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Background:Soil properties are anisotropic in nature, hence the need to study soil associations and regional landscapes for sustainable nutrient management and soil profile is an important tool which can be utilized for this purpose.Objective:The objectives of the study are to describe the morphology of the soils of the toposequence, determine their physical and chemical properties, classify them and make an appraisal of their agricultural potentials.Methods:Three slope classes were considered and a total of three profile pits, one on each slope were studied and described in the field morphologically at Eleyin Farms Omu-Aran, Kwara State, Nigeria, which was a newly opened up plantation.Samples of soil were collected from the horizons of the profile pits. The soil samples were analyzed for their physical and chemical properties.Results:All the three pedons showed appreciable differences in physical, chemical, and morphological characteristics of the soils and their classifications were determined as guided by their characteristics. The textural classes were defined mainly by the sand compositions which decreased from the upper and middle slopes down to the bottom slope, and the clay compositions which increased progressively from the uppermost slope through the middle slope to the bottom slope. Silt compositions did not exhibit any particular pattern.Conclusion:Thus, sand and clay compositions were more significant and relevant to the textural classification of the soils of the area than silt. The low nutrient status of the soils can be ameliorated by incorporation of organic or farm residues to increase the organic matter content of the soil, and also improve management practices and guided chemical fertilizer use. The soils of the area were classified as Typic Haplustalf (USDA), and Ferric Luvisol (FAO).

Farmers have not tested their soils for nutrient status and therefore are unaware of the fertility status of their soils. Therefore, a baseline fertility survey of 50 hectares of land of a gravelly Alfisol in the Teaching and Research Farm of Landmark University, Omu-Aran, Kwara State, Nigeria was carried out with a view to identifying soil health constraints and site-specific sustainable land management practices for optimizing crop production. Standard field protocols and laboratory analytical procedures were employed for all sample parameters measured. Results show that the soil textural classes vary from sand to loamy sand, exchangeable acidity, Ca, Mg, K, and Na and the effective cation exchange capacity has the surface and subsurface soil values of 0.0–0.92 and 0.00–0.89 cmol kg−1, 1.6–7.7 and 2.0–5.8 cmol kg−1, 1.2–11.5 and 0.7–8.0 cmol kg−1, 0.09–0.33 and 0.09–0.43 cmol kg−1, 0.0–0.16 and 0.04–0.16 cmol kg−1, 7.2–12.10 and 0.9–12.5 cmol kg−1, respectively. P values lie in the ranges of 2.5–68.9 mg kg−1 and 2.0–37.7 mg kg−1 in the surface and subsurface soils, respectively, organic C values were 0.86–2.81% and 0.68–3.49%, respectively, in the surface and subsurface soils while the values of N were 0.12–0.61% in the surface and 0.11–0.56% subsurface soils. Land evaluation shows that the soils of the project site are very fragile and poor in native fertility. Compound fertilizers low in nitrogen contents but high in phosphorus and potassium are recommended for gravelly Alfisol in a derived savannah ecological zone of the Kwara State, Nigeria to avoid a nutrient imbalance that may create artificial deficiencies of otherwise adequate nutrient elements.

A field experiment was conducted at the Teaching and Research Farms of Landmark University Omu-Aran, Kwara State of Nigeria, for comparative evaluation of inorganic fertilizer with sole and integrated forms of cocoa pod ash (CPA) and cocoa pod husk powder (CPHP) on soil chemical properties, growth and yield of cucumber in Southern Guinea Savannah Zone of Nigeria. The treatments used for the experiment were control, NPK 20:10:10 (200 kg/ha), 100 % CPA (10 t/ha), 100 % CPHP (10 t/ha), 100 % CPA (10 t/ha) + 100 % CPHP (10 t/ha), 100 % CPA (10 t/ha) + 50 % CPHP (5 t/ha), 50 % CPA + 100% CPHP, and 50 % CPA + 50 % CPHP. At two weeks after planting NPK 20:10:10 was applied to the assigned plots at the rate of 200 kg/ha. Treatments were arranged in Randomised Complete Block Design (RCBD), replicated three times. Data collected were subjected to analysis of variance using SPSS procedure while DMRT at 5% level of probability was used to separate the means. Results showed that treatment with 10 t/ha CPA + 10 t/ha CPHP increased soil chemical properties compared to control. Treatments with 100% CPA + 100% CPHP and 100% CPA + 50% CPHP gave significantly higher and similar values of plant height, number of leaves, number of lateral branches and other yield parameters (fruit number, fruit length, fruit girth, fruit weight and total yield) of cucumber compared to the control. Therefore, the application of 10 t/ha CPA + 5 t/ha CPHP was considered best for growing cucumber in the study area. These cocoa wastes are readily available and eco-friendly compared to NPK that is costly and which may have adverse effect on the environment.

Background: In derived savanna ecology, the evaluation of soil characteristics for the current and future capability and suitability for crop production is crucial. Therefore, studies were conducted to evaluate the capability and suitability of plinthic soil of a derived savannah ecology of Nigeria for sustainable crop production. Methods: The methodology was essentially Grid using hand-held GPS to determine the coordinates of sampling points for the collection of soil samples. In all, 18 profile pit samples were collected. The profile pits were described morphologically on the field using the FAO guideline on soil profile description. From the various horizons of these profile pits, soil samples were collected. Results: Land assessment indicates that the soils of the area are very fragile and inherently low in nutrients. Mapping unit A is moderately suitable for arable crop production while Units B and C are fairly suitable. For agricultural activities, mapping unit D is marginal for arable crop production. Stoniness, steep slope, and shallow soil depth are the major limitations. Mapping unit E is the most suitable for lowland rice production. Soil fertility management ought to be integrated (organic and inorganic). The land evaluation shows that the soils of the project site are very fragile and poor in native fertility. Also, the soils are generally defined by the plinthite content. Apart from the traditional crops grown in the area, some other crops like sweet potato and cowpea will do well on the soil of the area. Crop residue has to be well managed and adopted. Crop rotation and intercropping should be encouraged and included in the soil management plan. Also, due to the low level of organic carbon in the soils, the soils will benefit optimally from the application of manure. This will improve the soil aggregation, water, and nutrient-holding capacities as well as improve the pH status of the soil. Conclusion: Soil fertility assessments should be undertaken every two years after continuous cropping. ’High-Intensity Detailed Soil Survey’ of this nature should be carried out every ten years.