Low soil phosphorus levels in savanna soils of Ghana limit cowpea response to inoculation. A two-year experiment was carried out on 2 soil types of the Guinea and Sudan savanna zones of Ghana based on the hypothesis that Bradyrhizobia inoculant (BR3267) in combination with phosphorus and potassium fertilizer will significantly increase cowpea root nodulation, growth and yield. The study aimed to determine the effect of phosphorus and potassium fertilizer on cowpea response to Bradyrhizobia inoculant. The treatments were laid out in Randomized Complete Block Design, replicated four times. The plot size was 8 × 3 m, with the sowing distance of 60 × 20 cm. The treatment comprises of commercial Bradyrhizobia inoculant, phosphorus (0, 30, 40 kg P₂O₅ ha⁻¹) and potassium (0, 10, 20, 30 K₂O ha⁻¹). Application of Bradyrhizobia inoculant with 30 kg P₂O₅ ha⁻¹ and 20 kg K₂O ha⁻¹ gave the highest grain yield (1.68 and 1.86 tons ha⁻¹) at both soils which did not differ from the yield obtained from BR-40-30 kg ha⁻¹ P₂O₅ and K₂O ha⁻¹ on the Ferric Lixisol and BR-40-20 kg ha⁻¹ P₂O₅ and K₂O on the Ferric Luvisol. The same treatment also gave the highest nodule number and nodule dry weight. The results of this study have shown that the application of Bradyrhizobia inoculant followed by P and K fertilizer was effective for cowpea growth in field conditions.

Water is considered as an important resources for human existence on the earth. In order to simulate or optimized hydrological data for various water resources management, several hydrological models are very useful to attain this aim for water resources management and as a decision support tools. A rainfall-runoff model is a quantitative prototype explaining the rainfall-runoff interactions at basin scale. The hydrological models have peculiarities in terms of capabilities for various water resources management. This paper tends to reviewed over fifty (50) papers that are peculiar to hydrological models as applicable to rainfall-runoff modeling. It involved evaluating and comparing different hydrological models used in simulating rainfall process converting into surface runoff for water use efficiency. Several runoff models such as Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS), Soil and Water Assessment Tool (SWAT), Precipitation-Runoff Modeling System (PRMS), Variable Infiltration Capacity model (VIC), LISt-based Erosion Model (LISEM), MIKE Surface Water - Groundwater Hydrology (MIKE SHE) and Runoff Prophet were critically assessed. Rainfall-runoff models are globally utilized for different applications to enhance water use efficiency across different sectors. However, types of hydrological models by examining various hydrological models, model accuracy by evaluating the accuracy and reliability of each model in predicting runoff from rainfall data, scope of applications by determining the adequacy of the models for numerous geographical regions and climatic circumstances, complexity and usability by assessing the complexity of the models, their data requirements, ease of use and computational efficiency, also the models advantages and limitations in capturing the dynamics of the rainfall-runoff process were critically assessed. This was to aid modeling objectives. It was inferred that HEC-HMS is widely applied for modelling precipitation-runoff processes in watersheds of various sizes, aiding in flood forecasting, reservoir operation, and water management for agricultural and urban water use efficiency. SWAT is used for assessing the impact of land management practices (e.g., crop rotation, irrigation, land use changes) on water resources, including runoff generation and water quality, thus optimizing water use efficiency in agriculture. PRMS is applied to model the transport of water via complex hydrological systems, aiding in watershed management and water use efficiency assessments. In conclusion, this comparative review seeks to guide water scientists, the users of hydrological models and hydrological engineers in selecting the most suitable models for their specific modelling needs for sustainable water resources management.

The effects of environmental factors, roof materials and age of roof on some metals usually found in Domestic Roof-Harvested Rainwater (DRHRW) from southern Nigeria were investigated. Samples were collected in Ibadan (residential), Lagos (industrial) and Port-Harcourt (gas-flaring). Four roof types (corrugated-iron-sheet, long-span-aluminium, asbestos and step-tiles) and three ages of roof (<5, 5–10 and >10 years in service conditions) were considered. Sample preparations, handling and analysis were carried out using standard procedures. Enrichment-Factor, Transfer-Factor and Pollution-Load-Index were estimated to identify roof polluting severity, rate of transfer of each metal detected into the DRHRW as well as atmospheric contribution to the overall pollution effects observed. Metal enrichment was generally low indicating low metal transfer into DRHRW from the sites. Occasional moderate enrichment was recorded for Fe, Cu, Zn, Ca and Mg suggesting their natural presence in the environment. Extremely high enrichment observed for Pb and Cd in industrial and gas-flaring rainwater samples as compared with residential indicated that metal contaminations in these locations are higher compared to residential samples which serve as background. Rate of metal transfer from roof material to rainwater was generally low. Thus, the possible source of the metal contaminants found in DRHRW in the areas investigated was the atmosphere. Mean Pollution-Load-Index of 0.95, 0.99 and 1.06 for rainwater samples in Ibadan, Lagos and Port-Harcourt areas respectively suggested higher pollution load in gas-flaring than residential and industrial regions. Pollution-Load-Index applied to age and roof-type indicated that long-span-aluminium and asbestos roofs that are less than 5 years could contaminate rainwater.

Elevated concentrations of metals in rivers can pose significant risks to human health. Consequently, it is essential to monitor metal levels in river water to minimize human exposure, particularly through consumption of harvested fish and other uses. This study examined the water quality of the Ona River in Ibadan, Nigeria. Seven potentially toxic elements (PTEs), namely Fe, Cu, Mn, Zn, Pb, Cd, Cr and four macronutrients: Mg, Na, K, Ca were investigated. Surface and pore water samples were collected from six sampling points during the peak of the dry and the rainy seasons. These were analyzed according to standard procedures and processed using the Simple Fuzzy Classification (SFC) model with four classes. The results revealed that the PTEs: Fe, Pb, Cd, Cr, and Mn were detected above guideline limits in several sampling points, indicating possible contamination from anthropogenic sources. Simple fuzzy classification puts the quality of water in the investigated portion of the river in the range of 67.4–88.5% in the C₁ (pristine) category during the dry season and 61.9–88.6% in C₁ (pristine) during rainy season. However, there were membership functions of up to 58.7 and 63.2; 61.2 and 75.4 as well as 44.3 and 43.5% in C₂, C_3, and C₄ categories (contaminated, polluted and extremely polluted, respectively) during the first and second sampling, respectively. Due to the high concentrations of toxic and bioaccumulative metals in the river, efforts should be made to control the discharge of pollutants into the river. These will prevent human health exposure risks tendencies for various uses, including fish production.