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335 Ekpe et al., Effect of Organic Waste…
Futo Journal Series (FUTOJNLS)
e-ISSN : 2476-8456 p-ISSN : 2467-8325
Volume-2, Issue-2, pp- 335 - 345
www.futojnls.org
Research Paper December 2016
Effect of Organic Wastes on Soil Heavy Metal
Concentration and Growth Characteristics of Cucumber
(Cucumis Sativus L.) in an Ultisol
Ekpe I.I1, Okere, S. E.2 , Agim L.C1, Ahukaemere,C.M, Ihemtuge, S. C.1,
Okoye, C.1, , Onuora M.D.1 and Nwaigwe M.O.3
1Department of Soil Science and Technology, School of Agriculture and Agricultural
Technology, Federal University of Technology Owerri P.M.B 1526 Imo state
2Department of Crop Production Technology, School of Agriculture and Agricultural
Technology, Federal University of Technology Owerri P.M.B 1526 Imo state
3Department of Vocational Education, Alvan Ikoku |College of Education, Owerri, Imo
State
Corresponding Authors E-Mail: ibiamik@yahoo.com
Abstract
An experiment was set up in the 2014 and 20015 cropping seasons to compare the
effect of organic wastes as humanure and rumen digesta on soil heavy metal
concentration and growth characteristics of cucumber in an Ultisol in Imo State,
southeast Nigeria. The study was conducted at the Teaching and Research Farm of
the School of Agriculture and Agricultural Technology, Federal University of
Technology, Owerri. The treatments comprised of ; T1- Control = 0 kg/ha; T2 -
Humanure = 10 t/ha; T3 - Rumen digesta = 10t/ha; T4 - Humanure + Rumen digesta
= (5 + 5 t/ha) and T5 - Humanure + Rumen digesta = (10 + 10 t/ha). The experiment
was laid out in randomized complete block design (RCBD) and data analyzed using
Analysis of Variance (ANOVA) at p = 0.05 probability level. Significant differences
were separated with F-LSD. The results obtained showed that both humanure and
rumen digesta were good sources of organic manure at the used rates because they
did not increase the soil heavy metal properties beyond the WHO permissible limits.
There were significant increases in the number of leaves, and branches, relative to
the control. The leaf area, vine length, and number of fruits were not affected
significantly by the application of the treatments.
Keywords: Cucumber, Growth, Heavy, Humanure, Metal, Rumen
336 Ekpe et al., Effect of Organic Waste…
1.0 Introduction
Heavy metals are metallic elements with specific gravity greater than 5, such as
cadmium, copper, lead and zinc (Brady and Weils,2002) that are found in the
environment and are harmful to man, plants and animals. A feature that heavy
metals have in common is that they tend to accumulate in the bodies of organism
that ingest them. Recently scientists are encouraging the use of organic wastes for
soil enrichment in farming because wastes can supply virtually all the nutrients
required by plant and improve soil physical and biological conditions for sustainable
crop production and environmental safety without paying sufficient attention to their
heavy metal contribution to the environment. These wastes also add to the pool of
heavy metals in the soil which can become a major problem militating against quality
yield of crop. These metals disturb the normal biological or biochemical processes in
living organisms (Brady and Weils 2002).
The concentration of heavy metals increases up the food chain. For instance,
some marine algae may contain heavy metals at concentrations up to one hundred
times that of the water in which they are living. Small fishes eating the algae develop
higher concentrations of heavy metals in their flesh; larger fishes that feed on the
smaller ones imbibe higher concentrations of the metals and so on, up to fish eating
birds or mammals (Jenkins,2005). The humans who produce humanure invariable
return these heavy metals to the soil and few people seem to realize that metals lost
to our environment pose human health problems(Jonsson et al.,2004). Japanese itri-
itri disease was traced to the consumption of rice grown in cadmium contaminated
irrigation water, while brain damage and incidences of lung cancer have been
attributed to lead and nickel contamination respectively. (FAO,1997 ; M.O.S.E.S,
2009;Thao,1998). The liver, the kidney, respiratory and reproductive systems are
mostly affected by heavy metals.
Micronutrient are known to function as welfare minerals to growing crops but
in excess, pose great danger to the crop, humans and the ecosystem generally
(Brady and Weils,2002). It is important, therefore, that the contributions of organic
wastes as credible substitute for inorganic fertilizer should be checked to forestall
solving one problem and creating even a bigger one in the process. It was based on
this that an experiment to evaluate the effect of humanure and rumen digesta on soil
337 Ekpe et al., Effect of Organic Waste…
heavy metal concentration and yield characteristics of cucumber in an Ultisol in Imo
South-East, Nigeria was embarked upon.
