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Journal of Agriculture and Rural Research

ASSESSMENT OF SOIL FERTILITY STATUS IN SOME AREAS OF KOGI EAST AGROECOLOGICAL ZONE OF

Frank Ojochegbe Ojomah and *Paul Omaye Joseph

Department of Soil and Environmental Management, Faculty of Agriculture, Kogi State University, Anyigba, . *E-mail: [email protected], Telephone: +2348038275933 Received: 24th May, 2017 Accepted: 17th June 2017 Published: 17 th June, 2017

The objective of the study is to access soil fertility status in some selected areas of Kogi East agro-ecological zone. A total of nine (9) soil samples were randomly collected at a depth of 0-20 cm from each LGA in Kogi East. The samples were subjected to physicochemical analyses. The result showed that pH which ranged from 4.9 - 6.4 was within the critical level of 5.0 - 6.8 for crop production. However two locations, Shintaku (pH 4.9) and Ugwolawo (pH 4.6), which are strongly acid soils should be limed. The soils are low in salinity values of <250 µmho/cm. The content of exchangeable cations was moderate. The exchangeable acidity were very low as the sum of Al3+ and H+ were not up to 4 cmol/kg. The base saturations were very high above 80% which indicate the presence of basic nutrients. The result of trace element also revealed that they were normal and moderate. However, the soil in LGA with 53.01 ppm of Cu concentrations is very high which is toxic to plant and microorganisms. Soil of Kogi East agro-ecological zone offers great potentials for cassava and tree crops production due to its high base saturation.

Keywords: Agro-ecological zone, Cations, Crop production, pH, Soil fertility

INTRODUCTION

The soil is the collection of natural body arranged in layers (soil horizons) consisting of the mineral constituent; containing living matter and supporting or capable of supporting plant growth. Soils vary in their morphological, physical, chemical and mineralogical characteristics. Soil includes the horizons near the surface that differ from the underlying rock materials as a result of interactions through time, climate, living organism, parent materials and relief (Brandy and Weil, 1999). Soil fertility is the capacity of the soil to supply essential nutrients in adequate amount for the growth and development of the plant. Soil fertility determinations or evaluation forms the bases of making fertilizer recommendation (FAO, 2000). In Africa, soil fertility depletion and soil degradation present the most serious problems. According to an FAO (2000) study, the Africa soils lose an annual average of 48 kg/ha of nutrient, the equivalent of 100 kg/year of fertilizer. Soil fertility declines rapidly in cultivated lands through leaching, soil erosion and crop harvest (Mbah and Onweremadu, 2009). Tropical smallholder farming systems lack sustainability due to nutrient leaching, lack of fertility restoring inputs and unbalanced nutrient applications (Ajayi et al., 2007). About 86% of the countries in Sub-Saharan Africa lose more than 30 kg of nitrogen (N), phosphorus (P) and potassium (K) per hectare (ha-1) per annum (Henao and Baanante, 2006) and nutrient depletion can be particularly high in countries with high population densities such as Ethiopia (Johannes, 2000). Maintaining or increasing soil fertility is one of the most important things farmers have to do to increase output. Doing so, farmers have the characteristics and constraints of their soils and use sustainable agricultural practice and methods for conserving them and making them more fertile. These include fallowing, using compost manure, crop residues, and fertilizer tress; inter cropping legumes with cereals and including the principles of conservation agriculture. Soil fertility is largely maintained by the application of compost and manure but in recent years a decline in soil fertility has been reported. Intensification of crop production without appropriate soil fertility management commonly practiced by traditional farmers is not sustainable in the humid tropics as it leads to deterioration in physical, chemical and biological properties of the soil. The undesirable consequences are declining yield and low resource productivity which worsen poverty in rural agricultural communities (Suge et al., 2011). Eastern part of Kogi State is an agrarian area with a large percentage of populace engaged in farming and agricultural activities. Economic growth, food security and poverty alleviation of the state, therefore, depends on

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the development and the agricultural and agro-industrial sector, which is fundamentally affected by the productivity of land resources. However, agricultural production in this part of the state is hampered by the predominance of poor and declining soil fertility accelerated by degradation natural vegetation, lack of efficient soil- water management techniques, lack of adequate soil information, continuous cropping on the same plot of land etc. resulting in low agricultural productivity. In addition, a significant body of relevant indigenous knowledge has been documented (Lal and Stewart, 1995). Even though the decline in soil fertility is a major concern for most farmers, their adoption of improved techniques has been limited (Stevenson and Ardakani 1972). In the Eastern part of Kogi State, there is inadequate information on the fertility status and type of soil still today. Further Increase in the population has resulted in competition from land among various users without due consideration for the quality of the soil in the area to be able to ascertain whether they are fertile or infertile for agricultural use. For this, the study was undertaken to determine the fertility status of the soils in some selected areas of Kogi East agro-ecological zone.

