Effect of Farmyard Manure and Nitrogen Fertilizer Rates on Growth, Yield and Yield Components of Onion (Allium cepa L.) at Jimma, Southwest Ethiopia
Kokobe W. Yohannes,
A field experiment was conducted at Jimma University College of Agriculture and Veterinary Medicine research field from October 2011 to March 2012 under irrigation to assess the response of onion to farmyard manure and nitrogen fertilizer rates. The study consisted of four levels of FYM (0, 15, 30 and 45 ton FYM ha-1) and four levels of nitrogen (0, 50, 100 and 150 kg N ha-1). The experiment was arranged in 4x4 factorial arrangements in a randomized complete block design with three replications. Data on growth, yield and quality parameters were recorded and analysed using SAS Computer Software version 9.2. Results revealed that interaction of FYM and N fertilizer significantly (p<0.05) influenced Plant height, number of leaves, leaf length, maturity, average bulb weight, total yield, marketable yield; harvest index and bulb dry matter. However, leaf diameter, bulb length, bulb diameter and unmarketable yield were not affected by the combined application of FYM and N fertilizer. The findings highlighted that the performance of onion at Jimma area can be enhanced through application of FYM and N fertilizers. The highest bulb yield of onion (36.85 ton ha-1) was obtained when the plots received combined application of 100 kg ha-1of N and 45 ton ha-1 of FYM which significantly increased the total bulb yield by about 53% as compared to the unfertilized plot (17.45 ton ha-1). This however, was statistically similar with the combined application of 150 kg ha-1of N and 30 ton ha-1of FYM and also150 kg ha-1 of N and 45 ton ha-1 of FYM. In this study, maximum dry bulb yield of onion (33.30 ton ha-1) was obtained when the plots received combined application of 150 kg ha-1 of N and 30 ton ha-1 of FYM. Therefore, from statistical point of view and labour requirements to prepare and apply FYM, a combined application of FYM at 30 ton ha-1 and nitrogen fertilizer at 150 kg ha-1 rates can be considered optimum for obtaining high onion bulb yield at Jimma area.
Received: November 19, 2013;
Accepted: February 13, 2014;
Published: April 18, 2014
Onions contribute significant nutritional value to the human diet and have
medicinal properties and are primarily consumed for their unique flavor or for
their ability to enhance the flavor of other foods (Randle,
2000). Onions benefit from high soil fertility as they have limited root
systems. Organic manure, compost or chemical fertilizers, provide nutrients
for producing of high yield and quality bulb. The amount of manure and/or fertilizers
applied however, depends on soil fertility level of the specific area.
Nitrogen is the principal plant nutrient required in much greater quantities.
It is the important component of proteins, enzymes and vitamins in plants and
is a central part of essential photosynthetic molecule, chlorophyll (Marschner,
1995). Plants demand for N can be satisfied from a combination of soil and
fertilizer N to ensure optimum growth. While exogenous N application is known
to increase yield of onions, many researchers on the other hand, found that
high levels of nitrogenous fertilizer resulted in reduced onion storage life
(Kato et al., 1987), cause delay in bulb maturity
and results in bolting, which is undesirable characteristic of onion (Aliyu
et al., 2008).
Though, onions are more susceptible to nutrient deficiencies than most crop
plants because of their shallow and unbranched root system (Brewster,
1994), application of chemical fertilizers alone generate several deleterious
effects to the environment and human health and they should be replenished in
every cultivation season because the synthetic N, P and K fertilizer are rapidly
lost by either evaporation or by leaching in drainage water and causes dangerous
environmental pollution (Aisha et al., 2007).
In addition, continuous usage of inorganic fertilizer affects soil structure
and those fauna found in the soil. Hence, organic manures can serve as alternative
to mineral fertilizers as reported by Naeem et al.
(2009) for improving soil structure (Ajayi et al.,
2008) and microbial biomass (Suresh et al., 2004).
With the increased cost of inorganic fertilizers, application of recommended
dose is also difficult to be afforded by the small and marginal farmers. Hence,
renewable and low cost sources of plant nutrients for supplementing chemical
fertilizers and that are affordable to the majority of farming community need
to be used. In this context, integrated nutrient management would be a viable
strategy for advocating efficient use of chemical fertilizers with matching
addition of organic manures and bio fertilizers (Tandon,
1987). Farmyard manure is a conspicuous organic component of an integrated
nutrient supply system, which improves soil health, increases the productivity
and releases macro and micronutrients (Kale et al.,
Onions are grown widely during the wet and dry seasons. However, yields are
much higher during the dry season because of fewer incidences of pests and diseases.
