The project is considering road dualization along Uyo-Etinan axis. The location is within the Niger Delta ecosystem in Akwa Ibom State cover between Latitudes 4˚59'N and 4˚50'N and Longitudes 7˚49'E and 7˚5'E. The relief is gently undulating with the general sloping of the land towards the adjacent side at Ikot Oku Ikono section of the road. The soils are derived from coastal plains and are poorly drained due to underground plastic clayey layers with galloping terrain in some locations. The fieldwork plan consisted of soil sampling pattern and sample distribution. The major considerations for these included: 1) baseline data gathering of the specific soil environment of the proposed project; 2) proposed project activities/construction and their spatial locations and; 3) potential project activities/soil environment interfaces (representing potential project impact(s) on the soil environment). A sampling plan involving a combination of judgment (based on the above considerations) and systematic samples were adopted. Ten sampling stations were distributed, in a stratified random manner, to cover the proposed site for the road dualization project.

In addition, considerations were given to all the observed soil morphological types. The sampling stations were coded SS1, SS2, SS3, SS4, SS5, SS6, SS7, SS8, SS9, and SS10. Furthermore, another set of core samples were collected for determination of bulk density, porosity, and saturated hydraulic conductivity (Ksat). Soil samples were collected from randomly selected geo-referenced and spatially distributed spots in the study area along the transect lines at two depths (Surface: 0 to 15 cm and sub-surface: 15 to 30 cm) in each sampling point using a Dutch auger (Figure 1) and core samplers. Samples were stored in labelled polyethylene bags for physical and chemical analysis. The samples were qualitatively transported to the laboratory for further processes. All samples were chained custody in the field to facilitate tracking of the samples from the field and the laboratory. On the whole, forty (40) soil samples were collected and transported to the laboratory for analysis.

Analysis was carried out on soil samples for particle size distribution, bulk density, porosity, and Ksat, pH (soil reaction), electrical conductivity, organic C contents, total nitrogen, available phosphorus and exchangeable cations (K, Ca, Mg and Na), effective cation exchange capacity and percent base saturation.

The particle size distribution is a fundamental index of soil physical properties. Knowledge of this property allows prediction of many other soil properties [10] . In general, the soils of the humid tropics are subject to intense rain storms which often cause clay eluviations with resultant tendency toward coarse texture in the surface horizons. The physico-chemistry of soil samples from field (Table 1 and Table 2) showed that the soils are dominated by sand and loamy sand. The mean values for the particle size distribution of surface soils (0 - 15 cm) are 88.48%, 10.98% and 4.70% for sand, silt and clay, respectively. Sub soil (15 - 30 cm) results indicated that mean percent sand, silt and clay are 89.91%, 2.31% and 7.78% respectively. Normally, soil fertility increases with clay content because of the large surface area. Thus the production capacity of these soils is low.

The bulk density varied from 1.13 g∙cm⁻³ (SS8) to 1.42 g∙cm⁻³ (SS10) on the surface soils and from 0.95 g∙cm⁻³ (SS2) to 1.33 g∙cm⁻³ (SS8). The activity on the road side has not influenced the bulk density negatively as would have expected.

Where S = sandy, LS = loamy sand, CV = coefficient of variation.

The soil volume consisted of pore space, and the pore space would be half-filled with water and half-filled with air [9] . Actually the total porosity varies slightly with soils at different sampling stations. The locations mostly affected were stations; SS1, SS2, SS4 and SS10, where the average porosity was between 14% and 26% higher than optimum.

This implies that runoff and erosion losses of soil and nutrients are occasioned by excessive and tortuous pore spaces when surface water is restricted from moving through the soil. Plant, tree and forest ecosystem are particularly sensitive to increases in porosity. The anthropogenic activity of the area generally disturbed configuration of the pore spaces especially in the subsurface soil. This level of pore distortion at these locations may result in yield reductions, deplete respiration by plant root especially under wet condition and alter many soil reactions, in turn many soil properties.

Furthermore, the readiness of the soil to allow fluid to pass through it accounts for its permeability [11] . Figure 2 showed the saturated hydraulic conductivity (Ksat) distribution of soils at different locations along Uyo-Etinan Road. The Ksat rate of this area is most responsive to conditions near the soil surface and changes drastically with depth. According to Sarrantonio et al. [12] , Ksat is rapid into large continuous pores at the soil surface and decreases as the size of these pores is reduced. Hillel [13] reported that the coarser size fractions acted as an energy source for saturated hydraulic conductivity Ksat. The trend of accumulative saturated hydraulic conductivity of soils is continous higher on the surface soil compared to the subsurface. The soils at locations 3, 4, and 5 exhibited the highest non-equal uniformity permeability and the least impermeable

permeability classes. Edem et al. [14] found that a continous flux of Ksat on the surface soil without a corresponding flow in the subsurface during rainstorm will lead to immediate over-land flow in less than 30 minutes of storm due to proportion of silt to clay ratio.

Soil reaction which is given in terms of pH value is a measure of the free hydrogen ion (H⁺) concentration of soil solution. The value of the free H⁺ concentration in a soil influences the availability of nutrient elements and biochemical reactions in the soil [15] . In strongly acidic soils for instance basic cation uptake by plant roots is inhibited [16] . Beneficial soil micro organisms are affected by soil reaction [17] . The pH of the soil of the Uyo-Etinan dualization road (Table 3 and Table 4) ranged from strongly acidic to slightly acidic. It ranged from a very strong acidic value of 4.7 (sample stations 8) to strongly acidic value of 5.3 (sample station 2) at the surface level and from 4.2 (sample station 8) to 5.7 (sample station 3) at the sub surface level. Soil pH is often considered in terms of the soil capability and suitability to support plant growth. The pH of 4.8 is set as the lower limit for optimum growth of plants, and conversely the pH of 9.5 is regarded as the extreme upper limit of alkalinity at which plants can still grow [18] . Even though the soil pH value of sample stations 7 and 8 (subsoil) is short of this limit, the coefficient of variation among sampling stations is low, thus the soil pH of Uyo-Etinan dualization road can support plant growth.

