Effect of combined use of supplementary irrigation, manure and P fertilization on grain yield and profitability of soybean in northern Nigeria.

Declining soil fertility particularly phosphorus deficiency, low organic carbon, moisture stress and high cost of input are factors limiting soybean yield in the Nigeria savanna. Supplementary irrigation, nutrient application and inoculation with Bradyrhizobium could increase the grain yield of soybean. We evaluated the effects of Rhizobia inoculant, phosphorus fertilization, manure, and supplementary irrigation on the nodulation and productivity of a tropical soybean variety in two locations in northern Nigeria in the 2017 and 2018 cropping seasons. The treatments consisted of five input bundles: Supplementary irrigation +17.5 kg P ha-1 + 4 t ha-1 poultry manure + nodumax inoculant (S + P + M + I); 17.5 kg P ha-1 + 4 t ha-1 poultry manure + nodumax inoculant (P + M + I); 17.5 kg P ha-1 + nodumax inoculant (P + I); 17.5 kg PP ha-1 (P); and nodumax inoculant (I). Economic analysis was done to determine the benefit-cost ratio (BCR) for each input bundle. In Kano, the input bundle S + P + M + I produced mean number of nodules that were 38, 102, 200 and 352% higher than that of input bundles P + M + I, P + I, P and I, respectively. At Lere, the application of input bundle S + P + M + I increased mean number of nodules by 33, 81, 93 and 182% over that of input bundles P + M + I, P + I, P and I, respectively. Mean grain yield in Kano was greater for input bundle S + P + M + I over P + M + I, P + I, P and I bundles by 31, 50, 64 and 223%, respectively. In Lere, grain yield for input bundle S + P + M + I was higher than that of input bundles P + M + I, P + I, P and I only, by 27, 47, 41 and 184% respectively. The input bundle P + M + I produced the highest BCR (1.4) in Kano and application only of P produced the highest BCR (1.3) in Lere. Supplementary irrigation was not found to be profitable due to the high cost of supplementary irrigation.The application of P with or without manure/inoculant is recommeded for profitable soybean production in the savannas of Nigeria.

Assessment of the impact of crop management strategies on the yield of early-maturing maize varieties in the drylands of Niger Republic: Application of the DSSAT-CERES-Maize model.

Maize is increasingly becoming important in Niger for use as food and feed. Production is however, faced with several abiotic and biotic constraints. Researchers have developed early-maturing maize varieties that are tolerant to drought, the parasitic weed Striga hermonthica and diseases that fit into the short growing production environment. The evaluation and deployment of these varieties would, however, involve costly and time-consuming field trials across the maize production zones of the country. The CERES-Maize model was applied to assess the performance of two early-maturing maize varieties under varying planting windows and nitrogen application in three agroecological zones of the country. The model was calibrated with datasets collected from field trials conducted under optimal conditions (supplementary irrigation and full nutrient supply) at three locations in northern Nigeria. The model was validated with independent data set obtained from field trials conducted in 2020 and 2021 at 4 locations in the Republic of Niger under rainfed conditions. For each variety the treatments were five nitrogen (N) rates (0, 30, 60, 90 and 120 kg ha-1). The results from model calibration and validation revealed that the model accurately reproduced the observed value for days to flowering, physiological maturity, aboveground dry biomass and grain yield with low nRMSE (0.4-12.7%) and high d-index (0.70-0.99) for both varieties. The long-term simulation results (1985-2020) showed that the maize performance was dependent on location, planting window and nitrogen rates. The variety 2014 TZE-Y yielded higher than Brico in all locations for all treatments because it takes longer to mature and accumulate higher dry matter and have higher number of kernels. Simulated yields were generally higher in the Sudan savanna agroecological zone than in the other zones because of higher rainfall and higher clay content of the soil in this zone. The response to N application was influenced by planting window in each agroecological zone. With the exception of two sites, grain yield declined with planting beyond July 14 (PW3) and response to N was not significant beyond this date in the Sudan savanna agroecological zone. Grain yield declined with planting beyond July 7 in the Sahel and Sudan Sahel agroecological zones. There was no further response to N beyond 30 and 60 kg N ha-1 when planting is delayed beyond July 7 in the Sahel and Sahel-Sudan agroecological zones, respectively.

