Long Term Effects of Cultivation on Physicochemical Properties of Soils at Metahara Sugar Estate

摘要

In Ethiopia, where sugarcane has been cultivated for over 47 years, changes in soil physicochemicalproperties are expected to occur albeit information on the extent of change is scanty. A study was conductedin 2015 at Metahara Sugar Estate with the objective of assessing the status of selected soil properties underlong term mechanized sugarcane cultivation. Disturbed composite and undisturbed soil samples from 0-30 and30-60 cm layers of selected cultivated and uncultivated light and heavy soil management unit groups (SMUGs)at Metahara were collected for laboratory analysis of selected soil properties. Results of the study indicatedthat sand and clay content, bulk density, total porosity, pH, soil organic carbon, total nitrogen, and availableP content were significantly (P < 0.05) affected by land use. With some exceptions, clay content of thecultivated lands was higher than that of the adjacent uncultivated lands, while the reverse was true for bulkdensity. The pH of the uncultivated lands was higher than the pH of the cultivated lands, whilst organic carbon,total nitrogen, and available P contents were higher in the cultivated than in the uncultivated lands of eachSMUG. The measured soil properties also showed some variations with soil depth. Bulk density increased withsoil depth in the cultivated and decreased with depth in the uncultivated soils of each SMUG. The bulk densityvalues for a clay texture for most of the studied soils were higher than the critical values (1.22 to 1.35 g cm 3)recommended for successful sugarcane production indicating the prevalence of soil compaction. The pH of thetwo land uses also ranged between 8.24-8.35, which was strongly alkaline. Organic carbon (1.07 to 1.60%), totalnitrogen (< 0.12%), and available P (3.08-4.25 mg kg 1) were also in the range those are not adequate forsugarcane cultivation in the estate. Overall, the measured soil properties indicate that the management practicesthe estate has been implementing were not adequate to sustain sugarcane production on a profitable basis and,thus, require revisiting the practices.