Volume 2 No.
12, December 2012 ISSN 2224-3577
International Journal of Science and Technology
©2012 IJST. All rights reserved
http://www.ejournalofsciences.org
A Descriptive Analysis of Rainfall for Agricultural Planning in Lokoja Local
Government Area of Kogi State, Nigeria.
Audu, E.B.
Government Secondary School, Lugbe, Along Umaru Musa Yar’adua Way, Abuja – FCT.
ABSTRACT
The ever - increasing anthropogenic activities which have led to global warming, climate variation and consequently, climate change
is altering rainfall characteristics / pattern across the globe, Nigeria inclusive. For this reason, this paper seeks to give a descriptive
analysis of rainfall in Lokoja Local Government Area (LGA), Kogi State; Nigeria with a view to offering useful suggestions for
proper agricultural planning in order to ensure food sufficiency. Daily rainfall of 1981 – 2010 (30 years) obtained from the Nigerian
Meteorological Agency, Oshodi, Lagos, Nigeria is used for this study. The rain days were also obtained from the Nigerian
Meteorological Agency, Oshodi, Lagos. Results are presented in tables and subjected to statistical analysis using measures of central
tendency such as mean, mean deviation and median; measures of dispersion such as range, variance and standard deviation as well as
a measure of relationship (coefficient of variance). The findings indicate that April and October are the onset and cessation months
(dates) of rains for the study area. Long – term mean annual rainfall is about 1216.83mm, while the mean rain days and long – term
monthly rainfall stood at 81.8mm and days respectively. The decadal mean rainfall and rain days are1263. 26mm and 81.9days,
minimum rainfall was recorded in 1982 (804.5mm), maximum was in 1999 (1767.1mm), range is 962.6mm, variance is 1, 400,
630.35, mean deviation is 35, 288.04, median is 1, 182.85mm, standard deviation is 1, 183.48 while coefficient of variance is
97.26%. These results indicate that the study area is still very favourable to crop farming despite the observed frequent dry spells. It
is therefore suggested that crops which can withstand longer days of absence of rainfall should be planted early such as melon.
Hybrid crops should be introduced while the use of irrigation should be given an aggressive attention in order to boost crop
production, ensure food security and alleviate poverty.
Keywords: Rainfall, agricultural planning, onset, cessation, food security and rain days.
I. INTRODUCTION variations in the onset and cessation of rains in Kaduna, Kano
and Sokoto, 1961 – 2007.
There are so many problems facing agriculture in Nigeria with
particular reference to Lokoja Local Government, Kogi State. In the field of agriculture, rainfall is the most important
Some of these problems include reduction in land area due to climatic factor in Nigeria [1]. This is because its onset ushers in
rapid urbanization, incidences of pests and diseases, poor soil planting season, its duration and distribution ensures crop
nutrients, rural – urban migration, poverty, use of crude tools as sustainability and favourable yield, while its cessation marks
well as unreliable rainfall among others. Of these problems, the harvesting and storing season. Whenever there is late onset,
most important is the climatic factor among which is rainfall [1]. hunger, temporal unemployment and poverty loom. Dry spells
and droughts which are related to rainfall and occur annually in
Living organisms (both plants and animals including man) Nigeria [3] [4] are injurious to crops leading to crop failure. The
cannot survival without optimum water supply. Although, it has early and late cessations also destroy the late crops [3]. [5]
been argued that rainfall (water) and temperature are the most Rainfall is one of the indices of agro – meteorological moisture.
important climatic determinants of crop survival and
production especially in Nigeria. However, generally; Every year, farmers in Nigeria are usually in high spirit to plant
temperature has remained favourable to crop production their crops in anticipation that yields would be favourable.
especially during the growing season, but rainfall is not only Though as it may, this is not usually the case as crop failure is
disappointing, but also erratic, highly unreliable and witnessed annually. This situation threatens food availability
unpredictable. The era in which rainfall was highly relied upon and security and leads to not only poverty, but also hunger
by farmers for sufficient crop production is gone. Meanwhile, among the farmers and other Nigerians who depend on them
Nigeria which still practices rain – fed agriculture rely on the for food. This eventually leads to shortage of food, increasing
“mercy of nature” to produce adequate food and the needed raw importation of “common” foodstuffs especially rice [6], hike in
materials for the few agro allied industries. [2] Apart from the the prices of foodstuffs, mal nutrition and so on.