Evaluation and application of the CROPGRO-soybean model for determining optimum sowing windows of soybean in the Nigeria savannas.

Soybean production is limited by poor soil fertility and unstable rainfall due to climate variability in the Nigeria savannas. There is a decline in the amount and duration of rainfall as one moves from the south to north of the savanna zones. The use of adapted soybean varieties and optimum sowing windows are avenues to increase productivity in the face of climate variability. Crop simulation models can be used as tools for the evaluation of alternative management options for a particular location, including fertilizer application rates, plant density, sowing dates and land use. In this study, we evaluated the performance of the Cropping System Model (CSM)-CROPGRO-Soybean to determine optimum sowing windows for three contrasting soybean varieties (TGX1835-10E, TGX1904-6F and TGX1951-3F) cultivated in the Nigeria savannas. The model was calibrated using data from ten field experiments conducted under optimal conditions at two sites (BUK and Dambatta) in Kano in the Sudan savanna (SS) agro-ecology over four growing seasons. Data for model evaluation were obtained from independent experiment for phosphorus (P) response trials conducted under rainfed conditions in two locations (Zaria and Doguwa) in the northern Guinea savanna (NGS) zone. The model calibration and evaluation results indicated good agreement between the simulated and observed values for the measured parameters. This suggests that the CROPGRO-Soybean model was able to accurately predict the performance of soybean in the Nigeria savannas. Results from long-term seasonal analysis showed significant differences among the agro-ecologies, sowing windows and the soybean varieties for grain yield. Higher yields are simulated among the soybean varieties in Zaria in the NGS than in Kano the SS and Jagiri in the southern Guinea savanna (SGS) agro-ecological zones. Sowing from June 1 to July 5 produced optimal yield of TGX1951-3F and TGX1835-10E beyond which yield declined in Kano. In Zaria and Jagiri the simulated results show that, sowing from June 1 to July 12 are appropriate for all the varieties. The variety TGX1951-3F performed better than TGX1904-6F and TGX1835-10E in all the agro-ecologies. The TGX1951-3F is, therefore, recommended for optimum grain yield in the savannas of northern Nigeria. However, the late maturing variety TGX1904-6F is not recommended for the SS due to the short growing season in this zone.

CERES-Maize model for simulating genotype-by-environment interaction of maize and its stability in the dry and wet savannas of Nigeria.

When properly calibrated and evaluated, dynamic crop simulation models can provide insights into the different components of genotype by environment interactions (GEIs). Modelled outputs could be used to complement data from multi-environment trials. Field experiments were conducted in the rainy and dry seasons of 2015 and 2016 across four locations in maize growing regions of Northern Nigeria using 16 maize varieties planted under near-optimal conditions of moisture and soil nitrogen. The CERES-Maize model was calibrated using data from three locations and two seasons (rainy and dry) and evaluated using data from one location and two seasons all in 2015. Observed data from the four locations and two seasons in 2016 was used to create eight different environments. Two profile pits were dug in each location and were used separately in the simulations for each environment to provide replicated data for stability analysis in a combined ANOVA. The effects of the environment, genotype and GEI were highly significant (p = 0.001) for both observed and simulated grain yields. The environment explained 67 % and 64 % of the variations in observed and simulated grain yields respectively. The variance component of GEI (13 % for observed and 15 % for simulated) were lower but still considerable when compared to that of genotypes (19 % for observed and 21 % for simulated). From the stability analysis of the observed and simulated grain yields using six different stability models, three models (ASV, Ecovalence, and Sigma) ranked Ife Hybrid as the most stable variety. The slope of the regression (bi) model ranked Sammaz 11 as the most stable variety, while the Shukla model ranked Sammaz 28 as the most stable variety. Long-term seasonal analysis with the CERES-Maize model revealed that early and intermediate maturing varieties produce high yields in both wet and dry savannas, early and extra-early varieties produce high yields only in the dry savannas, while late maturing varieties produce high yields only in the wet savannas. When properly calibrated and evaluated, the CERES-Maize model can be used to generate data for GEI and stability studies of maize genotype in the absence of observed field data.

Molecular detection of rabies virus strain with N-gene that clustered with China lineage 2 co-circulating with Africa lineages in Monrovia, Liberia: first reported case in Africa.

