Soil carbon and agricultural productivity: perspectives from sub-Saharan Africa.

Soil carbon plays a key role in maintaining crop productivity in the soils in sub-Saharan Africa (SSA). This is more so considering that most smallholder farmers cannot afford the use of adequate amounts of inorganic fertilizers to restore the proportion of nutrients lost through crop harvests, soil erosion and leaching. Complicating the situation is the huge proportion of land under threat of degradation in the form of soil erosion and nutrient decline. There are numerous opportunities for improving soil carbon as a basis of ensuing sustainable agriculture. This paper discusses the role of soil carbon in agricultural production, with special focus on sub-Saharan Africa. First, the paper presents a discussion on the functions of soil carbon (biological, chemical and physical). This is followed by a look at the causes of carbon variation across agroecosystems. Management of soil carbon and productivity is evaluated in the context of resource availability, quality and soil organic matter pools. Drawing from the integrated soil fertility management practices in Africa, the paper discusses various strategies for organic carbon management and the implication of the same on crop productivity and soil properties. A special focus is given to the lessons learned from long-term experiments across Africa.