MATERIALS AND METHODS

Study Sites Kogi East of Kogi State consists of nine (9) Local Government Areas namely; , Ofu, Omala, , , , Ibaji, Igalamela/odolu and Bassa. It covers a total land area of 30354.74 km2 (Federal Ministry of Land and Survey, 1997). It lies within lat. 70 30’N and long. 60 42’E (Amhakhian and Osemwota, 2010). The topography of the study areas is mainly undulating, plains or land slope. The major soil types are sand, loamy and clay soils. Crops grown in these areas include maize, cassava, soya bean, cowpea, rice, yam, cashew, mango, oil palm, sugarcane etc. Climate The location of sites lies within the warm humid climate of the middle belt zone of Nigeria with a clear distinctive wet and dry seasons. Kogi East agro-ecological zone has a bimodal rainfall with peak pattern occurring in July and September. The mean annual rainfall is 1,808 mm (Amhakhian et al., 2012). The temperature shows some variation throughout the year. Average monthly temperature varies from 17oC to 36.2oC. Relative humidity is moderately high and varies from an average of 65 - 85% throughout the year (Amhakhian et al., 2012). Vegetation and Land Use The vegetation consists of rain forest on the eastern and typical wood land savanna and grassland to the western part. This vegetation is as a result of heavy rainfall incidence which is usually prolonged. The persistence felling of tress for timber associated with the filling of the soil for arable agriculture, bush fallowing and bush burning lead to the development of re-growth vegetation at a high rate. Economic trees associated with this vegetation includes Mahogany, locust bean tree, African iron, shear butter, mango, cashew, palm tree, gmelina, coconut, shrubs etc. The food crops grown are cassava, maize, rice, yam, soya bean and legumes crop. Table 1: Land use and soil classification of sampling and experimental soils Sampling locations Coordinates Land use Anyigba 70 30’N/70 09’E Oil palm, cassava, mango, maize, yam and cashew. Abejukolo 70 40’N/70 16’E Cassava, pigeon pea, orange and groundnut. Ajaka 70 09’N/60 49’E Bambara nut, tomato and yam Ochadamu 70 19’N/70 00’E Cashew, orange, cassava and oil palm Idah 70 06’N/60 43’E Pepper, cassava, yam and rice Imane 70 12’N/70 31’E Cassava, oil palm and yam Ibaji 60 40’N/60 48’E Rice, yam, sugarcane, oil palm and cassava Ikanekpo 70 22’N/70 36’E Oil palm, yam and cassava Odenyi 70 47’N/70 02’E Sugarcane, cassava and mango Source- 1: Kogi State Agriculture Development Project Zonal Office Anyigba. Soil Sampling Soil samples were taken from nine (9) Local Government Areas mentioned above at a depth of 0-20 cm. Composite sample was taken in an area in each Local Government Area per sampling depth. The samples collected were air-dried, crushed, grind and passed through a 2 mm sieve and material larger than 2 mm diameter were removed. Composite sample from each location was labeled and stored in polythene bag for laboratory analysis.

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Soil Analysis: A representative of each sample collected was analyzed for pH, electrical, conductivity, particle size distribution, cation exchange capacity, organic matter available phosphorus, total nitrogen, trace elements, exchangeable bases, exchangeable acidity and percentage base saturation. Particle size analysis: A fifty grams (50 g) sample of the soil was weighed into a beaker and 50 ml of Calgon (35.7 g) sodium hexametaphosphate and 7.94 g sodium carbonate into 1 litre of distilled water) was added into the beaker. Ten millilitres (10 ml) of de-ionized water was added into a beaker, stirred and allowed to stand for 30 minutes. It was then transferred into a measuring cylinder and de-ionized water was added to make up to a litre volume. The temperature was measured as T1, the sample was mixed with a plunger ten (10) times and the hydrometer was dropped immediately into the suspension. The reading of the hydrometer was taken after 40 seconds as H1 and after two hours as H2. At this point, the temperature reading was taken again as T2. The percentage sand, silt and clay were determined according to Gee and Bauder (1985). The textural classes of the soils were determined using the textural triangle (Bouyoucos, 1951). Physico-Chemical Analysis of Soil The total nitrogen (N) was determined using the Kjeldahl digestion method (Bremner and Mulvaney, 1982). Available phosphorus (P) was determined using Bray and Kurtz (1945) extraction procedure. Organic carbon was determined using the Walkley-Black wet oxidation method (Walkley and Black, 1934). The exchangeable bases