2.0 MATERIALS AND METHOD
2.1 Site Description
The study area was Ihiagwa, Imo State, southeast Nigeria. Ihiagwa is located
in the humid tropics, at Latitude 5˚24˚N and Longitude 7˚01˚E. The annual rainfall
and temperature range from 2500 – 3000 mm and 25˚C - 30˚C, respectively. Soils of
Ihiagwa are derived from alluvial and coastal plain sands.
2.2. Experimental Materials and Treatment Combinations
Seeds were bought at the Agricultural Development Programme (ADP), Owerri,
Imo State. Five (5) bags of rumen digesta were gotten from the Abattoir at Relief
Market, Imo State and 5 bags of humanure from the sewage dumping ground at
Onitsha expressway, Irete, Imo state. The treatments comprised of T1- Control at 0
kg/ha; T2 – Humanure at 10 t/ha; T3 - Rumen digesta at 10t/ha; T4 - Humanure +
Rumen digesta at (5 + 5 t/ha) and T5 - Humanure + Rumen digesta at (10 + 10 t/ha).
2.3. Field Layout and Experimental Design
There were 20 plots in the experimental field. Each of the plots measured 3 x 3 m
with 1m alley between blocks and between plots. The experiment was laid out in a
randomized complete block design with 5 treatments replicated 4 times. The
diagrammatic representation of the field layout is shown in Figure 1.
338 Ekpe et al., Effect of Organic Waste…
Fig.1. The treatment allocation in a Randomized Complete Block Design (RCBD)
with 5 treatments and 4 replications.
2.4. Soil Sampling and Laboratory Analysis
The initial and post harvest soil samples were collected at 0 – 30 cm soil depth. The
core sampler attached to a soil auger was used in the soil sampling and these
samples were used for the determination of heavy metal content of the soil. The soil
samples were air dried, crushed and sieved using 2mm size sieve in preparation for
use in analysis. Selected Heavy metals soils were determined according to the
procedure outlined by AOAC (2012) for heavy metal determination. The samples
were digested and the heavy metals were read out using Atomic Absorption
Spectrometer (AAS). The heavy metals determined were Copper (Cu), Zinc (Zn),
Cadmium (Cd), and Nickel (Ni).
2.5. Cultural Practices
The land was manually cleared using machetes; stumps were removed after which
seed beds were made using hoes and spades. The treatments were incorporated
into the soil and allowed to stand for 2 week before seed placement. Cucumber
339 Ekpe et al., Effect of Organic Waste…
variety ASHLEY was used and three seeds was planted per hole and later thinned
down to one seedling per stand, 2 weeks after planting. The planting was done at
the spacing of 50 cm x 50 cm and the arrangement gives a plant population of
40,000 plants per hectare. Weeds were controlled manually using hoe and by hand
picking to keep the plot free of weeds as regularly as the need arose.
2.6 Measurement of Growth Parameters; Three plants were tagged in each plot
and used for all the agronomic measurements:
2.6.1 Number of Fruits: This was obtained by counting the fruits harvested per plot.
2.6.2 Vine Length: The vine length was measured at flowering using meter rule
from the base of the plant to the apex leaf.
2.6.3 Number of Leaves: This was done by counting all the leaves on the three
tagged plants and the total divided by three to give average number of leaves per
plant.
2.6.4 Number of Branches: The number of branches was counted from the three
tagged plants.
2.6.5 Leaf Area: The leaf area of the three tagged plants was measured using meter
rule. The length and breadth of the leaf was measured and multiplied by a factor
0.75.
2.7 Statistical Analysis; Generated soil data were analyzed using Analysis of
Variance (ANOVA). Significant differences between means were separated using
Fishers Least Significant Difference (F-LSD) at 5% level of probability.
3.0. RESULTS AND DISSCUSION
3.1.0 Effects of Treatments on Selected Heavy Metals
The effect of humanure, rumen digesta and humanure and rumen digesta
combinations on selected heavy metals are presented in the table 1.
3.1.1 Cadmium (Cd):
The result of the treatment on soil cadmium revealed that there was
statistically significant difference when control was compared with humanure and
rumen digesta combination of 10 + 10t/ha which produced 0.025mg/kg cadmium.
Also, when the sole rumen digesta application was compared with humanure and
rumen digesta combination of 10 + 10t/ha, 0.027mg/kg cadmium was produced.
340 Ekpe et al., Effect of Organic Waste…
When humanure and rumen digesta combinations of 5 + 5t/ha and 10 + 10t/ha were
compared with each other, 0.027mg/kg cadmium was produced. There were no
significant differences when control was compared with the sole humanure; the sole
rumen digesta and the humanure and rumen digesta combination of 5 + 5t/ha
applications. Also, there were no significant differences when the sole humanure
was compared with the sole rumen digesta and humanure and rumen digesta
combinations applications. The same result was recorded when the sole rumen
digesta application was compared with humanure and rumen digesta combination of
5 + 5t/ha. The values of cadmium recorded were higher than the (0.01mg.kg-1)
permissible limits by the WHO.
