Variations in Climatic Parameters and Food Crop Yields: Implications on Food Security in Benue State, Nigeria.

Transcription

1 Kogi State University From the SelectedWorks of Confluence Journal of Environmental Studies (CJES), Kogi State University, Nigeria Spring October 15, 2012 Variations in Climatic Parameters and Food Crop Yields: Implications on Food Security in Benue State, Nigeria. Emmanuel Adamgbe Fanan Ujoh Available at:

2 Variations in Climatic Parameters and Food Crop Yields: Implications on Food Security in Benue State, Nigeria Emmanuel M. Adamgbe 1 and Fanan Ujoh 2 Abstract Agricultural production in Nigeria like in other developing countries is highly vulnerable to variations in climatic parameters which may have inverse or direct effect on the performance of food crops. This paper examines the patterns and trends of the variations in the climatic parameters and the implications of such variations on efficient yield rates of some food crops in Benue State using data on climatic variables (rainfall, temperature, sunshine) and the yield of some crops per hectare for 25 years ( ). Data on the climatic variables were collected from the Nigerian Meteorological Agency, AirForce Base, Makurdi while the data on food crop yields were collected from Benue State Agricultural and Rural Development Authority (BNARDA), Makurdi. Data were analyzed using multiple correlation and time series analysis. Results show that the climatic parameters and food crops were characterized by high inter-annual variability. All the climatic parameters except rainfall amount, temperature and sunshine were on downward trend together with rice and maize. The joint effect of the climatic parameters on the yield of all the crops varies between 78% (Yam) and 36% (Groundnut). Among the seven climatic parameters, sunshine and rain days have the highest influence on the yield of all the seven crops while dates of onset and duration have the least influence. The implications of the findings on agricultural development and food security in Benue State have been highlighted. Keywords: Variations, Climatic Parameters, Trends, Patterns, Crop Yields and Implications. Introduction Nigeria is an agrarian country with about 70% of the population engages in agricultural production at a subsistence level despite the fact that the country depends heavily on the oil industry for its budgetary revenues (National Report, 2006). Agricultural holdings are generally small and scattered. Traditional smallholders, who use simple techniques of production and the bushfallow system of cultivation, account for around two-thirds of Nigeria's total agricultural production. Nigeria's wide range of climate variation allows it to produce a wide variety of food and cash crops. However, food production is low and has not kept pace with population increase as reflected in the increasing levels of food importation and undernourishment (Federal Bureau of Statistics, 2009). 1. Department Of General Studies, Akperan Orshi College Of Agriculture, Yandev, Nigeria. adamgbeem@gmail.com 2. Department Of Geography & Environmental Management, University of Abuja, Nigeria. fananujoh@yahoo.com More so agriculture in Nigeria is mostly rain-fed, with the decreasing rainfall across Nigeria many rural dwellers are left with no other option than to migrate to cities for unavailable jobs; a condition which is having its tolls on Nigerian cities. Indeed, many Nigerian cities are now going through a process of urban decay due to the menace of overcrowding. This scenario poses challenges of insecurity on national development that can largely be resolved through improved food production. There are many factors influencing crop production including soil, relief, climate, low capital base of farmers, pests and diseases, among others. Nevertheless, climate is the most important factor that influences agricultural production (Efe, 2009). According to Ayoade (2004), agriculture largely depends on climate to function, hence, precipitation, solar radiation, wind, temperature, relative humidity and other climatic parameters affect and solely determine the global distribution of crops and livestock as well as their productivity (yields). The concept of climate and agriculture has been extensively discussed. For example, Lema (1978), Oguntoyinbo (1986), Ayoade (2004) and Cicek and Turkogu,

