EFFECTS OFPOND FERTILIZATION ON THE PHYSICO-CHEMICALWATER
QUALITYOFSELECTED EARTHEN FISHPONDS IN IFE NORTH LOCAL
GOVERNMENTAREA, OSUN STATE, NIGERIA
ADEDEJI, A.A.* andADENIYI, I.F.
Department of Zoology,
Obafemi Awolowo University, Ile-Ife, Nigeria
*Corresponding author: bbkadedeji@yahoo.com; bbkadedeji@oauife.edu.ng
Abstract
The effect of fertilization on the physico-chemical water quality of six selected earthen fishponds in Ife North Local
Government Area of Osun State was investigated for a period of two years sampling the ponds every other month. The
fishponds were grouped with regard to fertilization practice and water flowage regime into three sets comprising two non-
flow-through ponds that received organic and inorganic fertilizers (FNF); two flow-through ponds that received the same
organic and inorganic fertilizers (FF) and two unfertilized flow-through ponds. The investigated water quality parameters
include water temperature, pH, transparency, dissolved oxygen, major ions, some plant nutrients and heavy metals using
standard titrimetric and instrumental methods of analysis.The mean values of these parameters were not statistically
different (p> 0.05) for the three sets of fishponds with the exception of sodium, Alkalinity, HCO3-, Conductivity and TDS
which were each characterized with significant mean differences (p= 0.05). In general, the fertilized ponds were characterized
by higher mean values in 24 of the 29 investigated water quality parameters than the non-fertilized ponds. Also the mean
values of 22 out of the 29 investigated parameters were generally higher in the flow-through ponds than in the non-flow-
through ponds. Increase in the parameters due to water flowage was statistically significant (p> 0.05) for sodium, alkalinity,
bicarbonate, conductivity and TDS while the effect of fertilization was higher for the dissolved oxygen parameters, nutrients
(NO3, PO4,), major ions and apparent colour. Thus, the fertilized ponds were more saline (based on conductivity and TDS),
better buffered and richer in nutrient than the unfertilized ponds. These effects were enhanced by flowage hence the
fertilized flow-through ponds were characterised by the most suitable water quality for fish culture in the study-area while
the fertilized non flow-through ponds was least suitable. The study revealed that to achieve the desired effect, pond
fertilization must be accompanied by adequate water flowage especially in shallow fishponds.
Keywords:water quality, fertilization, flow regime, fishpond, Nigeria.
Accepted: April 9, 2013.
Introduction
Pond fertilization provides essential nutrient components
such as nitrogen, phosphorus, and potassium compounds
required for rapid phytoplankton development and hence
increased primary and post-primary production in
fishponds without the risk of dietary diseases to fish
(Ita, 1980). The main purpose of pond fertilization is to
increase the available natural food (phytoplankton and
© The Zoologist, 11:13-20 (2013), ISSN 1596 972X.
Zoological Society of Nigeria.
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zooplankton) for fry or larval fish, or for fish species
that are efficient filter feeders (Brunson et al 1999).
However, pond fertilization may play a major role in
determining water quality and could be detrimental to
fish survival. For instance excessive fertilization rates
result in deterioration of water quality manifested as
low dissolved oxygen content, high un-ionized ammonia,
high pH levels, and high biological oxygen demand, all
14 The Zoologist
which reduce fish survival and yield (Ngbede, 1996
and Ludwig, 2002).
To prevent the deterioration of the pond environment
by the accumulation of large amounts of metabolites
being continuously excreted into the pond, and
unconsumed feeds which often add to the bottom load,
pond water should ideally be continuously freshened
by a flow-through system (Baluyut, 1989). In view of
this, a flow-through system of water management that
allows the simultaneous entry and exit of water into
and out of the pond is essential in any high-density
culture system.