Despite a long history of dog-transmitted human rabies outbreaks in Liberia, West Africa, no reports exist of molecular characterisation of the causative lyssaviruses. This study investigated Rabies lyssavirus (RABV) strains isolated at the dog-human interface in Monrovia, Liberia 2016 and 2017, by reverse transcription polymerase chain reaction, using primers specific for the nucleoprotein (N) gene. Out of 20 specimens (19 dog brain samples and one human saliva) tested as suspected rabies cases, three (15%) were positive. Purified amplicons from all three positive specimens were sequenced in both forward and reverse directions. Phylogenetic analysis was conducted in MEGA7 and PhyML3 to determine their relationship with RABV sequences accessioned in NCBI GenBank. The first of three RABV strains detected clustered with China lineage 2 RABVs of dogs (99% homology to KU963489 and DQ666322). The second strain segregated with Africa lineage 2 RABVs also of dog origin, and the third strain segregated with Africa lineage 3 RABVs of Southern Africa viverrids. Our results show a transcontinental strain of rabies virus co-circulating with Africa lineages in post-conflict Liberia. This finding should stimulate more effective sub-regional planning and execution of one-health actions, towards stepwise surveillance and elimination of rabies in West Africa by 2030.

Options for calibrating CERES-maize genotype specific parameters under data-scarce environments.

Most crop simulation models require the use of Genotype Specific Parameters (GSPs) which provide the Genotype component of G×E×M interactions. Estimation of GSPs is the most difficult aspect of most modelling exercises because it requires expensive and time-consuming field experiments. GSPs could also be estimated using multi-year and multi locational data from breeder evaluation experiments. This research was set up with the following objectives: i) to determine GSPs of 10 newly released maize varieties for the Nigerian Savannas using data from both calibration experiments and by using existing data from breeder varietal evaluation trials; ii) to compare the accuracy of the GSPs generated using experimental and breeder data; and iii) to evaluate CERES-Maize model to simulate grain and tissue nitrogen contents. For experimental evaluation, 8 different experiments were conducted during the rainy and dry seasons of 2016 across the Nigerian Savanna. Breeder evaluation data were also collected for 2 years and 7 locations. The calibrated GSPs were evaluated using data from a 4-year experiment conducted under varying nitrogen rates (0, 60 and 120kg N ha-1). For the model calibration using experimental data, calculated model efficiency (EF) values ranged between 0.88-0.94 and coefficient of determination (d-index) between 0.93-0.98. Calibration of time-series data produced nRMSE below 7% while all prediction deviations were below 10% of the mean. For breeder experiments, EF (0.58-0.88) and d-index (0.56-0.86) ranges were lower. Prediction deviations were below 17% of the means for all measured variables. Model evaluation using both experimental and breeder trials resulted in good agreement (low RMSE, high EF and d-index values) between observed and simulated grain yields, and tissue and grain nitrogen contents. It is concluded that higher calibration accuracy of CERES-Maize model is achieved from detailed experiments. If unavailable, data from breeder experimental trials collected from many locations and planting dates can be used with lower but acceptable accuracy.

Evaluation of a rapid and sensitive RT-qPCR assay for the detection of Ebola Virus.

BACKGROUND: The 2013-2016 Ebola virus disease (EVD) outbreak showed a lack of diagnostic point-of-care methods. Currently, EBOV diagnosis relies on quantitative reverse-transcription-PCR (RT- qPCR), highly specific and sensitive, but requiring skilled personnel and well-equipped laboratories. In field settings, these factors and others, such as samples' time of collection and transportation, determine a prolonged turnaround-time to final results. In outbreak scenarios, a rapid and transportable method could eliminate issues of cohorting suspected and actual EVD patients for lack of diagnostic certainty. The aim of this study was the field evaluation of the new fast, easy-to-use and reliable RT-qPCR assay and platform for EBOV detection, developed in the framework of the EbolaMoDRAD project by CLONIT S.r.l. and STMicroelectronics S.r.l. STUDY DESIGN: We evaluated its performance during the outbreak and in further studies in the EVD laboratory at the Princess Christian Maternity Hospital (PCMH) in Freetown (Sierra Leone) run by Emergency NGO and the Italian National Institute for Infectious Diseases (INMI). The assay was tested on residual aliquots of clinical specimens from EBOV-positive or -negative patients (n=116, EVD prevalence 37%). RESULTS AND CONCLUSION: Overall, the test was very easy-to-use and the instrument was robust and reliable in field-settings. The sensitivity of the assay was 100% and the specificity was 98.63% (95%CI: 96.34-100.92%). The positive and negative predictive values were 97.73 (95%CI:94.77-100.68%) and 100%, respectively. The high sensitivity and specificity of this new assay indicate that it is promising for laboratory diagnosis, especially in resource-limited settings.

