Contribution of trees to soil carbon sequestration under agroforestry systems in the West African Sahel |
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| Authors: | Asako Takimoto Vimala D Nair P K Ramachandran Nair |
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| Institution: | (1) University of Florida, Gainesville, FL 32611, USA |
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| Abstract: | Consequent to recent recognition of agricultural soils as carbon (C) sinks, agroforestry practices in the West African Sahel
(WAS) region have received attention for their C sequestration potential. This study was undertaken in the Ségou region of
Mali that represents the WAS, to examine the extent of C sequestration, especially in soils, in agroforestry systems. Five
land-use systems were selected in farmers’ fields two traditional parkland systems, two improved agroforestry systems (live
fence and fodder bank), and a so-called abandoned land]. Soil samples taken from three depths (0–10 cm, 10–40 cm, and 40–100 cm)
were fractionated into three size classes (2,000–250 μm, 250–53 μm, and <53 μm) and their C contents determined. Whole-soil
C contents, g kg−1 soil, across three depths ranged from 1.33–4.69 in the parklands, 1.11–4.42 in live fence, 1.87–2.30 in fodder bank, and
3.69–5.30 in abandoned land; and they correlated positively with silt + clay content. Using the 13C isotopic ratio as an indicator of relative contribution of trees (C3 plants) and crops (C4 plants) to soil C, more tree-origin
C was found in larger particle size and surface soil and indicated that long-term tree presence promoted storage of protected
C in deeper soil. Existing long-standing agroforestry practices of the region such as the parklands seemed to have little
advantage for sequestering additional C, whereas improved agroforestry practices such as live fence and fodder bank introduced
in treeless croplands seemed to be advantageous. |
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| Keywords: | 13C/12C Fodder bank Live fence Mali Parkland systems Soil fractionation |
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