Soil fertility decline caused by deforestation,
soil degradation and low input use has become a
primary factor limiting sustainable utilization of soil
resources in cocoa agroforestry systems on acid soils
in lowland humid Ghana. Changes in and responses of
soil physico-chemical properties and soil quality to
land-use change was investigated along a chronosequence
of farm fields on a Ferric Lixisol in the Ashanti
region of Ghana. Soil bulk density increased significantly
only in the top 0–10 cm soil layer. Concentrations
and stocks of soil organic carbon (SOC) and total
N decreased significantly in the top 0–10 and
10–20 cm soil depths. By 30 years after forest
conversion, cocoa system had re-accumulated up to
38.8 Mg C ha-1 or 85 % of initial forest carbon stock
values. Total porosity (%) decreased significantly in
shaded-cocoa fields in comparison with the natural
semi-deciduous forest. An assessment of soil deterioration
using degradation indices (DIs) revealed that
total soil quality (0–20 cm) deteriorated significantly
(DI = –60.6) in 3-year-old of cocoa system but
improved in 15 and 30-year-old systems. Available P
stocks declined consistently while soil exchangeable