrogen content of the soils ranged from 0.13 to 0.19%. Available P (Olsen) was generally high in all the land units and ranged between 17.92 to 23.02 mg kg-1. The available K of the soils under different land units was between 141.51 mg kg-1 and 239.78 mg kg-1. The results further showed that the soils were generally rich in exchangeable basic cations (Ca, Mg, K and Na) with CEC ranged between 18.13 cmol(+) kg-1 in soils of strongly sloping cultivated land unit (LU 3) to 41.87 cmol(+) kg-1 in soils of gently sloping land unit (LU 2). The percent base saturation of the soils varied between 62.30 and 92.20%. The extractable micronutrients (Fe, Mn, Zn and Cu) of the soils were above their respective critical levels, which indicate that they are not limiting crop production at the moment. In general, soils of the study area are good in their selected physical and chemical properties for plant growth except organic matter and total nitrogen. Therefore, the soil fertility management in the study area should focus on scenarios that could improve the effects of slope gradient and soil management practices on the organic matter and nitrogen levels of the soils for improving crop production on a sustainable basis.