Soil Fertility Evaluation for Cocoa Production in Southeastern Adamawa State, Nigeria

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1 World Journal of Agricultural Sciences 7 (2): , 20 ISSN IDOSI Publications, 20 Soil Fertility Evaluation for Cocoa Production in Southeastern Adamawa State, Nigeria 2 O.S. Ibiremo, M.A. Daniel, G.O. Iremiren and O. Fagbola Cocoa Research Institute of Nigeria, P.M.B. 5244, Ibadan, Nigeria 2 Department of Agronomy, University of Ibadan, Ibadan, Nigeria Abstract: In order to study suitability of soils of southeastern Adamawa state of Nigeria for cocoa production, a stratified-random sampling technique was used in taking soil samples up to 75 cm depth at Toungo and Ganye southeastern fringe of Adamawa state. Analytical results indicated that the soils in the area are sandy loam. The sand content ranged from gkg while the silt and the clay content ranged from and gkg soil respectively. The organic carbon at Toungo was and % and higher that those of Ganye Jagaba and Ganye Gurum- Pawo respectively. The total N at Ganye (Gurum-Pawo) and Ganye (Jagaba) averaged 0.04gkg while that of Toungo was 0.07 gkg. The available P at Ganye (Gurum-Pawo and Jagaba) was 6.98gkg soil while that of Toungo was 3.93 g/kg soil. From the results, nitrogen and phosphorus appear to be the most critical nutrients in the soils of the area and therefore would require an average of Kg urea ha and Kg SSP ha to bring up the nitrogen and phosphorus to levels required for cocoa production. The values of the nutrients obtained from the three sites are below the critical levels for most soil requirements for cocoa production. Key words: Soil fertility Evaluation Cocoa production Organic carbon Total N INTRODUCTION economic returns. Cocoa is a tap-rooted plant and requires deep well-drained soils, free from iron In Nigeria, cocoa is a major export crop with concretions, high in nutrient content and topsoil rich in revenue of at least 34 billion naira derived annually organic matter [3]. The Adamawa state Government from export of cocoa beans alone, besides revenue therefore commissioned the study of the soil along from cocoa by-product like butter, cake, liquor and Southeastern part of the state for possible cocoa powder []. Recently there has been policy shift of the production. The two local government areas investigated Nigerian Government to accord cocoa production which were Toungo and Ganye which are located toward the had been hitherto the mainstay of our economy the right ridges between Nigeria and Cameroon republic in the priority. The National Cocoa Development Committee southern fringe of the state. The objective of this work (NCDC) was established to provide agrochemicals at was to assess the fertility status of the soils of the areas subsidized rates for the control of pests and diseases for cocoa production. of cocoa to rehabilitee and regenerate old and unproductive cocoa plantations together with opening MATERIALS AND METHODS new farms and, sensitize and train farmers in the new technologies on cocoa production The federal The soils of Toungo (Longitude 2 E, Latitude 8 N) government funded these activities and this led to the and Ganye (2 E, Latitude 9 N) located towards the ridges cocoa producing states becoming proactive and between Nigeria and Cameroon Republic in the interested in expanding cocoa production. Smyth [2] southeastern part of Adamawa state were studied for their observed that unsuitable soil conditions, particularly physical and chemical properties (Fig. ). those of a physical nature this may not be amenable to The soil classified as Entisol [4], were formed from the improvement, may impose a limitation on production sedimentary rocks of sandstone, mudstone and shale. regardless of the quality of the planting material Generally, the soils are shallow and rocky. The area is used or the level of husbandry employed. This nearly level to gentle undulating plains with iron pans and implies that planting cocoa on unsuitable soils will few rock outcrops. The two sites have guinea savanna among other things leads to low productivity and poor vegetation. Correspoding Author: O.S. Ibiremo, Cocoa Research Institute of Nigeria, P.M.B. 5244, Ibadan. femiibiremo@yahoo.com. 28

