Soil organic carbon plays a key role in soil as an important regulator of environmental constraints to crop productivity. In semi-arid West Africa, soils are characterised by low carbon content (< 1 %) and nitrogen and phosphorus deficiencies. Hence these soils are unable to provide sufficient environmental services. A study to assess the impact of management practices on soil carbon build-up has been conducted in Burkina Faso from 2000 to 2001. The effects of tillage, soil fauna and nitrogen fertiliser on soil carbon build-up have been investigated under a split plot design on a Ferric Lixisol and a Eutric Cambisol. Soil carbon build-up requires judicious combination of low quality organic resources and nitrogen input in tilled systems. In no-till systems high quality organic amendments favoured soil carbon buildup but soil and water conservation measures are needed to reduced organic matter and nitrogen losses. Soil fauna play a key role in the decomposition of low quality organic materials and its incorporation into the soil. However, in nitrogen deficient soil, nitrogen input is needed to maintain soil organic cabon level. Soil carbon build-up in semi-arid West Africa is an art of balancing, taking into account nitrogen status of the soil, nitrogen inputs, the quality of organic amendments and soil tillage.