3 (2005) have all confirmed that climatic parameters (i.e. rainfall, sunshine, temperature, evaporation, etc) are closely interrelated in their influence on crops. In fact, in Nigeria variations and changes in climatic parameters can have significant impacts on agricultural production, forcing farmers to adopt new practices in response to altered conditions (Bryant, 1997). It is therefore submitted that climate is one of the major elements that influence agricultural productivity, however, the extent of these is not mostly shown. More so, several studies on crop-climate relations have been reported in different parts of Nigeria (see Akintola, 1983; Showemimo, 2002; Tyubee, 2006; and Adamgbe, 2012) and the results of these studies indicate that climatic effects vary among crops and regions in Nigeria. Nieuwolt (1977) also confirms this position for other parts of the tropical region. Consequently, in a large country like Nigeria with different climatic regions, studies of crop-climate relations are important towards government s programmes on revitalizing the agricultural sector of the economy. Moreover, in the recent past, Benue State which is regarded as the Food Basket of the Nation has attracted a lot of agricultural projects/schemes that require detail findings on the implication of the climatic parameters for their effective design, planning and implementation. This study is therefore, aimed at contributing to the understanding of the trend and patterns of the climatic parameters and their effect on the yield of crops in Benue State, Nigeria. Study Area Benue State lies between latitudes I and I N, and on longitudes I and I E in the central part of Nigeria called 'Middle belt' (Nyagba, 1995). The State shares boundary with Nassarawa State to the north, Taraba to the northeast, in the south by Cross River, while in the southwest is Enugu, Ebonyi and Kogi State to the west. A short international boundary with the Republic of Cameroon is shared around Kwande Local Government Area (Figure 1). Climatically, the State belongs to the Koppen's Aw climate group and experiences tropical wet and dry seasons. The rain falls for seven months from April to October with total annual amount ranging between 12,000-20,000mm while dry season sets in November and ends in March (Nyagba, 1995). Temperatures are constantly high averaging between C and sometimes rising to 37 0 C especially within Makurdi the state headquarters. The elevation, which is generally undulating, rises from the Benue valley below 100m eastwards and southwards to the western ranges of Cameroonian highlands and Nsukka escarpments respectively. Benue State is drained by River Benue and its tributaries such as Katsina-Ala, Okpokwu, Guma, Gwer, and Aya. The dominant soil in the state is the tropical ferruginous which is generally low in organic matter, bases and cation exchange capacity (Nyagba, 1995) Adamgbe $ Ujoh. Published by the Department of Geography and Planning, Kogi State University, Nigeria

4 Benue State lies within the root and grain crops zone of Nigeria with great potential of for commercial for commercial production of yam, cassava, sweet potato, soya beans, sorghum, beans, cowpea, millet maize, rice, beniseed and groundnut. Agriculture in the State is still dominated by the use of rudimentary farming equipments such as hoes, axes, and cutlasses. It is characterized by small farm systems, low capitalization, low yields per hectare and peasant ownership of livestock production (Surma, 1995 cited in Tyubee, 2006). Materials and Methods The data used for the study were archival data on rainfall (mm), Temperature (0 0 C), sunshine (hours) and crop yields (tones/hectare) for a period of 25 years ( ). The data on crop yields were obtained from the official records of the Benue State Agricultural and Rural Development Agency (BNARDA). The data has been reportedly collected from farmers in Benue State through surveys. The crops selected for the study were mainly food crops whose yields were documented by BNARDA. These include cassava, yam, maize, rice, sorghum, groundnut, and soya beans. Rainfall, temperature and sunshine data were obtained from the Nigerian Meteorological Agency (NIMET), AirForce Base, Makurdi. The choice of the climatic parameters was based on their importance in determining the time of farm preparations and planting, growth, development and yield of crops in West Africa (Howard and Oguntoyinbo, 1987). The choice of the weather station is in view of its capacity to serve the entire state and beyond. From the climatic data collected, the following parameters were computed: i. Onset of the rainy season (date(s)/days) ii. End of the rainy season (date(s)/days) iii. Duration of rainy season (days) iv. Number of rain days (days) v. Annual rainfall (mm) vi. Mean Monthly Temperature ( 0 C) vii. Mean monthly Sunshine (hours) The onset/end of the rainy season in the study area was computed from Walter s (1967) method because of its higher reliability among other methods (Bello, 1995). The method is expressed as: Date of Onset/End = DM (51 A)...(1) TM Where, DM= is the number of days in the month containing the date of Onset/End; A = is the accumulated total rainfall of the previous months; TM = is the total rainfall for the month in which 51mm or more is reached and 51mm = is the threshold of rainfall for both Onset/End month. However, because of the existence of shorter changes that are characteristic of tropical climates, the modified Walter s method by Olaniran (1983) was used. It defines the dates of onset and end of the rainy season respectively as that (Walter s onset or end of the rains date) which is not immediately followed or proceeded by dry spells of five or more duration. Duration of the rainy season was derived by counting the number of days between the onset date and the end date of the rains in a given year. A rain day is a period of 24 hours (10:00am 10:00am local time) with at least 0.3mm of recorded rainfall amount. Descriptive statistics were used in the preliminary processing of the data collected and to determine the coefficients of variability, Time series was used to determine the trend in the climatic parameters and yield of crops. Multiple and partial correlation analyses were employed to establish the relationship between the climatic parameters and crop yield; and also show the joint and single contribution of the climatic parameters in the yield of food crops in Benue state, Nigeria. Results and Discussion Variations in the Climatic parameters The extreme statistics of the variations in the climatic parameters from have been presented below. Table 1 revealed that the earliest date of onset of the rainy season was 2 nd April of the year 1999, while the latest date was 2 nd May of the year 1987 and the mean date was 16 th April. Also, table 2 shows that the earliest date of cessation of the rainy season was 1 st September of the year 2001 while the latest date was 16 th October of 1987 and the mean date of cessation was 10 th October. Similarly, highest duration of the rainy season was 194 days (2008), lowest duration was 139 days (2001) and the mean was 177 days. The highest number of rain days was 95 days (1999), lowest was 59 days and the mean duration was 77 days. The highest rainfall amount of mm occurred in 1999, the lowest amount was 841.1mm in 1988 and the mean was 2012 Adamgbe $ Ujoh. Published by the Department of Geography and Planning, Kogi State University, Nigeria

