VARIABILITY OF INFILTRATION IN THE NORTHERN GUINEA SAVANNA ALFTSOL OF NIGERIA
VARIABILITY OF INFILTRATION IN THE NORTHERN GUINEA SAVANNA ALFTSOL OF NIGERIA
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Date
1998-11
Authors
WUDDIVIRA, HASSAN NAKKA
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Abstract
The ring infiltrometer method was used to measure infiltration
rate of a savanna soil on a 60m transect, at 2m intervals. This was
done with the aim of evaluating the magnitude of spatial variation
of infiltration over a field considered uniform interms of soil
type. Philip and Kostiakov's equations were employed for
predicting infiltration rate of the soils in the field. Curve
fitting by regression techniques showed that infiltration of the
soils are adequately described by both equations (R2 > 0.98). There
was relatively high variation in infiltration rate with a mean of
27.4mm/hr and a standard deviation of 15.25mm/hr. These values
were also log-normally distributed.
Infiltration rate was poorly correlated with bulk density (r =
0.32) and porosity (r = 0.32) but it was significantly correlated
with macroporosity (r = 0.38*) at 5% level of significance.
Further analysis using autocorrelograms, showed that the steadystate
infiltration rates for the 30 points/locations were spatially
independent at the sampling intervals of 2m.
The mean and standard deviation values of saturated hydraulic
conductivity were 44.78mm/hr and 3 7.27mm/hr respectively. These
values gave rise to wide variation in conductivity measured between
points. The variation was spatially independent with a log-normal
frequency distribution. Thus, it can be unreliable to use single
determined infiltration or hydraulic conductivity value as
representative of the field.
Due to the spatial independence of the data for these
parameters, 10 and 58 samples are required to estimate the mean
steady-state infiltration rate and hydraulic conductivity for the
study area, respectively. These sample numbers are obtained within
± 10% of the population mean at the 95% confidence level assuming
normal distribution.
Description
A thesis submitted to the Postgraduate School,
Ahmadu Bello University in partial fulfillment
of the Requirements for the Degree of master of
Science (Soil Science)
Department of Soil Science
Faculty of Agriculture
Ahmadu Bello University
Zaria, Nigeria
Keywords
VARIABILITY,, INFILTRATION,, NORTHERN GUINEA SAVANNA,, ALFTSOL,, NIGERIA