Due to this, in recent years, dry season production of onion is in the increase
in different parts of the country. Farmers in Jimma area (Southwest Ethiopia)
are aware of the response of onion to the applied nutrients and raise the crop
in homesteads using farmyard manure, household wastes etc. However, the rate
of farmyard manure and its combined effect with inorganic fertilizers for high
production of the crop is not well known. Currently little research has been
done on integrated use of organic and inorganic fertilizers application pertaining
to yield and yield related components of onion. In view of this fact, a systematic
investigation of the effect of using commercial fertilizer like nitrogen and
locally available, accessible and affordable farmyard manure is of paramount
importance for improving yield and quality of onion bulb.
This experiment was therefore initiated with the objective of assessing the
effects of combined use of different levels of Farmyard manure and Nitrogen
fertilizer on growth, yield and yield components and hence to identify optimum
combination of farmyard manure and nitrogen fertilizer which could give an economic
yield of onion in the study area.
MATERIALS AND METHODS
Description of the study area: The experiment was conducted at Jimma
University, College of Agriculture and Veterinary Medicine research field in
the year 2011/2012 under irrigation. The area is geographically located 346
km southwest of Addis Abeba at about 7°, 33'N latitude and 36°, 57E
longitude at an altitude of 1710 m.a.s.l. The mean maximum and minimum temperatures
are 26.8 and 11.4°C, respectively and the mean maximum and minimum relative
humidity are 91.4 and 39.92%, respectively (BPEDORS, 2000).
The mean annual rainfall of the area is 1500-1800 mm (Melaku,
Experimental design and treatments: The experiment consisted of four
levels of Farmyard manure (0, 15, 30 and 45 tons ha-1)
and four levels of Nitrogen (0, 50, 100 and 150 kg N ha-1)
and was set up in 4×4 factorial design arranged in RCBD
with three replications.
Seedlings of onion cultivar called Bombay Red were raised on a
seed bed of 1×5 m following the recommended agronomic procedures. Different
rates of well decomposed manure was carefully prepared and thoroughly applied
as a single application into the experimental plots, watered and left for one
week before transplanting (Olufolaji, 1990). Healthy
and vigorous seedlings of 12-15 cm height (at 3-4 true leaf stage) were carefully
uprooted from a seed bed prepared for this purpose and transplanted at a spacing
of 20×10 cm between rows and plants, respectively. The different levels
of N were applied in the form of Urea (46% N) in two split doses of equal amounts
at a time of transplanting and one and half month after transplanting. Recommended
cultural practices were uniformly applied for all treatment combinations.
Data on growth, yield and quality parameters were recorded and subjected to
Analysis of Variance (ANOVA) using SAS computer software version 9.2 (FAO,
2008). When ANOVA showed significant differences, mean separation was carried
out using Least Significant Difference (LSD) test at 5% significance level.
RESULTS AND DISCUSSION
Mean number of leaves per plant was significantly (p<0.05) affected by combined
application of N and FYM (Fig. 1). The highest mean value
(15.44) was obtained from the combined application of 150 kg ha-1
N and 45 ton ha-1FYM and the lowest mean value
(7.86) was recorded in the control treatment. This treatment increased the mean
number of leaves by about 49% as compared with the unfertilized plots.
Similar results were reported by Nasreen et al.
(2007), who found that application of 120 kg N ha-1 significantly
increased the number of leaves per plant, but further increase of N supply to
160 kg ha-1 tended to decrease it.
|Interaction effect of farmyard manure and nitrogen fertilizer
on leaf Number per plant of onion at Jimma
Vachhani and Patel (1993) also reported the highest
number of leaves per plant at the application rate of 150 kg ha-1.
The increase in number of leaves per plant with increase in N level can be due
to nitrogen that might have contributed in producing new shoots and vigor in
vegetative growth which is directly responsible in increasing the leaf number.
Application of N and Farmyard manure highly significantly (p<0.001) influenced
leaf length. But, their interaction was not significant. Increasing the level
of FYM application from 0-45 ton ha-1, increased
the mean leaf length per plant by about 28% when compared with the control (33.60)
(Table 1). Similarly, in this study application of N at different
levels showed a highly significant (p<0.001) effect on the mean leaf length
per plant (Table 1). The plots that were fertilized with the
maximum rate of N (150 kg ha-1) showed about
16% increase in mean leaf length per plant over the control (35.70 cm) which
is statistically at par with value (42.05) registered from plots that received
only 100 kg of N ha-1. Further application
of N above 100 kg ha-1 did not bring change
on mean leaf length onion.
The result is in agreement with Bungard et al.
