Soil Carbon in Agroforestry Systems: An Unexplored Treasure?
- Kumar, B. Mohan
- Nair, Vimala
- Howlett, David
- Takimoto, Asako
- Gama-Rodrigues, Emanuela
- Saha, Subhrajit
- Haile, Solomon
- Nair, P. K. Ramachandran
- Tonucci, Rafael
- Garcia, Rasmo
- Mosquera-Losada, M.-Rosa
ISSN: 1756-0357
Ano de publicación: 2009
Tipo: Artigo
Outras publicacións en: Nature Precedings
Resumo
AbstractSoil organic matter (SOM), which contains more reactive organic carbon (C) than any other single terrestrial pool, plays a major role in determining C storage in ecosystems and regulating atmospheric concentrations of carbon dioxide (CO2)^1^. Agroforestry, the practice of growing trees and crops in interacting combinations on the same unit of land^2^, primarily by resource-poor smallholder farmers in developing countries, is recognized as a strategy for soil carbon sequestration (SCS) under the Clean Development Mechanism (CDM) of the Kyoto Protocol^3^. The understanding about C storage and dynamics under agroforestry systems (AFS), however, is minimal. Our studies under various AFS in diverse ecological conditions in five countries showed that tree-based agricultural systems, compared to treeless systems, stored more C in deeper soil layers up to 1 m depth under comparable conditions. More C is stored in soil near the tree than away from the tree; higher SOC content is associated with higher species richness and tree density; and C3 plants (trees) contribute to more C in the silt- + clay-sized (<53 &x00B5;m) fractions that constitute more stable C, than C4 plants, in deeper soil profiles4 - 8. These results provide clear indications of the possibilities for climate change mitigation through SCS in AFS, and opportunities for economic benefit - through carbon trading - to millions of smallholder farmers in developing countries.