The proper management of fertilizer application and
water flowage is a sustainable way of minimizing the
detrimental effect of pond fertilization and ensuring good
water quality for increased fish production (Ajao, 1999;
Ludwig, 2002). This was the motivation for this study,
which aimed at determining the effect of pond
fertilization and water flowage on the physico-chemical
water quality of selected fishponds (of a commercial
farm) in a sub-urban community in Osun State, Nigeria.
The study also assessed whether the water quality
parameters involved were within desirable limits for
fish culture or not.
Area of study
The fish ponds investigated belong to a commercial
fishing company, Niger Feeds and Agricultural
Operations Limited (NIFAGOL), located in Yakoyo-
Origbo, in Ife North Local Government Area (LGA)
of Osun State. The LGA comprise mainly rural and
semi-urban communities which lies roughly between
Latitudes 07o 25’-07o 40’N and Longitudes 004o 25’-
004o 30’E, on a general elevation range of 250-265 m
above mean sea level. River Shasha (one of the major
waterbodies in the south-west) drains the LGA nd other
waterbodies including swamps, springs, streams and
minor rivers.
The fish farm studied (NIFAGOL) comprised 18
ponds of varying sizes (ranging from 432m2to 6,383m2),
each rectangular in outline and are generally shallow.
Water supply into the ponds is from a reservoir (surface
area of 2 hectares) located within the farm. The
aquaculture practice in the farm was semi-intensive
with some of the ponds receiving organic fertilizers in
the form of chicken droppings and cow dung while
others had inorganic fertilizers (NPK) application as
deemed fit by the pond management. The stocked fish
in all the ponds were fed twice daily at the rate of 3%
of the fish body weight using the supplemental feed
(pelleted feed). The locally pelleted feed made from
mixture of maize, soybeans, fishmeal, millet, palm
kernel cake, groundnut cake and palm kernel oil, and
brewer’s waste. The water retention period for the
fertilized ponds was six months while the unfertilized
ponds were flowing-through and left undrained. In all
the culture ponds, fish stock density was 3 fish/m2. In
the majority of the ponds, Clarias gariepinus are being
in monoculture and in combination with Oreochromis
niloticus in polyculture in the flow-through ponds.
Materials and method
Of the eighteen ponds in NIFAGOL fish farm, only ten
ponds were operational during the present study. Water
samples for water quality determinations were collected
from six of these ten ponds every other month over a
period of two years from February 2006 to February
2008. For the purpose of this study, the ponds were
grouped into three sets with regard to fertilization
(fertilizer treatment) and water flowage based on the
existing culture practices. The first sets of two ponds,
fertilized non-flow-through ponds (FNF) received
organic and inorganic fertilizers and were non-flow-
through ponds. The second sets of two ponds, fertilized
flow-through ponds (FF) received organic and inorganic
fertilizers as FNF but were flow-through ponds. The
third sets of two ponds, not fertilized flow-through (NFF)
received no fertilizer but were flow-through ponds.
Water temperature measured in situ with a
mercury-in-glass bulb thermometer while pH was
determined colorimetrically on the field using a Lovibond
pH comparator. Water transparency was also
measured in situ using a graduated secchi disc. The
samples for the determination of dissolved oxygen
(DO) collected in a 250/125 ml capacity glass reagent
bottles, fixed in the field using Winkler’s reagents and
brought to the laboratory for further processing.Water
samples (61 samples) for the determination of other
chemical parameters collected in 2Litre polyethylene
jerry cans. The samples were analysed for apparent
colour and turbidity by colorimetric method (Mackereth
et al 1978). The analysis of the water samples were in
accordance with standard methods of Golterman et
al. (1978), Mackereth et al (1978) and APHA et al
(1992) as applicable. The chemical parameters analysed
include major ions (Ca2+, Mg2+, Na+, K+, Cl–, SO4
2–,
HCO3
–), salinity parameters (Conductivity, Total
Dissolved Solid), plant nutrient and oxygen parameters
(Organic matter, nitrate, PO4
3–), and heavy metals (Cu,
Pb, Mn, Ni). Data obtained subjected to analysis of
variance (ANOVA) using SPSS software (SPSS,
2008).