2 World J. Agric. Sci., 7 (2): , 20 Fig. : Map showing the soil sampling sites in Admawa State, Nigeria Field Soil Sampling and Analysis: One site selected in at ph 7.0. The soil extract ratio was :6. Exchangeable K Toungo Local Government, was subdivided into three and Na in the extracts were read through the Jenway blocks (A, B and C) according to their position on the flame photometer (model PFP7) and Ca and Mg were read slope. Soil samples were taken using stratified-random on Atomic Absorption Spectrophotometer (AAS) sampling technique. In Ganye Local Government Buck Scientific 200A model. Exchangeable acidity was (Jagaba and Dallebi-Gurum-Pawo), site has plain to extracted with I N KCl and determined by titration with gentle slope in some few places. Soil samples were taken 0.05 N NaOH using phenolphthalein indicator while at 0 5, 5 30, 30 45, 45 60, 60 75cm using a soil the effective cation exchange capacity (ECEC) was by auger. They were air-dried, sieved in 2 mm sieve and summation method and percent base saturation was analysed according to standard analytical procedures [5]. calculated in follows: Particle size was determined by Bouyoucos hydrometer method, soil ph was measured in : soil-water ratio Exchangeable bases 00 % Base saturation = x using the EDT BA350 digital ph meter while organic ECEC carbon was determined by the wet digestion dichromate acid-oxidation method. Total N was determined using RESULTS AND DISCUSSION Kjeldahl digestion method and available P by Bray P method. This involved the addition of 5ml of 0.03 NHF In Toungo, all areas towards point B, top and 25ml of 0.5 N HCl to 460ml of water solution. of the slope are generally shallow in terms of depth 2 2 Exchangeable cations (Ca, Mg, K and Na ) were and maximum depth was less than 60 cm. A flood extracted with N ammonium acetate (NH OAc) buffered plain was encountered just before Maitani village. 4 29

3 World J. Agric. Sci., 7 (2): , 20 The width stretched up to 300 m while the length extended is very high while clay level is very low indicating low up to several kilometers. The moisture regime in all nutrient holding capacity. The soil is acid with an average sampling points except the flood plain had dry topsoil (0- ph of The organic carbon (O.C.), total N and 30 cm) and moist below 30 cm. Earthworm castes abound available P had average values of g/kg soil, 0.38g/kg in all the areas toward the flood plain, this indicates soil and 5.99 mg/kg soil respectively (Table ). All these optimum aeration. A lot of animal trampling was observed values are below critical values for cocoa. The in the area, which makes it necessary to practice deep exchangeable bases are adequate in concentration. tillage so as to break the soil crumbs. Within the The situation in site B is not different from block A. floodplain, the soils were poorly drained from the topsoil The soil is acidic with ph of 4.76 and is very sandy with to a depth beyond 60 cm. Mottles were observed down low clay content. Organic Carbon, total N and available the profiles within the flood plain beyond 60cm. The soil P are very low with average values of 0.76 g/kg soil, that is well drained is best for cocoa. Flooded or 0.04 g/kg soil and 6.99 mg/kg soil respectively (Table ). waterlogged soil does not give room for good root The exchangeable cations are adequate. development and exchange of gases. Hardy [6] and Smyth In block C the soil is very sandy with low clay, [2] both observed that excess of moisture and consequent while the ph is lower (4.69) than the other sites in shortage of oxygen inhibits root development of cocoa. Toungo. The organic carbon, total N and available P were The major limitation in Toungo site is depth of less than very low with average values of.30g/kg soil, 0.079kgkg 60cm in most places except few points along the soil and 2.8mg/kg soil respectively (Table ). These values floodplain. Cocoa requires a minimum depth of cm would support good cocoa production [9]. Fertilizer for a well developed and deep root system which will recommendations for cocoa according to the soil ensure a good anchorage against tropical storm and nutrient level indicated that the site has an average of adequate moisture supply during the dry season [7]. 