Effect of Slope Position and Land-Use Changes to Bio- Physical Soil Properties in Nakasongola Pastoral Rangeland Areas, Central Uganda

Abstract

Land degradation, which includes degradation of vegetation cover, soil degradation and nutrient depletion, is a major ecological problem in Uganda. It is estimated that fertile top soil is lost at a rate of one billion cubic meters per year, resulting in massive environmental degradation and constituting a serious threat to sustainable agriculture and forestry (Yost and Eswaran, 1990). Forests and the benefits they provide in the form of wood, food, income, and watershed protection have an important and critical role in enabling people to secure a stable and adequate food supply. Deforestation and land degradation, however, are impairing the capacity of forests and the land to contribute to food security, and to provide other benefits, such as fuel wood and fodder in Uganda (Siriri et al., 2000). Ugandan environmental issues are causing a great concern because the expansion rate of such major problems as drought, desertification, water pollution, is reaching an alarming stage (NEMA, 2001). In Nakasongola district, the presence of steep slopes subject to cultivation since many years, has led to serious soil erosion. The lag in agricultural productivity advancement behind population growth has caused intense land use conflicts, particularly between the agricultural and the forestry sectors. To compensate for the low agricultural productivity, deforestation for arable land expansion has been the principal land use conversion employed in Uganda and in particular in Nakasongola for centuries. There are several repercussions of such land use conversion, the most important in Uganda’s and in particular in Nakasongola context being accelerated soil erosion and deterioration of soil nutrient status (FAO, 1986). However, Nakasongola is known not only for the severity of land degradation, but also, since the last decades, for the concentrated efforts taking place to redress these problems including construction of stone terraces and soil bunds, protected areas and afforestation (Osiru and Hahn, 1994). The protected areas, which are a type of land management implemented on degraded, generally open access land, are a mechanism for environmental rehabilitation with a clear biophysical impact on large parts of the formerly degraded commons. In places where protected areas are established, particularly in the western part of the country, they