Adedeji and Adeniyi: Effect of pond fertilization on water quality of earthen fishponds 15
Results
Most of the investigated water quality parameters
occurred within wide range of values. However their
mean and median values were very close with the
former slightly higher than the latter suggesting slight
positive skewness of the data set (Table 1). Based on
their mean values, the investigated water quality
parameters of the fishponds occurred over the following
range of mass concentrations:
i. < 0.1mgL-1= Mn > Pb > Cu > Ni (heavy
metals).
ii. 0.1-1.0 mgL-1 = PO4> NO3(nutrients).
iii. 1.1-10.0 mgL-1 = Mg > K > Organic Matter>
Organic Carbon>DO.
iv. 10.1-100.0 mgL-1 = Alkalinity> Turbidity
(NTU)> Cl > Ca >Na >SO4> Acidity.
v. > 100mgL–1= Apparent color (Pt.Co), HCO3
–,
Conductivity (‚Scm-1), Total dissolved solids,
DO saturation (%).
The annual mean values for most of the parameters
were not statistically different (p> 0.05) among the
three sets of fishponds (Table 2) except Na+, Alkalinity,
HCO3
–, Conductivity and TDS which were each
characterized with significant mean differences
(p <0.05) among the three pond types. These five
parameters and most of the other parameters all
occurred in the mass ranking order of FF > NFF >
FNF for the three pond types. In general the fertilized
ponds (FF and FNF) were characterized by higher mean
values in 24 of the 29 investigated water quality
parameters than the non-fertilized ponds (NFF). For
these 24 parameters, the fertilized ponds (FF and FNF)
were on the average about 1.17 times or 17% (range =
1.01-1.44 times) higher than the unfertilized ponds
(NFF). On the other hand, only four parameters
(transparency, pH, manganese and lead) were higher
in the non-fertilized ponds than in the fertilized ponds,
on the average about 1.25 times (range = 1.004-1.754)
higher.
The effect of water flowage on the ponds was also
observed in 22 out of the 29 investigated parameters.
These parameters were generally higher in the fertilized
flow-through ponds (FF) than in the fertilized non-flow-
through ponds (FNF), (Table 2). They include oxygen
parameters (DO, BOD5, DO % sat), all major ions,
two of the heavy metals (Pb and Cu) and transparency.
On the average, the major ions (Ca2+, Mg2+, Na+,
K+, Cl–, SO4
2–, HCO3
–) were about 1.32 times or 32%
(range = 1.010-1.497 times) higher in the flow-through
ponds (FF) than in the non-flow-through ponds (FNF).
While the mean values of apparent colour, turbidity,
Organic matter, organic carbon, phosphate, manganese
and nickel were slightly higher (p> 0.05) in the non-
flow- through ponds (FNF) than in the flow-through
ponds (FF), (Table 2). On the average, these parameters
were 1.20 times higher in the non-flow- through ponds
(FNF) than in the flow-through ponds (FF).
The seasonal pattern of variations in the three pond
types were similar for water temperature, sodium,
chloride, pH, conductivity, total dissolved solids,
manganese and lead which were all higher during the
dry season than in the rainy season (Table 3). On the
contrary, depth, calcium, alkalinity, bicarbonate, acidity,
BOD5and copper were higher in the rainy season than
in the dry season. Significant seasonal differences
(p<0.05) occurred among the three pond types for
water temperature, sodium and manganese during the
dry season and for alkalinity, bicarbonate, acidity, BOD5,
depth and copper during the rainy season. The other
parameters (apparent colour, turbidity, magnesium,
nitrate, dissolved oxygen, organic matter, organic carbon,
nickel) were not governed by any definite seasonal
pattern (Table 3), as they varied differently among the
different pond types over the two seasons involved.
The Jaccard index of association (based on seasonal
mean value of the parameters) between the two
fertilized ponds (FF and FNF) showed perfect
association (JI = 1.000) while the relationship between
the two flow-through ponds (FF and NFF) which
although very high was less than 1.000 (JI = 0.966).