0.06N equivalent to,200 Kg/ha and cocoa requires Although, Hardy [8] had earlier given a general rule of 0.2% N (i.e. 2,400 Kg/ N/ha). Assuming 0% availability.5m as minimum soil depth for optimum cocoa growth, 20 kg N/ha, the resultant difference will be supplied nevertheless, where all other aspects are particularly by Kg Urea/ha (5.33 bags). The soil P value is favourable soils only m deep may be acceptable. In block 5.09 mg P/kg soil (6P205/ Kg soil) at 0-5cm. When this A of Toungo, the soil is sandy loam and the level of sand value is subtracted from the critical value of 0mg P/kg Table : Physical and Chemical Characteristics of the project site at Toungo Chemical characteristics Physical characteristics Exch. Cations cmol/kg Sand Silt Clay g O.C Total N Avail. P Block Sampling Depth g/kg g/kg /kg ph g/kg g/kg mg/kg K 2 Ca 2 Mg Na 3 Al ECEC Base Sat. % A Mean B Mean C Mean

4 World J. Agric. Sci., 7 (2): , 20 Table 2: Physical and Chemical Characteristics of the project site at Ganye- Jagaba Chemical characteristics Physical characteristics Exch. Exch Organic Cations cmol/kg Acidity cmol/kg ECEC Sampling Sand Silt Clay Carbon Total Avail cmol/kg Base Block Depth g/kg g/kg g/kg ph g/kg N g/kg P mg/kg K 2 Ca 2 Mg Na H 3 Al soil Saturation% Ganye 0-5cm Jagaba Block A Mean Table 3: Physical and Chemical Properties of the project site at Ganye-Gurum-Pawo Chemical characteristics Physical characteristics Exch. Cations cmol/kg Sand Silt Clay g O.C Total N Avail. P ECEC Base Block Sampling Depth g/kg g/kg /kg ph g/kg g/kg mg/kg K 2 Ca 2 Mg Na 3 Al comlkg soil Sat. % A 0-5cm Mean B Mean C Mean Pilot Project site ECEC Effective Cation Exchange Capacity, O.C- Organic Carbon soil, 22.48kg P20 5/ha will supply the difference of.24mg low, with an average of g/kg across the soil depth P2O5 kg soil. The amount of SSP will be 24.89kg or while the ph is equally very low indicating acidity with 68.2kg Sokoto rock phosphate (2.5 bags). Potassium may an average range of across the various depths not be too necessary in this site as the value obtained considered (Table 2). Total N, organic C and available was just at the critical level. However, a little of about P have average values of 0.049g/Kg soil, 0.69g/kg soil 3kg Muriate of potash (MOP) could be applied per and 5.90mgP/kg soil across the soil depths respectively. hectare. All these fall below the critical level required for The soils of Ganye-Jagaba were averagely deep cocoa cultivation according to Smyth [2] and Wood [0]. compared with that of Toungo. Although, it was possible However, the levels of exchangeable cations such as K, to sample up to 90cm, this is still below the recommended Ca and Mg are adequate (Table 2). The fertilizer depth required for cocoa. The soil of the area is very recommendation for cocoa according to soil chemical heavy and poorly drained, as mottles were observed in characteristics in Ganye-Jagba revealed that the total the various depths of sampling. This area is not nitrogen value of the soil of this site at 0-5cm recommended for cocoa plantation. In Ganye-Jagaba, (plough layer) is 0.07% N equivalent to,400 KgN/ha. the soil is sandy loam. The clay content is extremely too The nitrogen requirement of cocoa is 0.2% N equivalent 22

5 World J. Agric. Sci., 7 (2): , 20 to 2,400 KgN/ha. 0% availability assumed 00kgN and cocoa requires 0-30 cmolkg soil. The difference would be required to be supplied. If urea is used as N between these values, converted to ppm, is 3.28ppm. source 222kg (4.44 bags) of it will be required to supply Therefore, 75.07kgha will be required to meet the the 00kgN/ha. The phosphorus value obtained was deficiency in this soil, which means 25.2 muriate of 5.3mgP/kg soil equivalent to.74 mg P20 5kg soil at 0-5cm. When this value was deducted from the critical level (0mg P/Kg soil) which is 22.9mg P205Kg soil, the difference between the critical level and the soil value was.6mg P205kg soil. The soil will require Kg/ha, which is obtainable from single super phosphate or Sokoto rock phosphate ( bag of either). No need for K fertilizer because the value obtained