Modeling Rainfall As a Constraining Factor for Cocoa Yield in Ondo State Ajayi I
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AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH © 2010, Science Huβ, http://www.scihub.org/AJSIR ISSN: 2153-649X doi:10.5251/ajsir.2010.1.2.127.134 Modeling rainfall as a constraining factor for Cocoa yield in Ondo State Ajayi I. R.1, Afolabi M.O.1, Ogunbodede E.F.2 and Sunday A.G.1 1Department of Physics and Electronics, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria. 2Department of Geography and Planning Science, Adekunle Ajasin University, Akungba- Akoko, Ondo State, Nigeria. ABSTRACT Rainfall is undoubtedly a determining agro-meteorological factor in the cultivation and production of cocoa. This work has revealed that rainfall has a constraining ability on cocoa yield in the core cocoa production areas of Ondo state, Nigeria. It was also established that cocoa production is in its best in areas like: Idanre, Ondo, Akure, Ile-Oluji, Owo e.t.c, which have yields above 1000MT per annum and rainfall lesser than 51.30mm. Cocoa yield was also shown to be the inverse of annual rainfall level. This was evident as cocoa yield increased in the early and latter months of the year when the rains are yet to fully come, and suffered in the mid year at the heart of raining season. A model of rainfall as it affected cocoa yields was achieved in this work. Keywords: Yield, cocoa producing areas, sustain, location, constraining. INTRODUCTION improve their livelihoods, Nigerian farmers are not in any way exempted. Efforts are made to sustain Cocoa is generally conceived by most people to cocoa production in the cocoa growing regions mean a brownish powder used in the production of through public-private partnerships such as chocolate and is also sometimes interchanged for International Institute of Tropical Agriculture’s (IITA) cocoa tree. The cocoa tree, though native to the Sustainable Tree Crops Program (STCP). The World Americas, may have had a larger range of cultivation Cocoa Foundation (WCF) has reached over 300,000 in the past. Cacao (or Cocoa) trees grow in a limited small scale cocoa farmers together with their families geographical zone, of approximately 20 degrees to in its regional programmes in West Africa, Latin the north and south of the Equator. Nearly 70% of the America and Southeast Asia. Graduates of WCF- world crop is grown in West Africa (Cocoa Bean, supported farmer field schools report income http://www.ehow.com/cocoa-beans/). improvements of 22–55 percent or more, through Nigeria was ranked 4th in the world production of improved cultivation and marketing practices. cocoa in 2004. Nigeria was able to produce 0.37 million metric tons of cocoa, which amounted to In the Nigerian scenario, research sponsored by the 10.28% of the world cocoa production that year. See National Space Research and Development Agency table 1.1. The world cocoa production is on the scale (NASRDA) on Sustainable Optimum Cocoa of 3 million tons every year. Production in Ondo State, the chief cocoa producing state in the country, is on-going. The NASRDA Table 1.1: World Cocoa Production in 2004 support for cocoa research is not only intended to Country Production (million metric tons) provide the needed information on good production Cote d’Ivoire 1.33 practices, but also aims at discovering modern Ghana 0.74 techniques that will optimize cocoa production. It is Indonesia 0.45 also to further determine the combination of weather Nigeria 0.37 parameters (collected in situ) that can produce Brazil 0.17 optimal yield of cocoa from various sampling Cambodia 0.13 locations. Ecuador 0.09 Source: UN Food & Agriculture Organisation (FAO) Cocoa (Theobroma cacao L.) remains a major export in Nigeria. In its report in 1998 the Central Bank of As Cocoa farmers in many countries lack information on production and marketing practices to help them Nigeria that “a revenue of 7459.3 million Naira (US$ 53,280 at 140 per US$) was derived from dried cocoa Am. J. Sci. Ind. Res., 2010, 1(2): 127-134 beans (half of the income attributed to the total export where GPS reading, Elevation, and Soil temperature of major agricultural products)”. “Cocoa was first were taken and recorded. The soil type and cultivated in the western region of Nigeria in 1890” vegetation were also mechanically determined and (Adegeye, 1996). Its cultivation gained prominence recorded for each of the farmlands visited. See table rapidly in Nigeria such that by 1965, Nigeria became 1.2. the second largest producer in the world (Adegeye, 1996). The cocoa producing states lie within the Garmin’s manufactured hand-held Global Positioning rainforest zone of Nigeria which includes Ondo, System GPS (Model - GPS76) receiver with a built-in Ogun, Oyo, Ekiti, Edo, Delta, Cross-Rivers and Quad Helix antenna, and