socio - economic problems facing Nigerian farmers, climatic [7]
variability constitutes a major limiting factor in crop production The most critical weather and climate dependent sectors of
due to the practice of rain - fed agriculture. Due to changes in any West African and particularly Nigerian economy are
the characteristics of rainfall occasioned by global warming agriculture and water resources. Rainfall characteristics
which has led to rainfall variability, uncertainties surround the determine crop yield. Where rainfall is optimum, crop yield is
reliabilities of the onset, duration, cessation, total annual high; if low, low crop yield and if too high, poor yield partly
amount of rainfall, intensity and its general or favourable due to flooding [8]. In general therefore, optimum rainfall which
distribution across the growing season months. [3] There are is well distributed throughout the growing season is required
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Volume 2 No.12, December 2012 ISSN 2224-3577
International Journal of Science and Technology
©2012 IJST. All rights reserved
http://www.ejournalofsciences.org
for a good harvest, abundant food crops and availability of raw to this at present. The major means of transportation is by road
materials for the few agro – allied industries as well as to which leads to traffic congestion during the rush hours
guarantee food security. This is partly necessary so as to curb (mornings and evenings) and on Lokoja market days. The
the prevailing circumstance in which Nigeria which is a largest river in Nigeria, River Niger flows through Lokoja
tropical country faces acute food shortage annually to the LGA; but it is under – utilized for transportation and even
extent that huge sums of money is usually budgeted for the irrigation. On the other hand, due to the hilly nature of the area,
importation of foodstuffs, a situation which is becoming cable car and under – ground train are other possible means of
unacceptable to both the people and government of Nigeria. transportation.
II. OBJECTIVES OF THE STUDY
Global warming, climate variability and climate change have
adverse effect on the hydrological growing season and
consequently, crop production. This paper has the following
objectives:
i. to analyze the attributes of rainfall in the study area,
ii. to determine the suitability of rainfall for agricultural
policy, planning and implementation; and
iii. to suggest measures of complementing rainfall for
adequate crop production so as to ensure food security
The Study Area
The study area, Lokoja LGA; which is expanding and
increasing in population at alarming rate, is located between
latitudes 7o461N - 7o521 and longitudes 6o381E – 6o481. Lokoja
derived its name from two (2) Hausa words, a tree and a colour.
“Loko”, which means “Iroko” and “ja”, which means red. So,
the name Lokoja means, Red Iroko (tree). Kogi is also a Hausa
word which means a river. Lokoja is the Headquartres of Fig. 1: Map of Kogi State showing the Study Area
Lokoja LGA, the Capital of Kogi State and the confluence
town of not only Kogi State, but also Nigeria. The area enjoys Lokoja LGA had a total population of 82, 483 in 1991 [10]. In
both wet and dry seasons with the total annual rainfall ranges 2006, the population of the LGA stood at 196,643 [11]. Lokoja
between 1000mm – 1500mm. Mean annual temperature is LGA comprises of many ethnic groups such as the Hausa,
about 27.7oc and a relative humidity of 30% in dry season and Nupe, Kupa, Kakanda, Oworo, Ganagana, Bassa and Egburra.
70% in wet season [9] [10]. Average daily wind speed is 89.9
km/hr. Wind speed is usually at its peak in March and April. III. MATERIALS AND METHOD
Average daily vapour pressure is 26 Hpa [9]. The most
important hydro – geological feature is the River Niger and the Daily rainfall data of 1981 – 2010 (30 years) were used for this
confluence of Rivers Niger and Benue [9]. At Lokoja, there is a study. The data were obtained from the Nigerian
wide flood plain along the River Niger, which is more than Meteorological Agency (NIMET), Oshodi, Lagos. Results are
1,600m wide [9]. This flood plain is intensively used for dry presented in tables to aid quick understanding. The data were
season farming (okra, tomatoes, sweet potato, vegetables and subjected to statistical analysis using measures of central
maize), fishing site, a grazing field for cattle in dry season and tendency such as mean, mean deviation and median; measures
recreation. of dispersion such as range, variance and standard deviation as
well as a measure of relationship (coefficient of variance). The
Lokoja LGA falls within the Precambrian age as well as the aim of this is to look at the characteristics of rainfall in the area.
various sedimentary rocks [9]. It is also found in Guinea
Savanna with the presence of gallery forest along water courses IV. RESULTS AND DISCUSSION
[9]
. The land rises from about 300m along the Niger valley to
between 300 – 900m above sea level in the uplands [9]. The
The results of this study are presented in tables 1 – 5.