(1999) who reported that N is the major constituent of proteins and the
presence of abundant protein tends to increase the size of the leaves and ultimately
increase carbohydrate synthesis. Kumar et al. (1998)
and Singh and Chaure (1999) also indicated that application
of N at 150 kg ha-1 gave the best result with regard to onion leaf
Application of Nitrogen and FYM did not significantly affect diameter of onion
leaves grown in this experiment (Table 1). The result was
not in agreement with those results reported by Kumar et
al. (1998). In their experiment the application of 150 kg N ha-1
gave the highest value with regard to leaf diameter of the longest leaf.
||Effect of farmyard manure and nitrogen fertilizer on leaf
length and leaf diameter of onion in Jimma
N: Nitrogen, FYM: Farmyard manure and
ns: Non significant at 5% level, Means followed by the same letter(s)
in the same column are not statistically significantly at 5% level of
This result is also in contrast with the finding of Suresh
et al. (2004) who reported that numerically higher leaf width was
observed with treatment receiving FYM at 100% and lowest leaf width while the
lowest value was obtained at a recommended dose of fertilizers used as a control.
However, the application of N and FYM fertilization did not indicate any significant
change on this response variable in this experiment probably due to the nature
of the variety used.
The level of farmyard manure and interaction with nitrogen did not significantly
influence mean bulb length of onin plant. This is because of the fact that nitrogen
is responsible for vegetative growth of plants and later it increases the bulb
weight through increasing bulb diameter rather than bulb length (Brewster,
1994). Although, FYM fertilization did not affect bulb length in this study,
a number of findings disclosed an increased bulb length in response to N fertilization
(Yadav et al., 2003; Reddy,
2005). But, separate application of N at different levels illustrated a
highly significant (p<0.001) effect on mean bulb length (Table
||Effect of farmyard manure and nitrogen fertilizer on bulb
length, bulb diameter and average bulb weight of onion in Jimma
|N: Nitrogen, FYM: Farmyard manure and ns: Non significant
at 5% level, Means followed by the same letter(s) in the same column are
not statistically significantly at 5% level of significancy
Of all the levels tested, the maximum rate of N (150 kg ha-1) increased
the mean bulb length by about 12% in reference to the control treatments (4.54
cm), which was statistically similar with the result obtained by the application
of 100 kg ha-1 N. The result indicates that further application of
nitrogen did not affect onion mean bulb length.
Nitrogen and Farmyard manure highly significantly (p<0.001) influenced the
mean bulb diameter of onion grown during this experiment. However, their interaction
did not show any significant effect. Application of FYM at a rate of 45 ton
ha-1 gave the highest mean bulb diameter (5.99
cm); which was statistically similar with 30 ton ha-1(Table 2). The smallest bulb diameter (5.59 cm) was
found at control (0 ton FYM ha-1).
In another study it was found that applications of farmyard manure, pelleted
manure, neem (Azadirachta indica) seed powder and karanj cake (Pongamia
pinnata) with 75% of the recommended inorganic fertilizer [100 kg ha-1
N, 60 ha-1 phosphorus (P) and 80 kg ha-1 potassium (K)]
resulted in increased onion bulb diameter compared with using inorganic fertilizers
alone (Mondal et al., 2004). Similarly, N fertilization
(150 kg ha-1) increased bulb diameter by about 8% in reference to
the control (5.47 cm), which may be linked to the increase in dry matter production
and allocation to the bulb. Larger bulb diameter in onion with N application
could be associated with promoting nature of nitrogen in cell elongation, above
ground vegetative growth and synthesis of more chlorophyll to impart dark green
color of leaves which may be linked to the increase in dry matter production
and translocation to the bulb (Brady, 1985).
A significant (p<0.05) interaction effect of nitrogen with farmyard manure
was also observed on mean bulb weight of onion. Mean bulb weight increase of
about 43% was obtained in response to application of 150 kg ha-1
N and 30 ton ha-1 FYM as compared to the control. But, additional
application did not bring any significant change. Likewise, mean bulb weight
of onion was highly and significantly affected by farmyard manure alone, where
the application of 45 ton ha-1 gave the maximum mean value (61.42
g) which resulted in 20% increases as compared to the control (Table
Abbey and Kanton (2004) found that application of
Farmyard Manure (FYM), Inorganic Fertilizer (IF) or a combination of manure
and inorganic fertilizer (FYM+IF) resulted in an increase of onion bulb weight.
The mean bulb weight improvement in response to N could be attributed to the
increase in number of leaves, leaf length and extended physiological maturity
in which case mean bulb weight showed significant and strong correlation with
each of these variables (Table 2). The increase in leaf number
and length resulted in an increase in assimilate production and allocation to
Significant interaction effect (p<0.05) of nitrogen and farmyard manure
was observed on plant height and total bulb yield of onion (Table
3). Application of 100 kg N ha-1 and 15 ton FYM ha-1
increased onion plant height by about 21% compared to the control (41.47 cm).
However, further increase of rate of fertilizer did not affect to plant height.
