Biomass carbon: litter quality and implications for carbon sequestration by agroforestry in coastal Kenya

Abstract

The potential impact of agroforestry systems on C sequestration is widely recognized. However limited data is available on its impact on C dynamics, as much of the previous research has been focused on agricultural productivity. This research was therefore conducted to determine biomass carbon and litter quality of commonly recommended improved fallow species, at the coastal region in Kenya. An on-farm experiment was established in 2006 at a coastal Kenya site, using a Randomized Complete Block Design with five agroforestry species replicated thrice. Biomass carbon and litter quality was assessed at 6 and 12 months after sowing (MAS). Data was analysed using R version 2.9.0. The effects of species, measurement time and their interaction on total carbon were highly significant (P < 0.001). Total carbon stocks at 6 MAS ranged from 0.04 ('S.sesban') to 1.4 Mg C /ha ('M.pruriens') compared to 1.7 ('S.sesban') to 20.3 Mg C /ha ('T.candida') at 12 MAS. Results indicate that substantial amounts of C were sequestered in the biomass. However, duration of the fallow is a key factor to be considered. Litter quality was high with average polyphenol contents of 2.6 % while lignin contents were highest in 'T.candida' (16.3 %).