Table 1: Effects of Treatments on Selected Heavy Metals
Treatment
Cadmium
(mg.Kg-1)
Zinc (mg.Kg-
1)
Nickel
(mg.Kg-1)
Copper
(mg.Kg-1)
Control
0.015ᵃ
0.240ᵃ
0.316ᵃ
14.0ᵃ
T2
0.023ᵃ
0.310ᵇ
14.480ᵇ
15.75ᵇ
T3
0.017ᵃ
0.267ᶜ
0.550ᵃ
18.25ᶜ
T4
0.017ᵃ
0.180ᵈ
0.613ᵃ
25.90ᵈ
T5
0.042ᵇ
0.145ᵉ
1.170ᵃ
25.35ᵉ
WHO Limit
0.01
15.0
6.5
1.5
F-LSD(0.05)
0.02
0.01
0.84
1.21
Keys: H= Humanure, RD= Rumen Digesta;
Note: Figures with the same super scripts are not statistically significant while
figures with different super script are significant
3.1.2. Zinc (Zn):
The result of the effect of treatment on soil Zn shows that there was significant
difference when control was compared with the treatments and when the treatments
were compared with one another. When control was compared with the sole
humanure application, the sole rumen digesta application and humanure and rumen
digesta combinations they produced 0.07, 0.027, 0.06 and 0.095mg/kg respectively.
The sole humanure when compared with the sole rumen digesta and humanure and
341 Ekpe et al., Effect of Organic Waste…
rumen digesta combinations produced 0.043, 0.13, and 0.165mg.kg-1. The
humanure and rumen digesta combinations were compared with the sole rumen
digesta application and produced 0.087 and 0.122 mg.kg-1. The humanure and
rumen digesta combinations of 5 + 5 and 10 + 10t.ha-1 when compared produced
0.035mg.kg-1. This shows that there is an increase in the zinc level of the soil with
the addition of rumen digesta and humanure. Even with this increase the zinc
concentration is far below the 15.0 mg.kg-1 permissible limits of the WHO
3.1.3. Nickel (Ni):
The result of the effect of treatment on soil Ni shows that there was significant
difference when control was compared with the sole humanure application and
produced 13.93mg/kg and when treatments were compared with one another. The
sole humanure application was compared with the sole rumen digesta application,
humanure and rumen digesta combinations, produced 14.164, 13.867, and 13.31
mg.kg-1 respectively. The sole rumen digesta application was compared with
humanure and rumen digesta combination of 5 + 5t.ha-1, produced 0.854mg.kg-1.
However, there was no significant difference when control was compared with the
sole rumen digesta application and humanure and rumen digesta combinations and
also when the sole rumen digesta application was compared with humanure and
rumen digesta combination of 5 + 5t.ha-1 and when the humanure and rumen digesta
combinations were compared with one another. This shows that with the addition of
humanure there is an increase in the nickel level in the soil while there was no effect
when rumen digesta was added. Sole humanure treated plots recorded nickel
concentration higher than the permissible limit while the rest of the treatments
recorded values much lower than the 6.5 mg.kg-1 recommended limits.
3.1.4 Copper (Cu):
The result of the effect of treatment on soil Cu reveals that there was
significant difference when control was compared with the treatments and when the
treatments were compared with one another. The sole humanure application
recorded 1.75 mg.Kg-1 when compared with control. The sole rumen digesta and
humanure and rumen digesta combinations produced 4.25, 11.9, and 11.35
respectively when compared with control. The sole humanure application when
compared with the sole rumen digesta application and humanure and rumen digesta
342 Ekpe et al., Effect of Organic Waste…
combinations produced 2.5, 10.15, and 9.6 mg.Kg-1. The sole rumen digesta
application recorded 11.6 and 7.1 mg.Kg-1 when compared with the humanure and
rumen digesta combinations. Nevertheless, there was no significant difference when
the humanure and rumen digesta combinations were compared with each other. This
shows that there is an increase in soil Cu level with the addition of rumen digesta
and humanure. The concentration of cupper in the soil as a result of the treatments
fell above the permissible concentration in the soil. The soil native concentration was
equally higher than permissible limit of 1.5 mg.Kg-1
3.2. Effects of Treatments on Cucumber Growth Parameters.
The effect of humanure, rumen digesta, and humanure and rumen digesta
combinations on cucumber yield, yield and growth parameters are presented in table
2.
