Carbon storage in agroforestry systems in the semi-arid zone of Niayes, Senegal

Agroforestry is an ancient practice widespread throughout Africa. However, the influence of Sahelian agroforestry systems on carbon storage in soil and biomass remains poorly understood. We evaluated the carbon storage potential of three agroforestry systems (fallow, parkland and rangeland) and five tree species (Faidherbia albida, Acacia raddiana, Neocarya macrophylla, Balanites aegyptiaca and Euphorbia balsamifera) growing on three different soils (clay, sandy loam and sandy) in the Niayes zone, Senegal. We calculated tree biomass carbon stocks using allometric equations and measured soil organic carbon (SOC) stocks at four depths (0–20, 20–50, 50–80 and 80–100 cm). F. albida and A. raddiana stored the highest amount of carbon in their biomass. Total biomass carbon stocks were greater in the fallow (40 Mg C ha−1) than in parkland (36 Mg C ha−1) and rangeland (29 Mg C ha−1). More SOC was stored in the clay soil than in the sandy loam and sandy soils. On average across soil texture, SOC stocks were greater in fallow (59 Mg C ha−1) than in rangeland (30 Mg C ha−1) and parkland (15 Mg C ha−1). Overall, the total amount of carbon stored in the soil + plant compartments was the highest in fallow (103 Mg C ha−1) followed by rangeland (68 Mg C ha−1) and parkland (52 Mg C ha−1). We conclude that in the Niayes zones of Senegal, fallow establishment should be encouraged and implemented on degraded lands to increase carbon storage and restore soil fertility.