Abstract:
Landlocked States in Nigeria are daily faced with the reality of the need for rapid
agricultural development for socio-economic transformation. The magnitude of the
need for most of the States requires massive mechanisation of the agricultural
production process and this comes with its attendant environmental problem. Thus it
is desirable that a pre-investment investigation be carried out on soils for sustainable
development. In this study, the mineralogy of agricultural soils in selected parts of
Ekiti State, Southwest Nigeria were investigated from washed salt-free, freeze-dried,
fine clay fraction of samples from the sites using x-ray diffractogram. The selected
parts included: Oye-Ekiti, Ire-Ekiti and Ikere-Ekiti. The chemical compositions were
determined using standard procedures. The load bearing (support) capacity at
different moisture content were established from the plot of pre-compression (preconsolidation) pressure at varying moisture regimes. The relationship between load
support capacity and soil mineralogy for soil was thereafter examined. The result
showed that the mineralogy of the studied sites were Ikere - Oxisols, Ire - Inceptisols,
and Oye - Ultisols. Moisture retention capacity ranges in the studied sites were
generally low viz Ikere; 0.05 - 0.20 kg/kg, Ire A horizon; 0.05 - 0.23 kg/kg; Ire B
horizon; 0.03 - 0.35 kg/kg, Oye A horizon; 0.05 - 0.20 kg/kg, and Oye B horizon;
0.10 - 0.25 kg/kg. Load Support capacity (500kPa) were highest in Ultisols samples
from Oye B-Horizon and the Oxisols from Ikere. It can be concluded that most
samples from agricultural sites in Ekiti State would support mechanisation of the
farming process. However, due to the low moisture retention ranges, shallow depth
and the thinness of the A- Horizon, mechanisation process should be carefully
handled in order not to destroy the soil structurally. Experience from literature suggest
that such soil need more preparatory steps, with medium size implement to avoid
losing soil layer above the preconsolidation pressure, when natural recovery will be
impossible and degradation will be rapid. This study has laid a good foundation for
large-scale estimation of soil workability data for similar soil types in Southwest
Nigeria. It appears that soil trafficability in cultivation could be inferred from the
compression and mineralogy characteristics.
