Assessment Of The Effects Of Eucalyptus Globules On Selected Soil Physicochemical Properties And Crop Production: The Cases Of South West Shewa Zone, Dawo District

Abstract

In most developing countries, including Ethiopia, soil quality is declining because of miss use of land. The miss use includes plantation of trees in croplands without due attention to the species selection. This study was carried out to assess the effect of Eucalyptus globules plantation on selected soil physicochemical properties a n d crop production in Dawo Districts. To undertake this study, four experimental plots of 10m × 10m each were used together with survey questionnaires from 398 participants. Each experimental plot was purposefully selected from cultivated land adjacent to E. globulus plantation – under the canopy and two meter from the canopy three sites in four kebeles with a total of 24 soil samples collected randomly. In each of these sites, two undisturbed soil samples were also taken for bulk density (BD) determination. All soil samples were collected at a depth of 0-30 cm using soil auger. The soil analysis data and survey response were analyzed using SPSS version 24 statistical software. The results indicated that Eucalyptus plantation significantly affected soil moisture content. Soil BD under E.glubules sp plantation. Moreover, the results revealed that cultivation of E. globulus tree was, leading to a significant decline in soil total nitrogen (0.09 %) and soil total organic carbon (0.83%) concentrations compared to the adjacent crop fields. Decomposition of the litter from Eucalyptus globulus spp. also caused increase in concentration of soil exchangeable acidity (0.32 c mol(+) kg-1 ), exchangeable sodium (0.52 cmol(+)kg-1 ), available phosphorus (23.2 mg kg-1 ), rendering it unavailable for plant use. However, in the study, no significant differences were found between cultivated land and soils sampled under E. globulus tree in terms of soil exchangeable Mg+2, Ca+2 and K+ , cation exchange capacity (CEC) and effective CEC. The concentrations of the exchangeable Mg+2 , Ca+2 and K + and effective CEC were low, which possibly contributed to the increased soil acidity. Furthermore, the concentrations of total N (1.05 %) and total P (0.15 %) were lower under Eucalyptus globulus canopy compared with the cultivated land where concentrations of total N and total P were 2.11 and 0.17 %, respectively. The study demonstrated that sole cultivation to Eucalyptus spp. had the tendency to lower soil fertility and so it is advisable to supplement crop production under the trees with good agronomic practices such as nitrogenous and phosphate fertilizer application to replenish loss of the essential soil nutrients such as N and P associated with Eucalyptus spp. planting and also to ensure sustainability ofon the soil resources.