dominant primary activities are fishing, farming, trading,
hunting with low percentage of tertiary activities [9]. The area is
another tourist haven in Nigeria, but only little attention is paid
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Volume 2 No.12, December 2012 ISSN 2224-3577
International Journal of Science and Technology
©2012 IJST. All rights reserved
http://www.ejournalofsciences.org
Table 1: Annual Rainfall, Mean and Rain days, 1981 – Table 3: Monthly and Mean Monthly Rainfall (mm),
2010 (30 years) 1981 – 2010 (30years)
Year Total Rainfall Mean (mm) Rain days Month Rainfall Mean
(mm) January 33.1 1.1
1981 1144.6 95.4 88 February 241.2 8.0
1982 804.5 67 53 March 661.3 22.0
1983 853.7 71.1 60
1984 1147.7 95.6 80
April 3128.7 104.3
1985 965.7 80.5 84 May 4698.3 156.6
1986 1281 106.8 87 June 5081.9 169.4
1987 1170.8 97 71 July 5988.5 199.6
1988 1330.9 110.9 88 August 6120.1 204.0
1989 1519.7 126.6 91 September 6443.7 214.8
1990 1136.3 94.7 92 October 4003.7 133.5
1991 1492.7 124.4 98 November 87.1 2.9
1992 1083.1 90.3 82 December 17.1 0.6
1993 995.6 83 73
1994 1194.9 99.6 93 Total 36,504.7 101.4
1995 1291.1 107.6 91 Source: Author’s computation (2012).
1996 1240.7 103.4 80
1997 1410.5 117.5 83 Table 4: Monthly and Mean Monthly Rain days,
1998 1031 85.9 80 1981 – 2010 (30 years)
1999 1767.1 147.3 90
2000 1010.7 84.2 71
2001 1003.8 83.7 77
Month Rainfall (mm) Mean (mm)
2002 1276 106.3 90 January 07 0.23
2003 923.6 77 73 February 17 0.57
2004 1335.4 111.3 84 March 68 2.27
2005 939.4 78.3 72 April 117 3.9
2006 1684.1 140.3 87 May 284 9.47
2007 1501.4 125.1 98 June 335 11.17
2008 1239.5 103.3 73 July 412 13.73
2009 1653.3 137.8 83
August 421 14.03
2010 1076.1 89.7 82
September 423 14.1
October 273 9.1
November 36 1.2
December 0.1 0.033
Source: Author’s computation (2012) * Rain days were
Total 2, 393.1 79.8
obtained from NIMET, Oshodi, Lagos.
Table 2: Simple Measures of Rainfall Variability in Source: Author’s computation (2012).
Lokoja, 1981 – 2010
Table 5: Decadal Mean Rainfall and Rain days (mm),
Statistics Values 1981 – 2010 (30 years)
N 30
Minimum 804.5mm
Year Rainfall Mean Rain days
Maximum 1767.1mm
Range 962.6mm 1981 - 1990 1135.49 79.4
Mean 1216.86mm 1991 - 2000 1251.74 74.3
Median 1, 182.85mm 2001 - 2010 1263.26 81.9
Mean Deviation 35,288.04mm
Variance 1,400,630.35
Standard Deviation (SD) 1,183.48 Source: Author’s computation (2012).
Coefficient of variability (CV) 97.26
Considering tables 1 and 2, the mean rainfall is 1216.86mm.
Even though the numbers of years with rainfall below the mean
Source: Author’s Computation (2012) from table 1. are equal to the number of years above it, the values of those
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©2012 IJST. All rights reserved
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above the mean are very alarming especially 1989, 1991, 1997, with the period of severe drought which ravaged the country
[15]
1999, 2006, 2007 and 2008 which could lead to flooding and . The effect of these droughts reflected in the mean for that
erosion [3] [12]. This confirms global warming in the study area. decade, but did not affect the number of rain days (see
Also, this abnormal rainfall could be harmful to the type of appendix 1) which therefore means that the total annual rainfall
crops grown in the area. Arguably, the surplus rainfall above may not determine the total number of rain days. On the other
the annual total and long – term mean for the station could be hand, rainfall increased from the first decade to the third decade
said to be near decadal. The annual rainfall at the station which confirms the meteorological effect of global warming at
favours the growing of cereals and root crops such as rice, the study area.
millet, groundnut, cassava, yam and so on as well as cattle
rearing since it is sufficient to provide adequate surface water V. CONCLUSION & RECOMMENDATIONS
especially during the wet season and the growth of grasses.