Similarly, the correlation coefficient value of 0.991
between the two fertilized-ponds (FNF and FF) was
slightly higher than the value of 0.983 between the two
flow-through ponds (FF and NFF). The effect of
fertilization was also reflected on the seasonal mean
values of turbidity, phosphate, organic matter and
manganese which were significantly different (p<0.05)
between the fertilized-ponds and non-fertilized ponds.
The effect of water flowage was also reflected in the
seasonal mean values some of the parameters (apparent
colour, transparency, magnesium, sulphate, nitrate and
copper), but the differences between the flow-through
ponds and non- flow-through ponds were not statistically
significant (p> 0.05).
Discussion
Most of the investigated water quality parameters
remained within the desirable range for optimal
aquacultural productivity except turbidity (1.5-174.2
NTU) and phosphate (0.07-1.82 mg/l) in all the ponds
throughout the period of study (Table 4; Boyd, 1998).
The result has revealed that fertilization could cause
slight increase in all the essential nutrients (nitrate,
16 The Zoologist
Table 1: Descriptive statistics of the water quality parameters of earthen fish ponds in NIFAGOL Farm, Osun State,
Nigeria, 2006-2008.
Descriptive Statistics
Parameter Mean Standard
Deviation Standard
Error of
Mean
Median Minimum Maximum Range Skewness Kurtosis
Air Temperature
(ºC) 31.20 3.0 0.399 31.00 27.00 37.00 10.00 0.235 -1.348
Water
Temperature(ºC) 31.00 1.4 0.188 31.00 28.00 33.00 5.00 -0.413 -0.864
Apparent Colour
(Pt.Co) 598.20
423.4 55.600 470.40 66.50 1739.80 1673.30 1.104 0.608
Turbidity (NTU) 58.00 43.6 5.727 44.00 1.50 174.20 172.70 1.150 0.543
Transparency (m) 0.26 0.1 0.018 0.27 0.02 0.61 0.59 0.248 -0.554
Depth (m) 0.54 0.2 0.024 0.53 0.20 1.05 0.85 0.342 -0.155
Calcium (mg/L) 16.90 4.7 0.620 16.40 8.30 29.00 20.70 0.171 -0.378
Magnesium mg/L) 2.00 1.9 0.252 1.80 0.10 7.70 7.60 1.217 0.990
Sodium (mg/L) 13.20 3.8 0.500 12.70 7.00 24.90 17.90 0.713 0.652
Potassium (mg/L) 8.94 2.4 0.310 8.80 4.80 15.20 10.40 0.576 0.211
Chloride (mg/L) 29.90 20.6 2.711 25.50 6.80 118.10 111.30 1.903 5.401
Sulphate (mg/L) 14.98 6.6 0.873 13.20 8.40 49.80 41.40 3.021 12.923
Phosphate (mg/L) 0.88 0.5 0.0590.90 0.07 1.82 1.75 -0.174 -0.903