The electrical conductivity of a soil indicates the total ionic strength (anions and cations) of such a soil. Low total ionic strength in a soil indicates low dissolved

salt contents and vice versa. Consequently Electrical conductivity increases with higher amount of soluble salts. Electrical conductivity values of soils of Uyo-Etinan dualization road ranged from 0.026 dS∙m⁻¹ (sample station 6) to 0.087 dS∙m⁻¹ (sample station 1) at the surface level with a mean value of 0.05 dS∙m⁻¹ and from 0.042 dS∙m⁻¹ (sample station 7) to 0.09 dS∙m⁻¹ (sample station 2) at the sub surface level. The electrical conductivity value of this soil is non saline. These values are within the tolerance levels for plant growth. Electrical conductivity tolerance levels for plants growing on soils have been set at 4000 µs/cm (4 dS∙m⁻¹) in the saturated soil extract [19] .

Soil organic C usually mixed up with fine clay particles to form soil colloids. It’s an important soil fraction due to its binding properties that enhanced most physical and chemical activities in the soil [20] . Thus, there is increased contact with other colloids and with soil solution. The TOC varies significantly (p < 0.001). Pair-wise mean difference showed significantly higher TOC on the surface soil compared to the subsurface. About 80% of stations sampled had TOC less than 1% in the subsurface soil. This result implies that there is a strong friction and cohesion bonds between particles and soil water, and it is imperative that soil at the 0 - 15 cm depth holds aggregates together better than a sandy soil subsoil when wet. Total organic C reduced downward by 68.8% from the surface soil. It ranged from 1.12 (Station 7) to 5.34% (station 2) averaged 2.70% at the surface level and from 0.270 (Station 5) to 1.20% (Stations 3 & 7), with a mean value of 0.84% at the sub surface level. The ground biomass on the surface soil contributed more than 37% to the TOC compared to the subsurface soils. For an overall view, this site is low in organic C, and this could be attributed to high C sequestration associated with poor soil management that decreases TOC content of the soil.

Total nitrogen content of the surface soil in the study area is low (<0.10%). The mean values are 0.07% and high on the subsurface with a mean value of 0.50%, while range of values are from 0.03 (Station 7) to 0.13% (station 2) for surface soils and 0.15 (Station 9) to 0.88% (Station 5) for subsoils. The high total nitrogen contents of the subsoils are attributable to the high organic matter contents at this depth. The amount of N in the soil is an indication of how suitable the soils environmental conditions are, and the content in this study site could be classified as very low to high concentration.

Phosphorus is one of the nutrients that is very essential for plant growth. However not all the total phosphorus in the soil is available for plant uptake [21] . This is because phosphorus occurs in soil matrix either in the occluded or solution form. Only the solution form of phosphorus is available for plant uptake. Most of the phosphorus in tropical soils that are available for plant uptake is induced by microbial activities in the soil. Thus phosphorus availability is also affected by soil environmental factors that affect microbial activities. Available phosphorus content of soils from the study area is high on the surface (>8.00 mg/kg) The Phosphorus contents ranged from 29.3 mg/kg (Station 6) to 49.5 mg/kg (sample station 5) at the surface soil level and from 0.71 mg/kg (sample station 8) to 1.56 mg/kg (sample station 5) at the subsurface soil level. The phosphorus content decreased down the depth and is considered low (<8 mg/kg) at the subsurface level.

Cation exchange is important reaction in soil fertility; in correcting soil acidity and basicity, in altering soil physical properties and as a mechanism in purifying percolating waters [22] . The exchangeable cations (bases) (Ca, Mg, Na and K) of the soils of the study area are high and the exchange complex is dominated by Ca (surface soils: 3.54 cmol∙kg⁻¹; subsoils: 3.44 cmol∙kg⁻¹ soil), followed by Mg (surface soils: 1.52 cmol∙kg⁻¹; subsoils: 2.55 cmol∙kg⁻¹), K (surface soils: 0.12 cmol∙kg⁻¹; subsoils: 0.11 cmol∙kg⁻¹) and Na (surface soils: 0.06 cmol∙kg⁻¹; subsoils: 0.16 cmol∙kg⁻¹).

However, any flowing water in this soil will lose its soluble cations (Ca and Mg) to the exchange site. This reduces the leaching loss and their mobility in the soil. The disadvantage is that, should any potential pollutants, such a Pb or Cd is disposed to this soil, instead of leaching easily, the will be adsorbed to the cation exchanged sites. Therefore, deposition of materials with heavy metal contents should be properly guided.

At the same time, higher Ca and Mg availability in the soil solution facilitate the association between clay and sand (r = 0.841 and −0.767 surface and subsurface respectively), which is supported by the high correlation observed between TOC and the K (−0.820), Ca and ECEC (0.867) contents on the surface soils. The formation of cation chemical bonds between TOC and ECEC is a common mechanism of SOM stabilization, and Ca is very important in the establishment of these bonds [23] . Hence, these chemical bonds between the TOC and the minerals of these soil fractions constitute a chemical protection of the organic compounds, impeding their decomposition [20] .