Soil Organic Carbon Storage in Cof fee Agroforestry Systems: A review

Abstract

Agroforestry systems (AFS) are sustainable production alternatives that ef ficiently store more carbon than crop monoculture. However, the simplification of AFS, in terms of canopy structure and species diversity, af fects their carbon sequestration capacity. This work aimed to assess the soil organic carbon (SOC) stocks of cof fee agroforestry systems with distinctive shade gradients at 0-30 and 30-100 cm depths in dif ferent regions of the world. A literature review on SOC storage in cof fee agroforestry systems at the global level was carried out. The cof fee production systems were classified into three groups according to the shade gradient: traditional system (TS) with dense shade, specialized system (SS) with medium shade, and full-sun system (FSS) with no shade trees. TS stored 95 Mg SOC ha-1 at 0-30 cm depth, followed by SS with 83 Mg ha-1, and FSS with 69 Mg ha-1. At 30-100 cm, TS stored 224 Mg ha-1, SS 186 Mg ha-1, and in FSS 126 Mg ha-1. The cof fee AFS in the tropical region has an average of 76 Mg SOC ha-1 at 0-30 cm depth and 170 Mg ha-1 at 30-100 cm. The AFS in the temperate region stored an average of 74 Mg ha-1 at 0-30 cm and
115 Mg ha-1 at 30-100 cm. The global median SOC stock of cof fee AFS was
253 Mg SOC ha-1 to one-meter depth. Our study highlighted that the density of shade trees in cof fee AFS significantly af fects SOC storage, especially in the subsoil. Reinforcing the importance of cof fee AFS for storing SOC and mitigating climate change, this review highlights the need to study SOC at deeper soil profiles to fully understand the variation in soil carbon sequestration capacity of the diverse cof fee agroforestry systems around the world.