5 1208.1mm. The highest temperature was C (2010), the lowest was C (2002) and the mean was C. The highest number of sunshine hours was 6.9 hours (2009), the lowest was 5.4 hours (1987) while the mean was 6.18 hours (Table 3) Table 1: Extreme statistics of Dates of Onset of Rainy season in Benue State Parameter Earliest Year Mean Latest Year Date Date Onset 2 nd April th April 2 nd May 1987 Date/Days (91) - (106) (125) - Table 2: Extreme Statistics of Cessation Dates of Rainy season in Benue State Variable Earliest Year Mean Latest Year Date Date Cessation 1 st Sept th Oct. 16 th Oct Date/Days (244) - (283) (298) - Table 3: Extreme Statistics of Duration of Rainy Season, Annual Rain days, Rainfall Amount, Temperature and Sunshine Parameter Mean Highest Year Lowest Year Duration (Days) Rain days (Days) Annual Amount (mm) Temperature ( 0 C) Sunshine (Hours) Table 4: Extreme Statistics of Crop Yields (tonnes/ha) in Benue State Crop Mean Highest Year Lowest Year Cassava Yam Maize Rice Groundnut Soyabeans Sorghum Inter-annual variations in the Mean Yield of some food Crops Table 4 shows the extreme statistics of the yield of some food crops in Benue State from The highest yield of cassava per hectare (13.69) was in the year 1992 and the lowest (4.20) was in the year 1988 while the mean yield was The highest yield of yam (12.95) was in 2010 and the lowest (9.87) was in the 1987 while the mean yield was The highest yield of maize per hectare (2.50) was in 1988 and the lowest (2.40) was in 1997 while the mean was Also, the highest yield of rice per hectare (2.5) was in 1992, the lowest (1.07) was in 1987 while the mean was The yield of groundnut per hectare was highest (2.05) in 2010, the lowest (0.46) was in 1988 and the mean was Soya beans had the highest yield per hectare (2.76) in 1996 and the lowest yield (0.55) in 1987 while the mean yield was The highest yield per hectare of sorghum (1.79) was in 1994, lowest yield (0.56) was in 1987 while the mean yield was Variations in the Climatic Parameters and Crop yields Table 5 revealed that there was generally low inter-annul variability in the climatic parameters. However, among the seven climatic parameters studied, there was highest coefficient of variability in rainfall amount (17.6%), followed by rain days (9.6%) while the least was found in mean monthly 2012 Adamgbe $ Ujoh. Published by the Department of Geography and Planning, Kogi State University, Nigeria

6 Adamgbe & Ujoh. Con. J. Envtal Stds, 2012, 7:59-67 temperature (1.7%). In terms of the yield of the crops studied, the highest coefficient of interannual variability was found in maize (55.1%), followed by groundnut (36.5%) while the least was found in Yam (7.5). There were however, generally higher coefficients of variability in the yield of the crops, compared to the climatic parameters. This can be attributed to the combine impact of the climatic parameters, other climatic factors and non climatic factors on the yield of the crops. Trend in the Climatic Parameters and Yield of Some Food Crops The trend in the climatic variables revealed that dates of onset and end of the rainy season, duration of the rainy season and rain days were on downward trend (fig.2). This implies that dates of onset and end of rainy season have been decreasing as time progresses. Meanwhile, rainfall amount, mean annual temperature and mean annual sunshine were on an upward trend (fig. 3, 4 and 5). This implies that they had been increasing as time progresses. On the other hand, among all the crops studied, cassava, yam, groundnut, sorghum and soya beans were on upward trend while rice and maize were on downward trend (fig. 6 and 7). This shows that with increasing temperature, sunshine and excessive rainfall the yield of maize and rice decreases. This agrees with the findings by Nguyen, (2006) that a higher temperature causes the yield of rice and some other crops to decline. Table 5: Coefficient of Variability of the Climatic Parameters and Crop Yields Study Variables Onset End Duration Rain days Annual Amount Temperature Sunshine Cassava Yam Maize Ground nut Soya Beans Sorghum Rice Standard Mean Deviation Coefficient of Variability (%)

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8 Adamgbe & Ujoh. Con. J. Envtal Stds, 2012, 7:59-67 Joint Effect of the Climatic Variables on Food Crop Yields The joint effect of the climatic parameters on the yield of the selected food crops in Benue State from is shown in table 6. The result showed that the seven climatic parameters (onset and end of the rains, duration of rainy season, rain days, annual amount, temperature and sunshine) jointly accounted for 78% of variance in yam yield, about 71% of variance in cassava and sorghum yields, 60% of variance in soya beans yield, 49% of variance in maize yield, 48% of variance in rice yield and 36% of variance in groundnut. The results of the F-test analysis also showed that there are correlations between the climatic parameters and crop yields. This is because the F- test value of all the crops is less than the table value (Table 6). Single Effect of Climatic Factors on the Yield of Food Crops The single effect of the climatic parameters is shown by the partial coefficients of determination presented in table 7. Among the seven climatic parameters studied, sunshine exerts the highest influence on the variances of all the crops ranging from 68% (yam) to 16% (groundnut) yields. Rain days are an important factor for yam, cassava and maize accounting for 60%, 40% and 31% of the inter-annual variations of their yields respectively. In addition, rainfall amount contributes (35%) and 24% to the variations of cassava and maize yields.

9 Temperature and end dates of the rainy season contributes 32% each to the variations in rice and sorghum yields respectively while onset and duration of rainy season accounts for 18% and 10% of the variance in sorghum and ground nut yields respectively. The high correlation of the climatic parameters on the yield of some crops suggests that these climatic parameters are the most critical factors other than non climatic factors such as pest and diseases, shortage of farm inputs as well as other socio-economic factors. Table 6: The Joint Effect of Climatic Parameters on Crop Yields (tonnes/ha) in Benue State Crops Multiple Coefficients Calculated Table F-test of Determination F-test Value Value at 0.05 Cassava Yam Maize Rice Groundnut Soya beans Sorghum Table 7: Partial Coefficients of Determination showing the single effect of Climatic Parameters on Crop yields in Benue State Climatic Ground Soya Parameters Cassava Yam Maize Rice nut Beans Sorghum Onset End Duration Rain days Annual Amount Temperature Sunshine Conclusion and Recommendations The result of the study has clearly revealed that climatic parameters play a central role in the yield of some food crops in Benue State. Essentially, the climatic parameters have variable pattern and trends which accounts for the variations in the yields of some food crops in the State. Consequently, to sustain (and possibly improve on) crop production and yields in Benue State so that the state maintain its position on the agricultural map of Nigeria, BNARDA should be resuscitated for better performance in extension services to farmers and weather monitoring in Benue State.. In view of the high correlation of crop yields with climatic parameters, and the increasing rainfall amount with decreasing rain days, soil conservation measures and correct cultural practices should be adopted to prevent soil erosion and conserve soil moisture. Plant breeding should be encouraged to develop improved crop varieties that can thrive in the face of changing climatic conditions. Furthermore, Smith, (2000) observed that diversification of income sources is an adaptation strategy including off farm employment which has the potential to reduce vulnerability to climate related income loss. Lastly, 2012 Adamgbe $ Ujoh. Published by the Department of Geography and Planning, Kogi State University, Nigeria

10 there are needs for the establishment of standard Weather Stations in rural areas in the state. This will enhance climatic data collection and it will facilitate agricultural planning and sustainable development. References Adamgbe, E.M. (2012): Effect of Rainfall Variability on Maize Yield in Gboko L.G.A. of Benue State. Unpublished M.Sc. Dissertation submitted in the Department of Geography, Benue State University, Makurdi. Akintola, J.O. (1983): An Analysis of the Effects of Agroclimatic Factors on Food Crop Yields in Ibadan Area of Oyo State. Unpublished Ph.D Thesis, University of Ibadan. Ayoade, J.O. (2004): Introduction to Climatology for the Tropics. Revised edition. Spectrum books limited, Ibadan. Bello, N. J. (1995): On Reliability of the Methods of Predicting the Onset and Cessation of the Rains in a Tropical wet-and-dry Climate: Ondo as a Case Study. Journal of the Nigerian Meteorological Society, 1(1): Bryant, E. (1997). Climate processes and change. Cambridge, UK: Cambridge University Press, 45. Cicek, I. and Turkogu, N. (2005): Urban effects on precipitation in Ankara Turkey. Atmosfere 18 (3): Efe, S.I. (2009): Climate Change and Food Security in Africa: Delta State Nigeria Experience: In Anyadike, R.N.C., Madu, I.A. and Ajaero, C.K., (2010): Conference Proceedings on Climate Change and the Nigerian Environment held at UNN. F.O.S. (2009): Federal Office of Statistics Review of the Nigerian Economy FOS, Abuja, pp150 Hayward, D. and Oguntoyinbo, J.S. (1987): The Climatology of West Africa. Barnes and Neble Books, Totowa, New Jersey. Nguyen, N.V. (2006): Global Climate Changes and Rice Food Security FAO, Rome. Nieuwolt, S. (1982): Tropical Climatology: An Introduction to the Climates of the Low Latitudes. John Wiley and Sons. Pp 207 Nyagba, J.L. (1995): Geography of Benue state. In Denga, D.I. (ed) Benue State, A Compendium. Aboki Publishers, Makurdi, Benue State. Oguntoyinbo, J.S. (1987): Climate Variability and Food Production.West African Geographical Journal, 5(2): Oguntoyinbo, J.S. (1986): Climatology in A. Youdeowei, Ezedinma, F.O.C and Onazi, A. (eds) Introduction to Tropical Agriculture Longman. Essex. Olaniran, O.J. (1983): The Start and End of the Growing Season in the Niger River Basin development Authority Area of Nigeria, Malaysian Journal of Tropical Geography, Vol. 9. pp Showemimo, F.A. (2002): Influence of Climatic Variations on Some Agro-nutritional Traits of Quality Protein Maize lines in Northern Guinea Savanna of Nigeria. Journal Tropical Biosciences, 2 (1): Smith, O. (2000): Adaptation to Climate Change in Agriculture workshop proc. Canadian Agri-Food Research Council, Ottawa pp Tyubee, B.T. (2006): An Analysis of Food Crop Yields and Climate Relations in Benue State, Nigeria. Journal of the Nigerian Meteorological Society. Vol. 6 No. 1 Walter, W.M. (1967): Length of the Rainy Season in Nigeria, Nigerian Geographical Journal, Vol. 10, No. 2, pp Lema, A.J. (1978): An assessment of water availability for maize in lower Moshi. Journal of Geographical Association of Tanzania National Report (2006). Nigeria. International Conference of AgrarianReform and Rural Development. Ports Alegre 7-10 March, ISSN: Cite this article as: Adamgbe, E.M. and Ujoh, F. (2012). Variations in Climatic Parameters and Food crops Yields: Implications on food Security in Benue State, Nigeria. Con. J. Envtal. Stds, 7: Adamgbe $ Ujoh. Published by the Department of Geography and Planning, Kogi State University, Nigeria