The highest mean plant height (54.16 cm) was obtained at 100 kg ha-1
N and 45 ton ha-1 FYM, while the lowest (41.47 cm) was obtained at
a treatment combinaton of 0 kg N ha-1 and 0 ton FYM ha-1(Table
3). The result is in line with the findings of Gupta
et al. (1999) who reported that application of FYM at 72.0 quintals
ha-1 along with ammonium sulphate at 565 kg ha-1 were
effective in increasing the growth and yield in onion. The mixture of these
fertilizers improved the vegetative growth characters of onion.
Increasing the application of combined level of N from 0 to 100 kg ha-1
and FYM from 0 to 30 ton ha-1 resulted in progressive
increase in total bulb yield of onion. Further increase in nitrogen and farmyard
manure fertilizer to 150 kg ha-1 and 45 ton
ha-1, respectively did not bring any difference.
The highest bulb yield of onion (36.85 ton ha-1)
was obtained when the plots received combined application of 100 kg ha-1
of N and 45 ton ha-1 of FYM which was statistically
similar with the levels of 150 kg ha-1 of N;
30 ton ha-1 of FYM and 150 kg ha-1
of N ; 45 ton ha-1 of FYM. This increased the
total bulb yield by about 53% as compared with the unfertilized plot (17.45
An integration of organic amendments with inorganic fertilizers resulted in
higher yields and greater growth than the inorganic fertilizer alone (Jayathilake
et al., 2002). In addition, the inclusion of organic manures and
bio-fertilizers reduced the required amounts of inorganic N, P and K required
for fertilization (Selvakumari et al., 2001).
||Interaction effect of farmyard manure and nitrogen fertilizer
on plant height, total bulb yield, marketable bulb yield and unmarketable
bulb yield of onion at Jimma
|N: Nitrogen, FYM: Farmyard manure, Means followed by the same
letter(s) within the same column are not significantly different at 5% level
||Pearson correlation (r) among growth, yield and yield components
|PH: Plant height, LNPP: Leaf number per plant, LL: Leaf length,
LD: Leaf diameter, BD: Bulb diameter, BL: Bulb length, TBY: Total bulb yield,
MBY: Marketable bulb yield, UMY: Unmarketable bulb yield ns: Non-significant,
*,** and ***Indicate significant difference at probability level
of 5, 1 and 0.1%, respectively
Highly significant (p<0.01) interaction effects were observed on marketable
yield (Table 3). But, no effect of the treatment combinations
was observed on the unmarketable bulb yield. The highest marketable bulb from
all the fertilizer combinations, treatments that had more amount of farmyard
manure fertilizer gave highest yield. On the other hand, the highest unmarketable
bulb yield was recorded from the unfertilized plots. In onion, low as well as
lack of nitrogen fertilizer may have been associated with early bulb formation,
stunted growth, with bulbs size and marketable yields reduced.
Highly significant (p<0.01) interaction effect of nitrogen with FYM was
also observed with respect to the harvest index (data not shown). The highest
harvest index (0.90) was recorded from treatment combination of 150 kg ha-1
N and 45 ton ha-1 FYM, which is not significantly
different from plots received 150 kg ha-1 N
and 30 ton ha-1 FYM. Increasing the level of
combined application of nitrogen and FYM from 0 to 150 kg ha-1
and 0 to 45 ton ha-1, highly significantly
increased the harvest index by about 36% over the respective control treatment.
Investigating correlations between the different response variables, it was
observed that plant height was significantly and positively correlated (Table
4) with leaf number per plant (r = 0.70***), total bulb yield (r = 0.62***),
marketable bulb yield (r = 0.62***) and bulb dry matter content (r = 0.38**).
This indicates that selection of fertilizer combination for high plant height,
results to the indirect selection of fertilizer combination for onion yield.
Onions are heavy feeders and require more fertilizer than is used in most vegetable
crops. The amount to be applied depends on the type and fertility status of
the soil. For economic production of the crop, this, however, requires identification
of optimum fertilizer: Organic, inorganic or their combination levels.Integrated
nutrient management is a viable strategy for promoting efficient use of chemical
fertilizers with some amount of addition of organic manures. In this experiment,
it was observed that main effect of FYM and N as well as their interactions
had considerable influence on plant height, number of leaves, average bulb weight,
marketable yield and total yield of onion. Leaf length, leaf diameter, bulb
diameter, bulb length and unmarketable bulb yield were not found responding
to the treatments. From this study, it was observed that 30 ton ha-1
FYM and 150 kg ha-1 N is the optimum treatment combination for onion
production in the study area.
The authors are gratefully indebted to Jimma University, College of Agriculture
and Veterinary Medicine for the financial support made to conduct this experiment.
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