Further, the number of rain days (table 1) is more favourable
for single cropping and unsuitable for double cropping except a From the fore – going, despite the fact that climate is changing;
shorter duration crops (hybrid) and / or the use of irrigation. rainfall duration and rain days are still very favourable for
This does not support adequate food supply throughout the agricultural activities in the study area. Although, late onset,
year. The minimum rainfall is 804.5mm which occurred in early cessation, fluctuation / deficit in annual total as well as
1982 and corresponded with the drought period in Nigeria. The dry spells are very common at the station. Therefore, it is
highest rainfall of 1767.1mm occurred in 1999. The mean expected that farmers should be advised on the annual dates of
deviation which is above the mean for the study area, median, onset and cessations of the rains (April and October), crops to
variance, range, standard deviation which are large and the CV be planted early such as melon which can withstand long period
of 97.26% also confirms rainfall variability, although low. of absence of rains, hybrid cropping as well as the use of
August and September recorded the highest rainfall while the irrigation. Irrigation is very important not only due to high
highest rain days occur in July, August and September unpredictability of the rains and frequent dry spells [3] [16], but
(tables 3 & 4). also to support all – year - round cropping so as to ensure
steady food supply [17] for the ever – growing population of not
Table 3 shows the monthly and mean monthly rainfall and only the study area, but also Nigeria at large. This would ensure
indicates that April is the ideal month for planting (onset) and food security and aid poverty alleviation in view of the fact that
October is the cessation (harvesting period) due to rainfall majority of Nigerians are farmers. It is unfortunate that Nigeria
sufficiency. The long – term mean is also favourable for the still practices rain - fed agriculture. Countries that produce
earlier mentioned crops. [14] The onset of rain is the month in surplus food for consumption, industries and export have
which accumulated total rainfall is in excess of 51mm, while transformed agriculture from traditional to modern
the cessation is the date after which no more than 51mm of the (mechanized). China, Israel, Java Island, Thailand, India, just to
rain is expected. Based on this, month with a long – term mean mention a few are good examples. A nation which still depends
rainfall totaling 102mm and above marks the onset and on traditional agricultural practices would not only face scarcity
cessation of rains respectively. So, for Lokoja LGA, the months of food, high cost of foodstuffs, inadequate raw materials for
of April and October mark the onset and cessation of rains. agro – allied industries and unemployment, but would also be
poor due to high importation of foodstuffs and experience
Table 4 shows total rain days which agree with monthly and economic insecurity. [18] Hot climate and little rain are
mean monthly rainfall in aspects of the onset and cessation of experienced in the extreme northern states of Nigeria where
rains at the station, that is, April and October respectively. The desertification is fast encroaching on arable lands and
mean rain days are also favourable to crop production. The agriculture is highly dependent on irrigation. Again, if
long – term mean monthly rain days can also be used to irrigation is properly practiced in Nigeria especially in dry
determine the onset and cessation of rains. Long – term season, abundant and quality crops would be harvested due to
monthly mean rain days up to half or greater than the long – abundant sunlight for high temperature and photosynthesis.
term annual mean could be regarded as the onset and cessation Nigeria therefore, needs to rise up towards the
of rains. The number of years to be considered should not be commercialization of agriculture and agricultural produce in
less than thirty (30) years [14].Therefore, the months of April order to bring back the loss glory and the era in which
and October mark the onset and cessation of rains for the study agriculture was the back bone of its economy. A country which
area. can produce enough food for local consumption is a wealthy
nation. Agricultural policies should be more realistic and
Table 5 shows the decadal rainfall which agrees with the annual achievable. More Agricultural Research Institutes should be
and long – term mean hence favourable to agriculture. In the established not only in the study area, but also in the entire state
first decade (1981 - 1990), rainfall is less than the mean for to develop hybrid crops, establish more scientific and research
1981 – 2010 (30 years) because the station witnessed a decline farms as well as embarking on seminars to enlighten the
in rainfall in 1982, 1983, and 1985. 1982 and 1983 coincided farmers on the current trend in farming system. Meteorological
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International Journal of Science and Technology
©2012 IJST. All rights reserved
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services should also be localized in the area. In addition, mixed on Meteorology, its Application and Challenges in 21st
farming should be emphasized and encouraged so as to reduce Century. Volume 3, No. 2, August, 2002. Pg. 82.
the rate at which farmers wait endlessly for the government to
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the negative effect of chemical fertilizers on human health as a Variation of Annual Rainfall Amount, Onset,Termination
result of the chemicals used in manufacturing them though and Duration of the Rainy Season in Katsina State of
chemical fertilizers aid mass production of crops. Nigeria. In Geo – Studies Forum. An International Journal
of Environmental & Policy Issues. A Publication of the
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