Lack of detailed soil data has been a major constraint to hydrological modeling and making of agronomic decisions in the Koupendri Catchment. A soil survey was carried out to characterize and classify the soils of the 11.8 km 2 catchment using Soil and Terrain (SOTER) approach. The soils were classified using the soil taxonomy (USDA) and the world reference base for soil resources (WRB) classification systems. The soil map produced at a scale of 1:25000 using FAO/UNESCO legend showed five distinct soil types. The dominant soil type-Dystric Plinthosols-covered about 55% of the area and supports few crop productions but make plantation agriculture almost impossible. The soils are slightly acidic to alkaline, predominantly silty to clayey in texture with good to imperfect drainage, low permeability and high bulk density that impedes root growth. The poor soil organic carbon content, total nitrogen, available phosphorus, cation exchange capacity, base saturation and other basic exchangeable cations with moderately leached horizons indicated low-moderate fertility status of less weathered soils. The soils belong to three major soil orders: Ultisols, Inceptisols and Alfisols (USDA), and reference soil groups: Plinthosols, Cambisols, Luvisols and Gleysols (WRB). The WRB gave a better and detailed soil classification compared to USDA, and thus should be used in subsequent classification of soils in the region.

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Background: The greenhouse and field studies were carried out to assess the effect of different rates of poultry manure (PM), pig slurry (PS) and the recommended NPK fertilizer on some soil physico-chemical properties and okra yield of coarse-textured Ultisols in Nsukka, southeastern Nigeria. Methods: The PM and PS were applied at three different rates (10, 20 and 40 t ha-1) as well as no amendment as control and the recommended NPK fertilizer (300 kg/ha) and replicated five times. Soil and agronomic data collected were analyzed for variance (ANOVA) using Genstat 4.0.Result: The PM and PS significantly (p less than 0.05) improved soil pH, soil organic matter, available phosphorous, total nitrogen, aggregate stability, mean weight diameter, bulk density, porosity and saturated hydraulic conductivity in greenhouse and field studies. Significant improvement in CEC was obtained in the field study. The PM and PS significantly (p less than 0.05) improved agronomic parameters e.g. plant height, number of leaves, biomass weight and yield of okra than the control. Poultry manure showed its superiority over other amendments in improving soil and agronomic properties. The study recommended 20 t ha-1 of PM and 40 t ha-1 of PS for sustainable soil and optimum productivity of okra in Nsukka, southeastern Nigeria.

The spatial distribution of soil properties especially saturated hydraulic conductivity (Ksat), Bulk density (BD), soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (Avail.P) is fundamental to sustainable management of soil resources. About 291 surface soil (0-20 cm) samples were collected across three land use types (maize-sorghum (MS), rice field and fallow shrub-grassland (FSG) in Koupendri, north-west Benin using a grid sampling of 25 m x 25 m supplemented with samplings at 5 m x 5 m. Data obtained were subjected to classical and spatial statistics, Pearson’s correlation and analysis of variance using GENSTAT. The soil properties showed normal and non-normal distribution, variation was high (75-126.7 %) for Ksat, moderate (29-45 %) for SOC, C/N and Avail.P, and low (7-15) for BD and TN across the land use. Land use had significant (P < 0.05) effect on all the soil properties evaluated except C/N. The highest values of Ksat (151.6 cm/d), SOC (1.26 %), BD (1.79 g/cm³), TN (0.105 %), Avail.P (4.66 ppm) and C/N (12.14) were obtained under the MS cropland whereas porosity was highest (43.7 %) in the rice field. High significant correlation (P < 0.01) was observed among the soil properties irrespective of land use.  The correlation length (65-300 m) and nugget effect ratio indicates high variation and strong spatially dependent soil properties. However, TN, BD, Avail.P and C/N were weakly spatially dependent. The variograms were fitted with mostly exponential and spherical models. The interpolation map could help in delineating different management zones and for making good agronomic decisions.