Functional Relationships between Soil Fertility and Organic Matter Dynamics as Affected by Human Activities in Southern African Savannah

An integrated study at regional scale was undertaken on scats of semi-and savanna areas from some southern African countries for the purpose of: a)Monitoring soil status and quality, including the assessment of the role of OM on soil fertility and productivity and its potential for effective carbon sequestration; b)Identifying appropriate strategies for land use, farming systems and agronomic practices for the long-term sustainable management of soil resources. Soil types were selected on the basis of their distribution in the region (mainly Arenosols and Luvisols) or of their relevance for development of sustainable and productive farming systems (Vertisols). The inherent constraints with a probable bearing on the fertility. productivity and the carbon dynamics of selected soil types, under pressure of human activities, are examined and suitable options for soil use and management are proposed. In Arenosols and susceptible Luvisols. cultivation has often lead to a rapid decay of productivity and soil quality, mostly due to decrease of organic matter levels followed by physical degradation, and nutrients depletion. As a consequence inherently infertile Arenosols are, in general terms, unsuitable for sustainable agriculture in the absence of adequate and costly inputs. Susceptible Luvisols can be protected from physical degradation by maintaining an adequate level of organic matter and by protecting the topsoil from kinetic rain energy by mulching with straw or similar materials. Vertisols, showing a moderate resilience to the impact of human activities