Table 2: Effect of Treatments on Cucumber Yield, Yield and Growth
Parameters.
Note: Figures with the same super scripts are not statistically significant while
figures with different superscript are significant.
3.2.1. Number of Fruits:
The result of the effect of treatment on number of fruits shows that there was
significant difference when the number of fruits produced from the control was
compared with the sole rumen digesta application and when the other treatments
Treatment
No of
fruits.ha-
1
Vine
length
(cm)
No of
leaves
No of
branches
Leaf area
index(cm²)
T1
20,500ᵃ
74.6ᵃ
51.9ᵃ
1.1ᵃ
95.4ᵃ
T2
42,000b
86ᵃ
21.8ᵃ
1.6ᵇ
114.6ᵃ
T3
84.500c
94.2b
21.9ᵇ
1.8ᶜ
117.8
T4
40,000d
76.9ᵃ
20.4ᶜ
1.3ᵈ
110.9ᵃ
T5
40,000e
83.3ᵃ
20.2ᵈ
1.6ᵉ
105.2ᵃ
F-LSD(0.05)
10.0
18.2
1.2
0.02
NS
343 Ekpe et al., Effect of Organic Waste…
were compared with one another. The sole humanure application produced 21,500
fruits when compared with the control while the control produced 64,500 less number
of fruits than sole rumen digesta treatment. Also there were 2000 more fruits in both
5 + 5 t.ha-1 humanure and rumen digesta combinations when compared with control.
Ten tons per hectare rumen digesta treated plots produced 44500 each more fruits
than 5 + 5 and 10 +10 t.ha-1 humanure and rumen digesta combinations. The higher
number of fruit yield from the rumen digesta treated plots showed the superiority of
this soil amendment in improving the growing medium of the plants. The humanure
amendment also proved superior to the control and their combinations at 5 + 5 and
10 +10 t.ha-1.
3.2.2. Vine Length:
The result of the effect of treatment on the vine length shows that there was
no significant difference when the control was compared with the treatments and
when the treatments were compared with one another. Nevertheless, there was
significant difference when the sole rumen digesta application was compared with
control. This supports the strong indication that rumen digesta is playing soil
enrichment role for cucumber growth and its general yield.
3.2.3. Number of Leaves:
The result of the effect of treatment on number of leaves reveals that there
was significant difference when control was compared with the treatments and when
the treatments were compared with one another. The sole rumen digesta and
humanure and rumen digesta combinations produced 5.9, 1.4 and 1.6 respectively
when compared with control. The sole humanure application when compared with
the sole rumen digesta application and humanure and rumen digesta combinations
produced 5.9, 1.4, and 1.6. The sole rumen digesta application recorded 4.5 and 4.3
when compared with the humanure and rumen digesta combinations. Nevertheless,
there was no significant difference when the sole humanure application was
compared with control and when the humanure and rumen digesta combinations
were compared with each other. This shows that there is an increase in number of
leaves of cucumber when rumen digesta was added and not much effect when
humanure was added.
344 Ekpe et al., Effect of Organic Waste…
3.2.4. Number of Branches:
The result of the effect of treatment on number of branches reveals that there
was significant difference when control was compared with the treatments and when
the treatments were compared with one another. The sole humanure application
produced 0.2 when compared with control. The sole rumen digesta and humanure
and rumen digesta combinations produced 0.7, 0.5, and 0.2 respectively when
compared with control. The sole rumen digesta application and humanure and
rumen digesta combination of 5 + 5t/ha produced 0.5 and 0.3 when compared to the
sole humanure application. The sole rumen digesta application recorded 0.2 and 0.5
when compared with the humanure and rumen digesta combinations. The humanure
and rumen digesta combinations recorded 0.3 when compared with one another.
Nevertheless, there was no significant difference when the sole humanure
application was compared with humanure and rumen digesta combination of 10 +
10t/ha. This shows that there is an increase in number of branches with the addition
of rumen digesta and humanure.
4.0 Conclusion
It can be concluded that humanure and rumen digesta are good sources
of organic manure for crop production since they improve Aq soil physic-chemical
properties significantly and increased yield, yield and growth parameters of
cucumber. The best rate in terms of yield and growth parameters is the sole
humanure application.
5.0 Recommendation
Farmers within and outside Ihiagwa agro ecological zones are advised to
make use of humanure and rumen digesta. This will not only help in improving the
soil and crop yield but will also improve the environment and prevent pollution. The
residual effect should be to determine how long nutrients released from them can
last in the soil.
References
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345 Ekpe et al., Effect of Organic Waste…
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Jönsson, H., Stintzing, A.R., Vinnerås B. and Salomon, E., 2004. Guidelines on the
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