Soil Acidity in Ethiopia: Its Causes, Effects on Crop Production and Management Experiences So Far- Review

Abstract

Soil acidity is a serious chemical problem that limits agricultural productivity in most of the highlands of Ethiopia as well as in the western part of the country. These acidic soils, which cover an estimated 41% of the arable land in Ethiopia, are inherently infertile and exhibit aluminium (Al) or manganese (Mn) toxicity, which are generally considered to be the major limiting factor for plant growth in acidic soils. The major factors leading to acid soils in western Ethiopia include erosion of topsoil by heavy rains and high temperatures, which increase the greatest loss of organic matter and leaching of exchangeable basic cations (Ca 2+ , Mg 2+ , Na + and K + ). Organic matter can be easily degraded and lost through conventional land clearing practices such as burning and direct sun and rain exposure, which is exacerbated by improper agricultural practices. If these soils are not properly managed after clearing, they can quickly lose much of their original fertility and beneficial physical as well as biological properties. It has been suggested that maintaining production on these soils requires an effort far beyond the means of poor farmers. Because low pH affects the availability of nutrients, especially phosphorus and other macronutrients, correcting low pH through liming and/or the application of organic matter (such as compost and vermicompost) is critical to the sustainable management of these acidic soils. The recently introduced technology of organic soil amendment with vermicompost has proven to be a potential resource to significantly improve soil fertility and soil health in various soil types around the globe. Therefore, farmers should be encouraged to increase the productivity of acidic soils through organic amendments such as compost/vermicompost. Vermicomposting, which is still very young and rarely practiced by farmers, should be supported and strengthened by more research and extension than we currently have to produce high quality vermicompost to amend acidic soils of Ethiopia and restore soil life.