Nitrate (mg/L) 0.83 0.1 0.017 0.82 0.68 1.49 0.81 2.467 9.859
Alkalinity (mg/L
CaCO3)108.40 36.3 4.773 102.00 42.00 214.00 172.00 1.419 2.307
HCO-3 (mg/L) 132.10 44.4 5.825 124.00 51.00 261.00 210.00 1.419 2.304
Acidity (mg/L
CaCO3)12.80 12.4 1.626 10.00 0.00 70.00 70.00 2.533 7.806
pH 7.55 0.5 0.067 7.39 6.07 8.41 2.34 -0.013 -0.195
Conductivity
(µscm-1 )226.10 51.7 6.789 227.50 120.00 338.00 218.00 0.070 -0.803
TDS (mg/L) 120.10 17.42.290 121.50 84.00 157.00 73.00 0.006 -0.859
Dissolved Oxygen
(mg/L) 6.23 2.4 0.312 6.40 2.00 15.20 13.20 1.079 2.935
DO Saturation (%) 83.80 32.2 4.229 83.20 26.20 204.90 178.70 1.054 2.841
BOD5(mg/L) 4.44 2.6 0.347 4.00 0.40 11.50 11.10 0.655 0.041
Organic Matter
(mg/L) 8.58 4.9 0.645 8.30 1.70 25.20 23.50 1.495 2.919
Organic Carbon
(mg/L) 5.05 2.8 0.372 4.90 1.00 14.60 13.60 1.450 2.844
Nickel (µg/L) 0.28 1.00 0.000 0.00 0.00 3.00 3.00 2.852 7.165
Manganese (µg/L) 37.00 36.00 0.005 22.00 8.00 134.00 134.00 1.850 2.032
Lead (µg/L) 32.00 47.00 0.006 0.00 0.00 170.00 170.00 1.469 1.257
Copper (µg/L) 4.00 4.00 0.001 3.00 0.00 15.00 15.00 1.171 0.445
Adedeji and Adeniyi: Effect of pond fertilization on water quality of earthen fishponds 17
Table 2: Mean values of physico-chemical parameters of the investigated fish ponds in NIFAGOL Farm, Osun State,
Nigeria, 2006-2008.
Pond ANOVA
FNF FF NFF
Parameter
Range Mean ƒ S.D. Range Mean ƒ S.D. Range Mean ƒ S.D.
F value P
Air Temperature (ºC) 27.0-35.5 30.4 ƒ 3.1a 27.0-37.0 31.5 ƒ 3.1a 27.0-36.0 31.4 ƒ 2.9a 0.848 0.434
Water Temperature(ºC) 29.0-33.0 30.9 ƒ 1.4a 28.0 -33.031.1 ƒ 1.6a 28.0-33.0 31.1 ƒ 1.4a 0.461 0.634
Apparent Color (Pt.Co) 66.5-1595.6 664.5 ƒ 541.3a 181.9-1710.9 645.7 ƒ 372.6a 153.0-1739.8 528.1 ƒ 424.1a 0.080 0.923
Turbidity (NTU) 1.50-165.2 61.0 ƒ 52.1a 13.7-159.1 58.4 ƒ 35.7a 16.68-174.2 57.6 ƒ 49.2a 0.078 0.925
Transparency (m) 0.05-0.36 0.21 ƒ 0.12a 0.02-0.51 0.25 ƒ 0.13a 0.08-0.61 0.29 ƒ 0.14a 0.025 0.976
Depth (m) 0.21-0.59 0.50 ƒ 0.14a 0.20-0.85 0.65 ƒ 0.19b 0.23-1.05 0.39 ƒ 0.11c 0.825 0.444
Calcium (mg/L) 8.3-22.9 14.2 ƒ 4.8a 9.0-24.7 17.4 ƒ 4.5a 9.8-29.0 17.2 ƒ 4.5a 0.753 0.476
Magnesium (mg/L) 0.10-7.10 1.43 ƒ 2.07a 0.10-5.60 2.14 ƒ 1.62a 0.10-7.70 1.91 ƒ 1.98a 0.451 0.640
Sodium (mg/L) 7.0-15.2 9.8 ƒ 2.8a 8.6-24.9 14.4 ƒ 4.2b 8.5-20.7 13.5 ƒ 2.9b 4.173* 0.021
Potassium (mg/L) 6.10-12.908.93 ƒ 2.16a 4.80-14.8 9.02 ƒ 2.28a 4.80-15.20 8.82 ƒ 2.68a 0.380 0.686
Chloride (mg/L) 6.8-44.2 24.7 ƒ 12.2a 6.8-118.1 35.0 ƒ 26.6a 6.8-73.1 27.7 ƒ 15.8a 1.266 0.291
Sulphate (mg/L) 11.90-17.70 14.16 ƒ 1.86a 9.10-49.80 16.72 ƒ 8.68a 8.40-31.70 13.34 ƒ5.34a 1.540 0.224
Phosphate (mg/L) 0.16-1.45 0.93 ƒ 0.42 a0.11-1.42 0.92 ƒ 0.37a 0.07-1.82 0.77 ƒ 0.53a 0.388 0.680
Nitrate (mg/L) 0.75-0.89 0.82 ƒ 0.05a 0.68-1.49 0.87 ƒ 0.17a 0.68-1.15 0.80 ƒ 0.11a 1.562 0.220
Alkalinity
(mg/L CaCO3)42.0-142.0 87.8 ƒ 30.7a 82.0-214.0 120.5 ƒ 40.7b 68.0-190.0 105.9 ƒ 30.4ab 3.455* 0.039
HCO-3 (mg/L) 51 .0-173.0 103.8 ƒ 41.8a 100.0-261.0 146.9 ƒ 49.6b 83.0-232.0 129.1 ƒ 37.1ab 3.760* 0.030
Acidity (mg/L CaCO3)6.0-70.0 18.9 ƒ 19.7a 2.0-40.0 12.2 ƒ 10.1b 0.0-32.0 9.1 ƒ 6.6ab 0.348 0.708
pH 6.07-8.10 7.14 ƒ0.53a 6.90-8.41 7.61 ƒ 0.47b 7.10-8.39 7.64 ƒ 0.43b 1.396 0.257
Conductivity (µscm-1 )120.0-310.0 195.0 ƒ 55.2a 159.0-338.0 246.2 ƒ 51.8b 134.0-292.2 222.4 ƒ 41.2ab 3.783* 0.030
TDS (mg/L) 84.0-148.0 109.4 ƒ 18.6a 97.0-157.0 126.8 ƒ 17.4b 89.0-142.0 119.1 ƒ 14.0ab 3.793* 0.029
Dissolved Oxygen (mg/L) 2.00-15.20 6.24 ƒ 3.96a 2.80-11.20 6.80 ƒ 1.62a 2.40-10.40 5.65 ƒ 2.06a 1.163 0.321
DO Saturation (%) 26.2-204.9 84.1 ƒ 53.6a 36.10-148.70 91.3 ƒ 22.3a 32.1-139.2 76.3 ƒ 27.7a 1.200 0.310
BOD5(mg/L) 1.90-11.50 4.59 ƒ 3.43a 0.40-9.60 5.15 ƒ 2.26a 0.40-10.20 3.57 ƒ 2.53a 1.421 0.251
Organic Matter (mg/L) 3.30-25.20 8.94 ƒ 6.41a 1.70-22.50 8.63 ƒ 4.35a 2.40-23.60 8.54 ƒ 4.91a 0.091 0.981
Organic Carbon (mg/L) 1.90-14.60 5.18 ƒ 3.71a 1.00-13.00 5.19 ƒ 2.47a 1.40-13.70 4.96 ƒ 2.86a 0.082 0.921
Nickel (µg/L) 0.00-3.00 0.60 ƒ 1.00a 0.00-3.00 0.30 ƒ 0.70a 0.00-3.00 0.20 ƒ 0.70a 1.239 0.298
Manganese (µg/L) 13.4-16.0 53.0 ƒ 47.0a 12.0-119.0 32.0 ƒ 29.0a 8.0-122.0 34.0 ƒ 35.0a 0.856 0.431
Lead (µg/L) 0.0-60.0 10.0 ƒ 20.0a 0.0-140.0 34.0 ƒ 46.0a 0.0-170.0 42.0 ƒ 55.0a 0.535 0.589
Copper (µg/L) 0.0-12.0 4.0 ƒ 4.0a 0.0-14.0 5.0 ƒ 4.0a 0.0-15.0 4.0 ƒ 4.0a 0.419 0.660
NB:Values in a row followed by different letters are significantly different (p= 0.05).
* = Significant. FNF – Fertilized non-flow-through pond. FF – Fertilized flow-through pond.
NFF – Not fertilized flow-through pond.
