THE FERTILITY STATUS OF SOILS ALONG THE MICROTOPOGRAPHY OF THE RIVER GALMA FADAMA AT ZARIA
THE FERTILITY STATUS OF SOILS ALONG THE MICROTOPOGRAPHY OF THE RIVER GALMA FADAMA AT ZARIA
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Date
1997-09
Authors
ABUBAKAR, ABDULLAHI SHEDI
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Abstract
The fertility status of soils of the River Galma Fadama at the
Kaduna State Irrigation Scheme site at Zaria was determined along
its microtopographical features (MTFs). Moving at right angle away
from the bank of the river, the MTFs consist, successively, of the
levee, levee-backslope or backslope (BSL), coverplain {CP), and
backswamp (BSW). Soil samples were taken from three replicate
sites, spaced at 100 m apart in each MTF, at three depths, 0-25,
25-50 and 50-75cm.
Silt was the highest particle-size fraction in all the MTFs,
except the levee where sand was the highest. The silt ranged from
12-54% with mean valves of 40, 40 43 and 45% in the levee, BSL, CP
and BSW, respectively. The sand fraction followed with a range of
6-58%, and mean values of 43, 28, 37 and 19% for the successive
MTFs, while clay was the lowest fraction and ranged from 12-68% and
the means for the successive MTFs were 17, 32, 20 and 34%.
Soil reaction varied from extremely acid to slightly acid (pH
3.6-6.0) with mean values of 4.8, 4.1, 4.8 and 4.3 for the levee,
BSL, CP and BSW, respectively. The exchangeable bases (Ca, Mg, K
and Na) had values whose ranges could be rated as low to high, but
the mean values for the individual MTFs could be rated as medium,
except K which was high in the levee and Na which was high in all
MTFs, except the CP. Exchangeable acidity was relatively high
ranging from 0.8-8.6 cmol(+) kg"1 soil, with mean values of 3.5,
4.6, 3.6 and 3.1 cmol( + ) kg"1 in the levee, BSL, CP and BSW
respectively.
The effective CEC (ECEC) ranged from 3.1-13.0 cmol(+) kg _1
with respective mean values of 7.4, 7.8, 7.6 and 7.0 cmol(+) kg"1
on the levee, BSL, CP and BSW. The CEC (NH4OAc) varied from 10.0-
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34.0 cmol(+) kg-1 and, in the same order as ECEC, the means values
were 20.4, 19.5, 16.9 and 15.1 cmol(+) kg-1 while base saturation
ranged from 22-94% and the mean values for the successive MTFs were
41, 35, 41 and 42%.
Organic C and total N values were generally low ( < 1.0% and
< 0.2%, respectively) with low mean values in nearly all MTFs,
while available P, even though generally low (< 10 mg kg-1) had some
exceptionally high values (> 20 mg kg-1) in the Ap horizons of at
least one site in each MTF.
Among the MTFs, correlation among soil properties was greatest
in the BSL, followed by the levee and CP and was least in the BSW.
In decreasing order, ECEC, clay and exchangeable acidity had the
highest numbers of correlations, while organic C and pH (water) had
fewer numbers of correlation with other soil properties.
From the selected fertility parameters, pH (both water and
CaC12), organic C, total N, CEC, ECEC, clay and exchangeable
acidity, the fertility status of the individual MTFs could be
placed in the order BSW > CP > BSL > levee. However, due to
drainage impairment, which decreased in this order of fertility
ranking of the MTFs, and also due to textural variation which
affect chemical properties, the intensity of cropping on the fadama
was in the order BSL > levee > CP > BSW.
The arithmetic modelling method of land suitability evaluation
on the other hand showed that the levee, BSL, and CP were all
moderatetly suitable (S2) for arable cropping, while the BSW was
curently not suitable (Nl). Liming, organic matter addition and
subsequent maintenance and appropriate fertilization were
recommended for optimum crop production on the fadama.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF A MASTER DEGREE IN SOIL SCIENCE
DEPARTMENT OF SOIL SCIENCE
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY, ZARIA
Keywords
FERTILITY,, STATUS,, SOILS,, MICROTOPOGRAPHY,, RIVER GALMA,, FADAMA,, ZARIA