Status of Selected Physicochemical Properties of Soils Under Long Term Sugarcane Cultivation Fields at Wonji-Shoa Sugar Estate

A declining trend in per hectare yield of sugarcane in Wonji-Shoa Sugar Estate is being observed due to altering of soil physicochemical properties resulted from long term sugarcane cultivation. Cognizant of this fact, a study was conducted in 2017at Wonji-Shoa Sugar Estate with the objective of determining the effects of more than 62 years of sugarcane cultivation on the physicochemical properties of soil. In order to achieve this objective disturbed and undisturbed soil samples were collected from 0-30 and 30-60 cm layers of selected cultivated and uncultivated light and heavy soils for laboratory analysis. Results of the study indicated that long term cultivation of sugarcane at the same depth and low soil organic matter content of cultivated fields induced soil compaction and consequently highest bulk density was recorded in subsoil layer of cultivated than uncultivated land. The bulk density and total porosity values were out of ranges recommended for optimum sugarcane cultivation and suggest the existence of some degree of compaction. The finding further showed that the pH of study area soils is out of the normal pH range for sugarcane plant growth. The soil organic carbon, total nitrogen content and available phosphorus concentration of soils under both land uses of all soils was found within low range. Therefore, based on the result of the study it can be concluded that under condition of strong base soil pH of study area the availability of essential nutrients are critically affected. This indicates that the strong pH values at Wonji-Shoa Estate require more attention. Moreover, the low levels of organic carbon, total nitrogen, and available P contents under both cultivated and uncultivated soils indicated that soil fertility is among the constraints for sustainable sugarcane production in the estate. Based on the findings and conclusions of this study one can recommend that to maintain sustainability of sugarcane production in the estate soil management practices that can protect as well as ameliorate soil compaction, increase soil organic carbon, total nitrogen, soil available P and that can decrease soil pH are important. Nevertheless, in order to give conclusive recommendation further research studies are needed for more soil management units in the estate.