Evaluation of Effect of land use types on Selected Soil Physico-chemical Properties in Itang-Kir area of Gambella region, Ethiopia

Abstract

Changes in land use type and soil management can have a marked effect on soil physical and chemical properties. This study was conducted at Itang-kir area which is located in Itang special district of Gambella Regional State, Ethiopia. The aim of the study was to investigate the effect of land use types on selected physico-chemical properties of the soils. Cultivated and grazing land types were considered for the study. Cultivated and grazing land use types were adjoining to each other. Based on soil texture and slope class four land units were recognized from both land use types (IK1, IK2, IK3 and IK4).A total of eighteen composite soil samples were collected from both land use types from 0-20cm soil depth for laboratory analysis. The results of the experiment revealed that both land use types had a clay, sandy clay loam, sandy clay and sandy loam texture in all land units. The highest bulk density (1.39gcm^-3) was observed in IK4 of grazing land and the lowest (1.24gcm^-3) was observed on IK1 of cultivated land. The highest soil bulk density recorded in grazing land might be resulted from livestock compaction. Soil pH (H₂O) rated as neutral to moderately alkaline for cultivated and neutral to strongly alkaline for grazing land units. For soil organic matter content the highest (4.82%) and the lowest (2.10%) were recorded in grazing land whereas the highest (3.82%) and the lowest (1.8%) were recorded in cultivated land. Total nitrogen ranged from 0.29% - 0.10% for grazing land and from 0.24% - 0.10% for cultivated land. Available P recorded in grazing land ranged from 61.29 to 16.18 and 58.95 to 15.25 mg kg^-1in cultivated land use type. Available P status of the two land use types is from high to very high. The high available P content of the soil may be due to parent material and soil reaction. Exchangeable bases, cation exchange capacity, percent base saturation and extractable micronutrient cations (Fe, Mn, Zn and Cu) were also higher in grazing land use compared to cultivated land. The concentration of the basic cations in the soils’ exchange sites was in the order of Ca > Mg > K > Na. The highest and the lowest mean values of CEC were 52.27 and 23.20cmolc kg^-1in grazing land  and  44.08 and 22.53 cmolc kg^-1 on cultivated land for land units IK1 and IK4, respectively. Therefore both land use types had high CEC except on land unit IK4 which revealed medium CEC value. While the contents of extractable micronutrients were relatively higher in the grazing as compared to cultivated land use this could be rated sufficient for Fe, adequate for Mn and Zn, whereas marginal to deficient level for Cu for both land use types. From this study one can conclude that crop cultivation has led to more essential nutrients removal compared to livestock and adversely affect soil chemical properties. Therefore, integrated soil fertility management that maintain and improve physical, chemical and biological properties of soil should be implemented on cultivation land types in order to optimize and sustain crop production.

Keywords: land use type, Soil chemical properties, land units