CHEMICAL PROPERTIES OF SOIL, YIELD AND N, P, K UPTAKE BY
OKRA AS AFFECTED BY COMMERCIALLY PRODUCED ORGANIC
BASED FERTILIZERS.
1
OLOWOKERE, F. A., 1AJUFO, C. A. AND 1OJOWA, F. D.
1
Department of Soil Science and Land Management, Federal University of Agriculture, Abeokuta,
Nigeria
ABSTRACT
Organic based fertilizer production is on the increase in Nigeria. A green house study was carried
out at the Federal University of Agriculture, Abeokuta in 2011 to study the effects of four
commercially produced fertilizers namely: neem organo compound (NF), sunshine organo
mineral (SF), providence organo mineral (PF) and Gateway (GF) Fertilizers on the growth, yield,
nutrient uptake of okra and soil chemical properties. The fertilizers were applied at the rate of 10
t/ha and arranged in a completely Randomized Design. Parameters measured were: plant height,
number of leaves, yield and N, P, K uptake. Post planting soil was also analyzed for nitrogen,
phosphorus and potassium. Results showed that NF promoted okra yield and potassium uptake.
Post planting soil nitrogen, phosphorus and potassium were significantly (p<0.05) higher than
the control with the application of gateway, sunshine and neem organo compound fertilizers. It is
recommended that okra should be planted with neem organo compound and sunshine
organomineral fertilizers for improved yield and better soil quality.
Key words: Organo compound, Organo mineral, Providence, Gateway, Nutrient uptake
Corresponding author: Olowokere, F. A. Email: olowoflo@yahoo.com; funluv.97@gmail.com
Tel. +2348033965860
INTRODUCTION
Organic fertilizers have been reported to increase the yield and quality of crops as well as soil
properties. Production of organic based fertilizers help to convert wastes which would otherwise
become a nuisance to the environment to environmentally friendly and agriculturally useful
materials. Different raw materials which could be of plant or animal origin are used for the
production of these fertilizers, these could be used solely or in combination. Their efficiency will
depend on the type of raw materials used for the preparation. Examples of raw materials used for
the production of the organic based fertilizers are: neem plant/seed, poultry manure, saw dust,
rice husk, city refuse, cow, pig dung, crop residues e. t. c. It is therefore necessary to compare the
effects of commercially produced organic based fertilizers so as to ascertain their efficiencies.
Few sources of commercial organic fertilizer was reported by Adeoye, 2005. Organic farming is
on the increase as a result of the activities of organic bodies like National Organization of
Organic Agriculture Network (NOAN), Government agencies like Ladoke Akintola University
(Mustapha et. al., 2011), Organic Agriculture Project in Tertiary Institutions in Nigeria
(OAPTIN) and West African Network of Organic Agriculture (WANOART) With improved
awareness of organic agriculture in the country, organic agriculture is now being practiced at a
large scale level in Nigeria. Commercial production of organic based fertilizers becomes relevant
under large scale farming because the time required for preparation of these fertilizers will be
reduced if they can be purchased in large quantity and such times could be used for other
activities on the farm. Some of the commercial organic based fertilizers are produced to be crop
specific, i. e. the specific nutrients required by a particular crop would have been included in the
course of preparation. Materials with additional properties could also be included in the
fertilizers. Therefore, it is necessary to compare the efficiency of some of the commercially
produced fertilizers in Nigeria.
MATERIALS AND METHODS
The screen house experiment was carried out at the Screen house of College of Plant Science and
Crop Production (COLPLANT), Federal University of Agriculture, Abeokuta. The University
falls within longitude 3° 37´ N and 7° 68´ E. Twelve top soils (0-15 cm) were weighed into 15
litre buckets which have been perforated underneath with saucers. \The organic based fertilizers
used were: Sunshine organo- mineral, Gateway organic, neem organo compound and Providence
organic fertilizers produced by the Ondo State Government, Ogun State Government, National
Research Institute for Chemical Technology, Zaria and Olaku Industries Nigeria Limited,
Abeokuta respectively. The fertilizers were applied at the rate of 10t/ha which translated to
53.57g/pot by thoroughly mixing it with the soil, the control soil was without fertilizer. the
treatments were arranged using Completely Randomized Design and replicated six times. The
soil was watered to field capacity every day. Okra (variety- NHAE 47-4) obtained from the
National Horticultural Research Institute, Idi-Isin, Ibadan, Oyo state Nigeria was planted at the
rate of three seeds per pot at two weeks after fertilizer application. These were thinned to one
seedling per pot at two weeks after planting.
DATA COLLECTION
Data collection started at three weeks after planting and was done weekly for four weeks, the
following parameters were assessed: Plant height with the aid of a ruler, number of leaves by
physical counting. Okra fruits were harvested at three days interval.