is adequate, 0.47 cmolkg soil. In Ganye-Dallebbi-Gurumpawo, the site is of plain to gentle slope in some few places. The site is deep compared with other two sites as samples could be taken beyond 90cm. The soils were well drained except some few spots along the valley bottom where mottles were observed in various depths. The soils were very sandy; this poses serious limitations in terms of moisture retention capacity. In addition, a small fringe along the surrounding mountains is very gravelly as a result of active weathering activities. This area is recommended for establishing cacao plantation. In block A, the amount of clay was 36gkg soil and average ph value was The average available P, total N and organic C content were 9.33 mgkg soil, 0.04gkg soil and 0.04 gkg soil respectively (Table 3). The soil in this site is very sandy; it shows it will hold less water and nutrients. Exchangeable bases were generally low compared with their critical values [9]. These could be regulated with addition of fertilizers. The clay content in block B was very low with an average of g kg soil and the sand is 634gkg soil. The soil is sandy loam. The ph is 5.03 and the value of available P was7.60 mgkg soil. Similar to block A, all the exchangeable bases were low. The average values for total N and organic carbon were 0.07g kg soil and 0.36gkg respectively. Site C has 4.6gkg clay while the sand is 726.2gkg soil, which means the clay is low while the sand content is very high. The average ph is The available P is 7.02 mgkg soil, which is far below the critical P level (Table 3). All exchangeable bases were low [7]. The average soil test values for total N in the area is 0.04% which translates to 800kgha with 0% availability giving 80kgNha. The N requirement of cocoa is 0.09% with 0% availability giving 240kg Nha. The difference of 60kgha can be supplied by addition of kg of urea ha (7.bags). The potassium is 0.2cmolkg soil potash ha (2.5 bags). Based on the classification of Smyth and Montgomery, [] soils of southwestern Nigeria were grouped into four main classes namely: good cocoa soils, fairly good soils, poor cocoa soils and very poor cocoa soils. The soils in two local government areas fell within the poor and very poor soils classes otherwise called marginal soils. CONCLUSION Generally, the soils in the area (South-eastern part of Adamawa State) are marginally suitable for cocoa production and will require special management techniques to obtain optimal productivity of cocoa. The physical and chemical characteristics of the sites indicated that the soils are critically deficient in nutrients required for cocoa production. Therefore, cocoa production can only be possible through the use of external inputs such as fertilizer application based on the results of soil test in addition to appropriate shade management and irrigation to complement the natural endowment in the area. REFERENCES. Akinwale, O., Prospects and challenges in local production of cocoa as raw materials in Nigeria Cocoa Mirror, : Smyth, A.J., 966. The Selection of Soils for Cocoa, Soils Bulletin No 5, Rome, FAO. 3. Opeke, L.K., Tropical Tree Crops Spectrum Books Ltd. Pub. Woye and sons Nigeria Ltd Ilorin, pp: International Institute of Tropical Agriculture, 982. nd IITA. Laboratory Manual 2 edition Klingebiel, A.A. and P.H. Montgomery, 96. Land-capability classification. Agric. Handbook 20. Soil conservation service, U.S Govt. Print office, Washington D.C. 6. Hardy, F., 960. Cacao Manual, Inter-American Inst. Agric. Sci: Turrialba, Costa Rica. 7. Egbe, N.E. and T.I. Omotoso, 97. Nutrition of cocoa in Nigeria, Annual Reports of Cocoa Research Institute of Nigeria (CRIN) Ibadan. 222

6 World J. Agric. Sci., 7 (2): , Hardy, F., 958. Cacao Soils Proc of Soil and crop. Smyth, A.J. and R.F. Montgomery, 962. The Soils Science Soc. of Florida, 8: and Land use of Central western Nigeria,Ibadan, 9. Wessel, M., 966. The soils of Gambari Experimental Western Nigeria, The Government Printers, pp: 265. station. CRIN Annual Report. 0. Wood, G.A.R., 989. Cocoa Environment. In Cocoa (Tropical Agricultural Series) co- published by Longman scientific and technical Eds., Wood, G.A.R and Lass, R.A, pp: