Nigerian Journal of Soil and Environmental Research

Characterization and classification of soils along a typical Hillslope in Afikpo area of Ebonyi state, Nigeria

I.E Esu, A.U Akpan-Idiok, M.O Eyong

Three pedons representing soils on the summit to shoulder (Pedon 1), backslope to footslope (Pedon 2) and toeslope (Pedon 3) positions along a typical hillslope in Afikpo area of Ebonyi State of Nigeria were studied regarding their morphological, physico-chemical and mineralogical properties. The soils were also classified according to the criteria of the USDA Soil Taxonomy and the FAO World Reference Base for Soil Resources. Soils of Pedons 1 & 2 occur on very strongly sloping, severely eroded uplands and are derived from ferruginous, feldspathic sandstone with shale intercalations. The soils in the toeslope position, occur on extensive, nearly level plains which are seasonally waterlogged with colluvio-alluvial sediments constituting the parent material. Irrespective of slope position, all the soils are very strongly acidic with a narrow pH range of 4.6 – 5. 1 and an average exch. Al3+ content of 3.77cmol kg-1 in all the horizons studied. Levels of organic C, total N, avail. P, exch. Ca, Mg, and K, range from being very low in Pedon 1, low to moderate in Pedon 2 but moderate to high in Pedon 3 indicating a gradual improvement in soil fertility from the summit to the toeslope of the hillslope . Kaolinite, mica, quartz, microcline, plagioclase, goethite and gibbsite were detected in the silt fraction of all the soils while kaolinite and poorly ordered illite as well as Fe-rich chlorite dominated the clay mineralogy. According to the criteria of the USDA Soil Taxonomy, the upland soils are Typic Udorthents while the valley bottom soils are Mollic Fluvaquents. In the FAO-WRB system, they qualify as Hper-Dystric Regosols and Mollic Gleysols respectively. Recommendations regarding soil management options have been included.

Key words: acid soils, characterization, classification, Entisols, hillslope

ClasSoil Genesis in Volcanic Areas of the Jos Plateau, Nigeria.sification of soils planted with orange (citrus sinensis) and mango (mangifera indica) in the Nigerian guinea savanna

E.A Olowolafe

The purpose of this study was to explain the genesis of soils formed in the volcanic areas of the Jos Plateau, Nigeria. Ten soil profile pits, representing the various landscape segments of a typical volcano and a lava plain, were dug, described and sampled for physical, chemical and mineralogical analyses. The results show early, moderate and advanced stages of soil development on the cones, upper / middle footslopes and toeslopes, respectively, indicating that soil maturity stage increases from the crest down to the toeslopes. Amorphous clay minerals are found in the young soils while kaolinite dominates the clay fraction in the mature ones. Similarly, soil pH, organic carbon, exchangeable bases and CEC decrease as soil maturity increases. The important soil forming processes in the study area include addition of organic matter, clay formation from hydrolytic weathering, soil structure formation, clay migration (eluviation and illuviation), acidification, loss of basic cations through leaching, gleying, ferralization and allitization. The major weathering process is that of hydrolytic weathering of the pyroclastic materials, including basaltic rocks, pumice, lava and ash. Soil erosion and aeolian sedimentation have affected the soils. Intensive weathering and leaching precluded the formation of 2:1 clay minerals. In the same vein, because of the effects of tropical climate the soils could not meet the requirements of Andisols.

Key words: Soil genesis, Soil properties, Volcanic areas, Jos Plateau, Nigeria.

Profile distribution of total and available Sulphur and boron in sandy soils of Nigerian semi-arid savanna .

B.A Raji

The total and available sulphur and boron forms were determined in sandy soils formed from sand dunes, sandy alluvial terrace and sandstone formation in northwestern Nigeria. Hot water and Morgan’s solution (sodium acetate/acetic acid solution buffered at pH 4.8) were used as extractants for available boron while calcium phosphate solution was the extractant for available sulphur. In the surface horizons, in all the sandy soils, total boron ranged from 2.03 to 170.85 mg kg-1 soil, while subsoil values varied from 0.59 to 135 mg kg-1 soil. The means of the total boron are highly significantly (p=0.001) different among the sandy soils. The means of hot water extractable boron (Bhw) are also significantly (p=0.05) different for the sandy soils. Generally boron values are significantly higher in the surface horizons than in the sub-surface horizons. In terms of magnitude, the sandy soils may be arranged as follows: Rabah terrace > Wurno sandstone > Sangiwa dunes > Illela dunes > Sokoto dunes. The mean values of calcium phosphate extractable sulphur are significantly (p=0.05) different among the sandy soils. Values in the surface horizons are also generally higher than the sub-surface horizons. The values of Sc are higher in the sand dune soils than the sandstone and terrace soils within the study area. By the critical limits of 0.1 to 0.2 mg kg-1 given in the literature for Nigerian savanna soils, the sandy soils understudied appear to be slightly above this limit especially for the terrace and sandstone soils. For the sand dune soils the surface horizons are marginally adequate but the subsoils are below the critical limit. If the
critical limit of 4 mg kg-1 quoted in the literature is considered, all the sandy soils understudied are deficient in available sulphur except for soils derived from Illela sand dune, which are only marginally sufficient. For optimum crop production on sandy soils within the study area, sulphur and boron addition through the use of boronated single supper phosphate and other sulphur-based fertilizers should therefore, be encouraged.