PLANT SAMPLING
Okra plants were cut at the soil level at eight weeks after planting, these were oven dried at 65°C
to constant weight and milled for analysis.
PLANT AND SOIL ANALYSIS
The milled plant sample was analyzed for nitrogen by Kjeldahl method, phosphorus by vanado
molybdate method (Juo, 1982). and potassium by flame photometry. Nutrient uptakes were
determined by multiplying dry matter weight by nutrient contents. At the end of the experiment,
soil in each pot was thoroughly mixed and sub-sampled for analysis. Nitrogen was determined
by Kjeldahl method (Bremner, 1996), particle size by hydrometer method (Udo and Ogunwale,
1986), pH by glass electrode method while organic carbon was by Walkley Black wet oxidation
method (Nelson and Sommers, 1989). Available phosphorus was extracted by Bray 1 extraction
method (Bray and Kurtz, 1945) and P solution was determined using the molybdenum blue color
method (Murphy and Riley, 1962). Calcium, magnesium and potassium were determined by
extraction with neutral 1 N NH4OAc, K in the extract was determined by flame photometry
while Ca and Mg were determined on atomic absorption spectrophotometer (AAS).
STATISTICAL ANALYSIS
Data obtained were subjected to the analysis of variance using SAS 2000 package, treatment
means were separated using Duncan’s Multiple Range Test (DMRT) at 5 % probability level.
RESULTS AND DISCUSSION
Results of the particle size distribution and chemical characteristics of pre-planting soil are
shown in Table 1. The soil is neutral, organic matter, phosphorus, nitrogen and potassium were
low while it is loamy sand in texture. Sunshine organo mineral fertilizer had the highest pH
(9.03), followed by this was Providence organic fertilizer (8.41), Gateway organic fertilizer
(7.50) while neem organo compound fertilizer had the lowest pH (7.07). Providence organic
fertilizer was highest in total nitrogen content (6.72 %) while Gateway fertilizer had the lowest
values (2.10 %). Gateway fertilizer had the highest phosphorus content while Sunshine organo
mineral fertilizer had the lowest P content (0.86 %). Neem organo compound and Sunshine
organo mineral fertilizers were highest in potassium and organic carbon respectively (Table 2).
TABLE 1: Particle Size distribution and Chemical Characteristics of pre-planting soil
Property
Value
pH
7.02
Organic matter (%)
0.79
Nitrogen (%)
0.13
Avail. P (mg/kg)
7.13
K (cmol/kg)
0.18
Ca (cmol/kg)
6.16
Mg (cmol/kg)
1.27
Particle Size
Sand (%)
77
Clay (%)
14
Silt (%)
9
TABLE 2: Chemical Properties of commercially produced organic based fertilizers used
for the experiment
Fertilizer
Property
pH (H2O)
N (%)
P (%)
K (%)
O. C. (%)
NM
7.07
3.24
3.28
2.73
37.69
GT
7.50
2.10
3.41
2.15
53.95
SH
9.03
2.13
0.86
0.84
76.74
PR
8.41
6.72
1.04
1.41
49.45
NM - Neem Organo Compound Fertilizer
GT – Gateway Organic Fertilizer
SH – Sunshine Organo-mineral Fertilizer
PR – Providence Organic Fertilizer
The heights of plants treated with Gateway fertilizer were highest throughout the duration of the
experiment, though no significant differences were observed (Table 3). The effect of different
commercially produced organic based fertilizers on the number of leaves of okra is shown in
Table 4. No significant effect was observed at 3, 5 and 6 weeks after planting while the highest
significant (p<0.05) number of okra leaves (6.17) when compared with the control was given by
plants with the application of Sunshine organo mineral fertilizer and the lowest value (4.17) was
observed on the control. Increase in the number of okra leaves as a result of organo mineral
fertilizer application has been reported by Ayeni et. al., 2012 and Olaniyi and Oyerele, 2012.
Fertilizer application did not have any significant effect on nitrogen and phosphorus uptake by
okra, while plants treated with neem organo compound fertilizer took up significantly (p<0.05)
higher level of potassium in comparison with the control (Table 5). Highest potassium content of
neem organo compound fertilizer might have been responsible for this observation. A similar
trend was observed on okra yield, neem organo compound fertilizer application also significantly
(p<0.05) increased okra yield to 46 g/pot above the control. The trend of okra yield in relation to
fertilizer application is as follow: NM> SH> PR, GT > C (Figure 1). This may be due to the
pelleted form of neem organo compound fertilizer which might have controlled the rate of
nutrient release in the fertilizer, thereby making nutrient release slower than the others. The
effect of commercially produced fertilizers on the nitrogen, phosphorus and potassium content of
post-planting soil is shown in Table 6. Gateway organic fertilizer application significantly
(P<0.05) increased the nitrogen content (0.16 %) of post planting soil when compared with the
control, this value is however not significantly different from the ones for other fertilizers. All
the fertilizers with the exception of Gateway organic fertilizer significantly (P<0.05) increased
the phosphorus and potassium contents of post planting soil above the control. The highest P
value 947.41 mg/kg) was observed in plots with the application of Sunshine organo mineral
fertilizer. Percentage increase in P content over the control by the fertilizers followed this order:
SH (69.6%) > PR (65 %) > GT (39.65 %) >NM (22 %). The order of increase in K content was:
NM > SH > PR > GT > C. The highest Phosphorus content was obtained on plots with sunshine
organo mineral fertilizer application. the highest K value obtained from neem organo compound
plots may be due to the fact that the fertilizer had highest K content.
CONCLUSION
The result of this study shows that neem organo compound fertilizer increased the yield and
quality of okra while sunshine organo mineral fertilizer increased the number of leaves. all the
organic based fertilizers improved the quality of soil. Okra could be planted with gateway
organic, sunshine organo mineral, neem organo compound and providence fertilizers for
improved yield, crop and soil qualities. However, it is recommended that this work has to be
repeated on the field before making conclusion.
TABLE 3: Height (cm) of okra as affected by different types of commercially organic based
Fertilizers.
Treatment
3 WAP
4 WAP
5 WAP
6 WAP
Control
12.43
16.57
24.42
SH
15.45
20.57
28.67
39.00
PR
14.73
18.43
27.50
35.40
NM
14.08
19.62
25.75
39.30
GT
15.82
21.38
29.38
40.42
NS
NS
NS
NS
NM - Neem Organo Compound Fertilizer
GT – Gateway Organic Fertilizer
SH – Sunshine Organo-mineral Fertilizer
PR – Providence Organic Fertilizer
WAP- Weeks After Planting
NS – Not Significant
33.67
TABLE 4: Effect of Different Commercially Produced Organic based Fertilizers on the
number of okra leaves.
Treatment
3 WAP
4 WAP
5 WAP
6 WAP
NM
5.17
5.83ab
6.67
7.33
SH
5.0
6.17a
7.17
7.83
PR
4.67
5.83ab
7.33
7.67
GT
4.17
5.50ab
6.17
8.00
Control
4.17
4.17b
6.50
7.00
NS
NS
NS
Means along a column with the same letter(s) are not significantly different from each other at
P<0.05
NM - Neem Organo Compound Fertilizer
GT – Gateway Organic Fertilizer
SH – Sunshine Organo-mineral Fertilizer
PR – Providence Organic Fertilizer
WAP- Weeks After Planting
NS – Not Significant
TABLE 5: N, P and K uptake by okra grown with commercially produced organic based
Fertilizers.
Treatment
N uptake (mg/kg)
P uptake (mg/kg
K uptake (mg/kg)
GT
15.00
2.21
26.46ab
SH
28.29
2.50
27.21ab
NM
33.50
1.82
40.10a
PR
14.25
0.95
26.21ab
Control
14.36
1.75
12.33b
NS
NS
Means along a column with the same letters are not significantly different from each other at
p<0.05
NM - Neem Organo Compound Fertilizer
GT – Gateway Organic Fertilizer
SH – Sunshine Organo-mineral Fertilizer
PR – Providence Organic Fertilizer
WAP- Weeks After Planting
NS – Not Significant
50
a
45
40
Fruit yield (g/piot)
35
ab
ab
30
ab
25
20
b
15
10
5
0
Control
NM
Treatment
SH
PR
GT
Figure 1: Effect of different commercially produced organic based
fertilizers on okra yield.
NM - Neem organo compound Fertilizer, SH- Sunshine organo-mineral Fertilizer
TABLE 6: Nitrogen, phosphorus and potassium content of post planting soil as affected by
different types of commercially produced organic based fertilizers.
Treatment
N (%)
P (%)
K (%)
GT
0.16a
23.86c
0.16d
SH
0.13ab
47.41a
0.36b
NM
0.13ab
18.47d
0.43a
PR
0.13ab
41.30b
0.27c
Control
0.12b
14.4e
0.15d
Means along a column with the same letters are not significantly different from each other at
p<0.05
NM - Neem Organo Compound Fertilizer
GT – Gateway Organic Fertilizer
SH – Sunshine Organo-mineral Fertilizer
PR – Providence Organic Fertilizer
WAP- Weeks After Planting
NS – Not Significant
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