(Ca, Mg, K, Na) were extracted with 1 N NH4OAc buffered at pH 7.0 (Thomas, 1982). The Ca and Mg were determined using atomic absorption spectrophotometer. K and Na were determined using the flame photometer. Exchangeable acidity extracted with Kcl (Thomas, 1982) and determined by titration with 0.05 N NaOH using phenolphthalein as indicator. The pH of the soil was determined using pH meter (Maclean, 1982). The electrical conductivity was determined using the EC electron (Chen, 1998). The percentage base saturation was calculated by multiplying the quotient of TEB to ECEC by 100. The trace elements were determined using atomic absorption spectrophotometer. Results and Discussion Soil Reaction Soil pH ranged from 4.9 to 6.4 with a mean value of 5.8 in water and potassium chloride pH range from 4.4 to 5.8 with a mean value of 5.3. This range of pH value favours nutrient availability to crop plant since pH of most agricultural soil in Nigeria has been reported to range from 4.00 - 6.5 (Hartly, 1988). The studied areas had pH range favourable for the growth of crops such as potato (4.5 – 6.0), groundnut and wheat (5.5 – 6.5), maize (6.0 - 7.0), Soybean (6.5 -7.0), rice and cowpea (5.0 – 6.8) (Chude et al., 2005); Ibaji soil had the highest pH of 6.3 and 5.8 in water and KCl, respectively, while Bassa had the lowest pH of 4.9 and 4.4 in water and KCl, respectively. However, locations such as Shintaku (pH 4.9), Ugwulawo (pH 4.6) which are strong acid soils, according to Chude et al. (2005), should be limed to increase the pH. Farmers in these areas should apply organic matter rather than acid forming fertilizers such as sulphur and phosphorus fertilizers because the soils of these areas are already acidic. Soil Electrical Conductivity Table 2 showed that the EC range of 70 - 220 µmho/cm at 0 - 20 cm depth falls within the range of low salinity and also the mean range of 130 µmho/cm falls within the range of low salinity which agrees with USDA – SCS (1974). Bassa soil had the highest EC of 220 µmho/cm, while Dekina had the lowest (70 µmho/cm). Therefore, crops tolerant to salinity rather than sensitive ones should be grown in these areas. High EC which entails salinity problem affects the water holding capacity of soils, plant and microbial activities of the soil as observed by (Nelson and Sommers, 1982). Particle Size Distribution The knowledge of proportions of different sized particles in a soil is critical for understanding soil behavior and management. Silt particle ranged from 1.25 % to 41.28 % while the mean value of 9.94 %. Clay soil ranged from 7.38 % to 29.76 % with a mean value of 14.81 %. While the sand fraction ranged from 28.96 % to 89.34 % with a mean value of 75.24 %. Location within the studied area such as Ofu and Olamaboro LGA with the textural class of sand will affect the productivity of the soil. This is because Sandy soils have low water holding capacity, low nutrient and organic matter content as reported by Brandy and Weil (2004). Sandy soils account fo r poor structural stability and aggregation. They are easily leached and washed by water erosion. This water erosion has implication on soil fertility status and quality because it removes nutrient-rich topsoil, reduce the level of organic matter and contribute to breakdown of soil structure as reported by Anon (2006); also sediment can damage fish habitat and degrade water quality, blowing dust by the wind can affect human health and create public safety hazard leading to less favorable environment for plant growth.

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Table 2: The physico-chemical properties of soils in Kogi East Agro-ecological zone

LGA Village pH pH EC(µmho % % % Sand Textural class Available water KCl s /cm) Silt Clay phosphorus (Mg / Kg or Ppm) Ankpa Ankpa 6.2 5.6 170 3.28 10.48 86.24 Loamy sand 6.82 town Bassa Shintaku 4.9 4.4 220 21.28 28.48 50.24 Sandy clay 4.82 loam Dekina Anyangba 6.0 5.5 70 1.28 13.27 85.45 Loamy sand 11.91 Idah Idah Town 5.7 5.1 90 9.25 12.48 78.24 Loamy sand 7.12 Igalamela Ajaka 5.9 5.4 100 1.25 12.48 86.24 Loamy sand 9.64 Ofu Ugwulawo 5.2 4.6 80 3.28 8.48 88.24 Sand 6.48 Olamaboro Imane 5.8 5.2 90 3.28 7.38 89.34 Sand 6.77 Omala Abejukolo 6.4 5.7 190 5.28 10.48 84.24 Loamy sand 14.79 Ibaji Ejule 6.3 5.8 160 41.28 29.76 28.96 Clay loam 7.21 Ojiebe Mean 5.8 5.3 130 9.94 14.81 75.24 8.40 Standard error 0.16 0.15 17.36 2.40 2.59 6.64 0.99

