Agroforestry Systems and Soil Carbon Storage: Short-Term Versus Long-Term Management Implications.

Since carbon movement through soil can be a long-term process, the effect of a specific management practice or land-use system (LUS) may not be clear in a short time-span; however, most studies on C sequestration are of a short-term nature.  Therefore, it is important to develop methods that can be useful in assessing the long-term C sequestration potential (CSP) of soils across land-use systems (LUS).  Our recent studies on C storage in different soil fraction-size classes at varying soil depths up to 1 m under different agroforestry systems (AFS) in six different ecological regions in five countries (Florida, USA; Mali, West Africa; Kerala, India; Central and Northwestern Spain; Bahia, Brazil; and Minas-Gerais, Brazil) showed that C stock measurements in different fraction sizes supplemented by information on the nature of soil aggregates can give insights into the long-term CSP of the soil. Furthermore, long-term land-use history has a bearing on the amount of C stored in soils, and relatively high soil C stocks could be present in little-exploited areas such as the Cerrado (savanna) of Brazil. Opening up these lands for commercial use could lead to release of C to atmosphere and degradation of the ecosystem. Adoption of tree-based integrated LUS such as agroforestry will help retain these C stocks in soils and minimize the CO₂ (GHG) emission.