Wide Area Augmentation Akwa-Ibom; with over 50% of the total quantity of System (WAAS) capable, of a good accuracy was cocoa produced for export or utilized locally per used for collection of co-ordinate data i.e. Longitude annum comes from Ondo State (Adegeye, 1996). and Latitude in the farmlands. At every sampling The production, however, has declined in recent point, the GPS receiver after it was powered on, years; a fact attributed partly to poor soil quality initializes and starts acquiring satellites. The GPS (Ajobo, 1980; Egbe, 1989). receiver remains in this mode until it has acquired at least three satellite signals. But after acquiring at Crop production involves a complex interaction least four satellite signals, the receiver enters into the between the environment, soil parameters, and 3D GPS Location where the information is provided nutrient dynamics (Ukpong and Moses, 2001). by the GPS on current position and altitude in the Failure to understand these complexities has resulted farmland. The sampling location was therefore in lack of good crop production and management recorded at this stage. This aided in GIS cocoa techniques; hence agricultural production has tended farmland map classification. to be low. “It is well known that cocoa production is highly sensitive to changes in climate, from length The rainfall classification was carried out using the and intensity of sunshine, to rainfall and water Inverse Distance weighted (IDW) interpolation application, soil condition and temperature due to method. Surface interpolation is any formal technique evapotranspiration effects.” (Anim-Kwapong, et al, that uses values at sampled locations to predict 2008) In other words, agro-meteorological values at un-sampled locations. Inverse Distance elements—Temperature, Rainfall, Humidity, Weighted (IDW) interpolation implements a basic law Vegetation, soil organic matter content, Porosity and of geography—things that are close to one another Permeability could greatly ‘or partly’ act as are more alike than things that are far apart. To constraining factors for cocoa production hence, the predict a value for any unmeasured location, IDW need for a thorough study to be carried out on these uses the measured values surrounding the prediction environment-dependent factors. location. Those measured values closest to the prediction location have more influence on the In this research work attempt was made to determine predicted value than those that are farther away, the effects which rainfall—an agro-meteorological hence the name ‘inverse distance weighted’. IDW element has on the cocoa producing areas of Ondo assumes that each measured point has some local state, Nigeria in relation to the cocoa yield from the influence that diminishes with distance. This method sampled farmlands in the areas. was used for interpolation in the analysis. Sampling, Materials and Methods: A total of 17 RESULTS sampling locations—cocoa farmlands, which are located within the cocoa producing local governments The results as collected from the sampled farmlands of Ondo State were visited. Data were collected from is as shown in table1.2, it shows the location of each each of these sampling locations, and a uniform farmlands visited, elevation and the soil type and sampling method was used in all. At each sampling vegetation observed in these areas. Due to absence location, the GPS reading of three randomly-chosen of a meteorological station on the farmlands, the points around the farmland were taken and recorded. relevant local government rainfall and yield data A soil point was strategically chosen within the farm (tables 1.3 a – c & 1.4 a – b) were collected at the Ministry of Agriculture, Akure in Ondo state, Nigeria. 128 Am. J. Sci. Ind. Res., 2010, 1(2): 127-134 Table 1.2: Meteorological factors as recorded from the sampled cocoa farmlands Sampling Sampling S/N Soil Type Latitude Longitude Vegetation Elevation(m) Locations Crop 1 Ikpemen Cocoa Highly Laterized soil 7º 15′ 04.90″ 5º 35′ 57.8″ Tropical rain forest 287.5 2 Ago-panu Cocoa Sandy soil 7º 17′ 19.60″ 5º 36′ 59.6″ Savannah 260.3 3 Okeluse Cocoa Sandy soil 6°47' 49.00″ 5°35'16.6″ Tropical rain forest 110.2 4 Ute Cocoa Dark loamy 6°52' 12.90″ 5°36'20.7″ Tropical Rain forest 101.3 5 Arimogija Cocoa Dark loamy 6°49' 19.30″ 5°41'40.2″ Tropical Rain forest 78.4 6 Ipele Cocoa Highly Laterized soil 7°03' 14.80″ 5°40'53.5″ Savannah 178.5 7 Igbara-oke Cocoa Sandy soil 7°22' 47.30″ 5°03'1.90″ Tropical rain forest 343.3 8 Ilara-mokin Cocoa Sandy soil 7°20' 41.50″ 5°06'7.00″ Tropical rain forest 340 9 Ibule-soro Cocoa Sandy soil 7°19' 04.10″ 5°06'49.4″ Tropical rain forest 383.9 10 Uso Cocoa Sandy soil 7°15' 28.50″ 5°25'9.10″ Tropical rain forest 326.6 11 Ogbese Cocoa Sandy soil 7°14' 03.00″ 5°22'57.7″ Tropical rain forest 304.5 12 Oba-Akoko