Available Phosphorus Available P ranged from 4.82 to 14.79 mg/kg with a mean value of 8.40 mg/kg in the soil. This range of value is below the critical value of 15 mg/kg (Enwezor et al., 1981) for crop production. When P deficiency occurs, it is usually due to a severe inadequacy of P in the soil solution or in some cases it may be due to a restricted root system as a result of cool – moist growing conditions. Omala soil has the highest available P of 14.79 ppm, while ofu has the lowest (6.48). Organic Matter The soil organic matter varies from 0.55 – 1.84 % with a mean value of 0.90 % in the soil. This range of value is rated very low in surface soils which reflect the amount of organic matter in soil considering the fact that the soils are below the critical level of organic matter (3.4 %) (Anon, 1990). In fact, most samples ranged between 0.8 % and 1.5 %. Ideally, an agricultural soil should have an organic matter level greater than 2 %. These come about by intensifying cropping patterns, reducing the amount of tillage and fallow, incorporating green manures and using diversified crop rotations. However, a location such as Ibaji (1.84 %) and Omala (1.17 %) has the highest percentage of organic matter. This may be as a result of high clay and silt proportion or colloidal nature, while Idah has the lowest (0.55%) Total Nitrogen Total nitrogen content ranged from 0.02 – 0.05 % with mean value of 0.03 %. These values are rated low in surface soil (Sobulo and Osiname, 1981), which reflected the amount of organic matter in soil considering the fact that these soil is below the critical level of Nitrogen (0.15 %) for optimum crop production. It has been observed that the main cause of N deficiency in tropical soils is intense leaching and erosion due to high tropical rainfall (Sobulo and Osiname, 1981). Exchangeable Cations Exchangeable Calcium range from 2.62 to 4.71 % with a mean of 3.49 % which indicate high calcium, magnesium is also high (1.74 - 2.22 %) with a mean value of 1.96 %. It indicates that Ca and Mg was above the critical level of 2.0 – 0.4 % (Anon, 1990). Calcium deficiencies are not unusual, although the crops where calcium is particularly important are the fruit crops, such as apples, peaches, and tomato. Calcium deficiency will significantly affect fruit quality (Thomas,

1982). Mg deficiencies can be induced by excessive K and NH4. N Fertilization when the soil pH is less than 5.4, Mg availability and uptake by plants is generally reduced. Potassium is high (>2 %) with a mean value of 2.30 %. Potassium balance in the plant is important. The K/(Ca + Mg) and K/N balances must be maintained at a proper level to avoid deficiencies of Mg in the First instance and K in the second. Sodium is moderate (>0.84 %) with a mean value of 1.12 %. Exchangeable Acidity The result of the exchangeable acidity (Aluminum and hydrogen) ranged from 0.67 – 1.05 cmol/kg with a mean value of 0.92 cmol/kg. This implies that exchangeable acidity value was <4 cmol/kg in the soil. This value reflects the moderate acidity or neutral pH values for some soil (FAO, 2000).

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Table 3: The chemical properties of soils in Kogi East Agro-ecological zone

Exchangeable Cations (cmol/kg) Trace Element (ppm)

LGA Village % OM % Ca K Mg Na ExB ExA CEC PBS Zn Cu Fe S N Ankpa Ankpa town 0.87 0.03 3.69 2.49 2.22 1.31 9.71 0.88 10.59 91.69 0.75 1.81 1.42 0.02

Bassa Shintaku 0.69 0.02 3.02 2.72 2.02 1.20 8.96 1.05 10.01 89.51 0.21 1.74 1.74 0.05

Dekina Anyigba 0.84 0.02 4.71 2.56 1.74 1.04 10.05 0.91 10.96 91.70 1.62 1.57 1.20 0.01

Idah Idah 0.55 0.02 3.52 2.16 1.81 1.28 8.77 0.99 9.76 89.86 0.18 1.30 1.23 0.07 Town Igalamela Ajaka 0.81 0.02 2.87 2.49 2.11 1.17 8.64 0.98 9.62 89.81 1.10 1.63 1.48 0.03

Ofu Ugwulawo 0.66 0.02 2.62 2.10 1.80 0.84 7.36 1.01 8.37 87.93 0.20 2.74 1.26 0.01