Nitrogen fertilizer replacement value of legumes with residues incorporated in the guinea savanna zone of Nigeria

M.K.A Adeboye

Crop rotation with legumes can help reduce the inorganic nitrogen fertilizer need of the following maize as a result of increased nitrogen availability in the soil. The Nitrogen Fertilizer Replacement Value (NFRV) method was used to estimate the nitrogen contribution of grain legumes (soybean, cowpea) and an herbaceous legume (Centrosema pascuorum), to a succeeding maize crop. The legumes and fallow fields were established in 2001 followed by a test crop of maize in 2002 with inorganic fertilizer rate of 0, 20, 40 and 60 kg N ha-1. The soil inorganic nitrogen was significantly (P< 0.05) increased by 100 and 150 % by soybean and Centrosema residue incorporation respectively while fallow residue incorporation did not change the level. Maize grain yields were significantly (P< 0.05) higher after the legumes than that after fallow. Succeeding maize crops had lower response after soybean than after Centrosema while the fallow had a high response to inorganic nitrogen fertilization. Soybean had the greatest NFRV of 55 kg N ha-1 followed by Centrosema, 34 kg N ha-1 and cowpea, 10 kg N ha-1. The effects of the legumes on the grain yield and nitrogen needs of the succeeding maize were considered to be due to the improved soil nitrogen status after the legumes. Integration of legumes into the cropping systems of the zone is highly recommended to enhance crop productivity.

Key words: Guinea savanna, incorporation, legume residues, N fertilizer replacement value.

Fertility status and management of a tropudult toposequence sustaining gmelina arborea roxb plantation in humid forest zone of southeastern Nigeria.

A.N Essoka, E.E Oku, E.A Otonko, P.A Essoka

This Gmelina arborea plantation was established on Tropudults since 1976 to supply raw material to a Newsprint Manufacturing company in Nigeria. The main objective of this study was to investigate the native fertility status and recommend management strategies of this Tropudults sustaining the plantation. Profile pits were dung at the crest, middle slope and valley bottom. Core samples were collected for physicochemical analysis. All the profiles had coarse texture. Bulk density ranged between 0.75 - 1.25g cm-3 that do not hinder root penetration. Porosity ranged from 53 – 73 % hence best for agricultural soils, while pH was acidic ranging from 4.51 – 4.80. Organic matter value of 2.84 % and 2.24 % for surface horizon of middle slope and valley bottom respectively were considered medium whereas that of the crest was considered low (1.12 %). The major nutrients; nitrogen, phosphorus and potassium (NPK) were rated below critical levels (N < 0.1 %, P < 10 mg kg –1 and K < 0.15 cmol kg-1). The sulphur content was rated medium (between 5.0 – 7.0 mg kg-1). The contents of exchangeable Ca, Mg and Na were below critical levels (Ca < 2.5 cmol kg-1., Mg < 0.3 cmol kg-1 and Na < 0.35 cmol kg-1). The base saturation calculated was appreciable (49%). the effective cation exchange capacity (ECEC), the electrical conductivity (EC) and exchangeable acidity (EA) were all low. These chemical properties results indicate that the soil sustaining this plantation is poor in native fertility. Application of lime, inorganic fertilizer and/or avoidance of annual bush fire are a necessity, if soil fertility and land use sustainability must be maximized.

Keywords: Gmelina arborea, Tropudults, fertility status, humid tropics, Nigeria.

Properties and suggested management strategies for some well drained maize producing soils of north-western Nigeria

T Kparmwang

Some well drained maize growing soils of the northwest Agricultural Zone of Nigeria were characterized, classified and management strategies proffered for them. The soils were moderately deep to deep (65 - 150 cm), well drained and well structured, yellowish brown (10YR 5/4, 5/8) to yellowish red (5YR 4/6, 4/8) loams. Soil reaction ranged from very strongly acid to neutral (pH 5.0 - 6.8). Exchangeable Ca (< 2 cmol kg-1) and K (< 0.15 cmol kg-1), organic carbon (< 10 g kg-1), total N (< 1.5 g kg-1), P (< 10 mg kg-1) and Cu (< 1mg kg-1) were low, while exchangeable Mg (0.3-1.0 cmol+ kg-1), CEC (6-12 cmol+ kg-1) and available Zn (> 1 mg kg-1) were medium. The CEC values of the soils show that they are not suitable for continuous cultivation but would require a high ratio of fallow or grass-legume pasture to crops. This option should, therefore, be followed in their management. Should they be used for continuous cultivation, soil OM levels must be raised to ≥ 20 g kg-1 (≥ 15 g kg-1) soil, by applying FYM and animal dung. This strategy would raise CEC, buffering capacity and base saturation and improve soil structure and water and nutrient retention capabilities.