Olamaboro Imane 0.67 0.02 4.42 2.06 2.12 1.08 9.68 0.95 10.63 91.06 0.15 1.78 1.19 0.03

Omala Abejukolo 1.17 0.03 2.77 2.51 1.93 1.18 8.39 0.83 9.22 90.99 3.91 1.41 1.24 0.08

Ibaji Ejule 1.84 0.05 3.75 1.58 1.92 1.00 8.25 0.67 8.92 92.49 0.58 53.01 16.52 0.12 Ojiebe Mean 0.90 0.03 3.49 2.30 1.96 1.12 8.87 0.92 9.79 90.56 0.97 7.44 3.03 0.04

Standard error 0.12 0.00 0.23 0.11 0.05 0.05 0.27 0.04 0.27 0.44 0.38 5.38 1.59 0.02

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Cation Exchange Capacity The result obtained revealed low CEC with ranges of 8.37 – 10.96 cmol/kg with a mean value of 9.79 cmol/kg. This suggests that the CEC of a soil is permanent characteristic and is directly related to the soil texture. The higher the clay content of any soil, the higher the CEC of the soil. In general, the CEC of most soils increases with an increase in soil pH (FAO, 2000). Percentage base Saturation (PBS) This ranged from 87.93 – 92.49 cmol/kg with mean value of 90.56 cmol/kg in the soil. This indicate the presence of basic nutrient in available form in the soil solution for plant uptake (<80 cmol/kg) Zinc (Zn) The Zn content in the soils ranged from 0.15 – 3.91 ppm with a mean value of 0.97 ppm. This value falls below the normal range of Zn in the most plant which is between 20 to 100 pmm (Anon, 1990). It means the soil is deficient in Zn concentration. Zn deficiencies occur in a wide variety of plant when the leaf level drops below 15 ppm. In order to avoid Zn deficiency, Zn level in most plant crops should be maintained at 20 ppm or better. Zinc toxicity is an uncommon problem and does not generally occur until the Zn level exceeds 200 ppm (Anon, 1990). Copper (Cu) The Cu content in the soils ranged from 1.30 – 53.01 ppm with a mean value of 7.44 ppm. The mean value of 7.44 ppm is normal and moderate to the normal range of Cu in many plants which range from 5 to 20 ppm (Jones et al., 1991). When the Cu concentration in plants is less than 3 ppm in the dry matter, deficiencies are likely to occur. When Cu levels exceed 20 ppm in the plant, toxicities may occur. However, the soil in Ibaji LGA with 53.01 ppm concentration of Cu which will be toxic to plant and microorganisms and also antagonism between Cu and Zn has been observed (Isirimah et al., 2003). There are some variations in the critical values for various plant species; However, most critical values have been determined to be somewhere between 3 to 10 ppm for most crops. Iron (Fe) The Fe content in the soils ranged from 1.19 - 16.52 ppm with a mean value of 3.03 pmm. The ranges of value fall below the critical level of 50 ppm (Isirimah et al., 2003). The Fe content in the plant can vary considerably. In general, when the Fe concentration in soil is 50 ppm or less, deficiency is likely to occur (Isirimah et al. 2003). The grasses and corn have a lower Fe requirement the critical level being 20 ppm. Iron toxicity has not been reported for any field crops growing under natural conditions. Iron deficiency is very difficult to correct in some crops. The application of some forms of Fe to the soil is not practical. Foliar applications of Fe have been found to be effective in correcting Fe deficiencies in plant. Sulphur The sulphur content in the soils ranged from 0.01 – 0.08 ppm with mean value of 0.04 ppm which indicates that sulphur is below the critical level of 0.10 % requirement for most crops (Anon, 1990).

CONCLUSION

From this study, it can be concluded that most soils within the studied areas have favorable pH range for arable crop production; very low level of salinity where by tolerant crops can yield satisfactorily, most of the soils in the studied areas falls in the loamy sand textural class. However, locations such as Ofu LGA (Ugwulawo), Olamaboro LGA (Imane) with sand textural class have to change their cropping pattern. The cation exchange capacity was moderate in value and the percentage base saturation recorded high values from the samples analyzed. Sustainable crop production of these soils will require the maintenance of productivity potentials of the soil by moderate application of inorganic phosphorus and organic manure which will boost the yield of most crops grown on the soils. Therefore, the availability of this baseline information of the studied areas will provide farmers opportunity to be aware of their soil fertility status and appropriate conservation, maintenance, improvement and productive management of these soils.

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