Land Evaluation for Sustainable Urban Land Use in the Humid Forest Agroecological Zone of Southwestern Nigeria

G.E Akinbol, T.O Umeokafor, J.C Obi

Urban sprawl represents one of the major soil-related threats in any given environment. It is ecologically and aesthetically desirable to use land efficiently for sustainable urban development. The process of urban development inevitably affects the ecological balance of any environment. Land evaluation for such development will help to resolve the problems of efficient allocation of lands for the purpose they are best suited. Thus, this study assessed the suitability of an 89 ha of land for urban land use and development, in a forested ecosystem of southwestern Nigeria. This involved semi-detailed soil survey and land evaluation. About 37% of the total area studied belong to Urban Land Use Capability (ULUC) class Ao, possessing negligible physical constraints to urban development and sustained urban use. Fifty-five percent of the land has slight erosion problems by particle movement, therefore belonging to ULUC class Bo, while about 8% (classified as ULUC class Cdw) has high water table with poor drainage and flooding as major physical constraint for development. These are indications that ULUC studies should form part of the basic information for engineering designs and construction, land owners’ and policy makers’ decision making process to enhance environmental stability and sustainability.

Keywords: urban land use; sustainable development; land evaluation, land capability classification

Seasonal streamflow estimation in a woodlot subcatchment

D.O Onwuegbunam, M.A Oyebode, O.J Mudiare

In the present study, an attempt was made to evaluate the total seasonal stream flow, in terms of both surface runoff and baseflow contributions in a 25.5 ha woodlot subcatchment of New-Afaka, Kaduna in the Northern Guinea Savanna ecological zone of Nigeria. The seasonal flow could be impounded and harnessed for dry season irrigation of crops in 20.3 to 79.2 ha out of about 125 ha of arable land which exists downstream the drainage basin. The total seasonal flow, measured as change in volumetric storage of an earthdam at the watershed outlet, and by means of a weir installed in an outflow channel that drained the dam spillage was 435,606m3. The direct runoff and base flow contribution was in the ratio of 1:24, the seasonal flow being described as a groundwater-sustained ephemeral stream.

Key Words: seasonal flow, runoff, baseflow, catchment, irrigation, drainage

The impact of cement kiln dust on soil Physico-chemical properties at Gboko, east central Nigeria

C.L Asadu, C Agada

The effects of cement kiln dust on selected soil physico-chemical properties after 25 years of cement production by the Benue cement factory in Gboko, Nigeria were evaluated by comparing the cement-dust affected soils with non-affected soils. The study showed that at both soil depths of 0-20 and 20-40 cm exchangeable calcium, sodium, hydrogen, magnesium as well as soil organic matter, were significantly higher in the affected soils than in the non-affected soils, the former depth at P≤ 0.05 and the latter at P≤ 0.01. Data from the four representative soil profiles also indicated that some of the soil properties were enhanced by the cement dust. The study also showed that the highest quantity of the cement dust obtained in the farm plot was 0.72t/ha/yr, a quantity too negligible to cause any negative effects on soils and crops. Thus, presently the cement dust from the factory enhanced the majority of the selected properties of the soils and may manifest positively on crop performance around the area in future hence if properly harnessed may contribute to soil fertility management in the affected soil areas.

Evaluating the Acid Soils for Aquaculture in Fish Pond Development in Akwa Ibom State, Southeastern Nigeria

P.I Ogban, G.S Effiong, T.O Ibia

Declining natural fish stocks due to over-exploitation of finite water resources and loss of habitats resulting from discharge of toxic contaminants, and increasing demand for fish products due to increasing population have necessitated the expansion of aquacultural development from aquatic ecosystems to upland ecosystems. Studies were conducted at seven representative locations to evaluate the suitability of the acid soils for aquaculture in pond development in Akwa Ibom State, Southeastern Nigeria. Morphologically, a hue of 7.5 YR typifies the upland soils. The soils have a weak, medium sub-augular blocky structure, and consistence varying from very friable in the topsoil to friable at lower profile depth. The predominant particle-size fraction is sand averaging between 73.9 and 85%, while the clay fraction ranges from 10.7 to 23.1%, and soil texture varies from sand to sandy clay loam. Average values of soil density varies from low (1.14 g/cm3) to high (1.66 g/cm3). Hydraulic conductivity (Ks) ranges from slow (1.01 cm/h) to rapid (8.31 cm/h). Infiltration rate at the soil surface and at 60 cm depth ranges from 4.80 to 84.8 cm/h and 0.78 to 2.16 cm/h respectively. Maximum available water capacity is low ranging from 5.57 to 11.92 cm. The soils are slightly acidic with pH ranging from 5.2 to 6.1. Electrical conductivity range from 0.01 to 0.057 dS/m. Organic C content varies from low (0.79%) to medium (1.29%). Available P ranges from low (7.12 mg/kg) to high (112.21 mg/kg). Effective CEC is generally low, mean profile values range from 5.25 to 7.92 cmol/kg. Base saturation is moderately low, averaging between 33.9 and 54.2%. The results show that the soils of the upland ecosystems are naturally unsuitable for earthen fish pond development. Remedial measures to alleviate the physical and chemical constraints to aquaculture in fish pond development have been discussed.

Keywords: Upland ecosystems, acid soils, soil characteristics, earthen fish pond development.