EBOLA Ag K-SeT rapid test: field evaluation in Sierra Leone.

OBJECTIVES: Efficient interruption of Ebola virus disease (EVD) transmission chains critically depends on reliable and fast laboratory diagnosis. We evaluated the performance of the EBOLA Virus Antigen Detection K-SeT (EBOLA Ag K-SeT), a new rapid diagnostic antigen test in field settings. METHODS: The study was conducted in a field laboratory located in Freetown (Sierra Leone) by the Italian National Institute for Infectious Diseases 'L. Spallanzani' and the EMERGENCY Onlus NGO. The EBOLA Ag K-SeT was tested on 210 residual plasma samples (EVD prevalence 50%) from patients hospitalized at the EMERGENCY Ebola treatment center in Goderich (Freetown), comparing the results with quantitative real-time PCR. RESULTS: Overall, the sensitivity of EBOLA Ag K-SeT was 88.6% (95% confidence interval (CI), 82.5-94.7), and the corresponding specificity was 98.1% (95% CI, 95.5-100.7). The positive and negative predictive values were 97.9% (95% CI, 95.0-100.8) and 89.6% (95% CI, 84-95.2), respectively. The sensitivity strongly increased up to 98.7% (95% CI, 96.1-101.2) for those samples with high virus load (≥6.2 log RNA copies/mL). CONCLUSIONS: Our results suggest that EBOLA Ag K-SeT could represent a new effective diagnostic tool for EVD, meeting a need for resource-poor settings and rapid diagnosis for individuals with suspected EVD.

Looking back and moving forward: 50 years of soil and soil fertility management research in sub-Saharan Africa.

Low and declining soil fertility has been recognized for a long time as a major impediment to intensifying agriculture in sub-Saharan Africa (SSA). Consequently, from the inception of international agricultural research, centres operating in SSA have had a research programme focusing on soil and soil fertility management, including the International Institute of Tropical Agriculture (IITA). The scope, content, and approaches of soil and soil fertility management research have changed over the past decades in response to lessons learnt and internal and external drivers and this paper uses IITA as a case study to document and analyse the consequences of strategic decisions taken on technology development, validation, and ultimately uptake by smallholder farmers in SSA. After an initial section describing the external environment within which soil and soil fertility management research is operating, various dimensions of this research area are covered: (i) 'strategic research', 'Research for Development', partnerships, and balancing acts, (ii) changing role of characterization due to the expansion in geographical scope and shift from soils to farms and livelihoods, (iii) technology development: changes in vision, content, and scale of intervention, (iv) technology validation and delivery to farming communities, and (v) impact and feedback to the technology development and validation process. Each of the above sections follows a chronological approach, covering the last five decades (from the late 1960s till today). The paper ends with a number of lessons learnt which could be considered for future initiatives aiming at developing and delivering improved soil and soil fertility management practices to smallholder farming communities in SSA.

Assessment of the severity of Ebola virus disease in Sierra Leone in 2014-2015.

The current Ebola virus disease (EVD) epidemic in West Africa is unprecedented in scale, and Sierra Leone is the most severely affected country. The case fatality risk (CFR) and hospitalization fatality risk (HFR) were used to characterize the severity of infections in confirmed and probable EVD cases in Sierra Leone. Proportional hazards regression models were used to investigate factors associated with the risk of death in EVD cases. In total, there were 17 318 EVD cases reported in Sierra Leone from 23 May 2014 to 31 January 2015. Of the probable and confirmed EVD cases with a reported final outcome, a total of 2536 deaths and 886 recoveries were reported. CFR and HFR estimates were 74·2% [95% credibility interval (CrI) 72·6-75·5] and 68·9% (95% CrI 66·2-71·6), respectively. Risks of death were higher in the youngest (0-4 years) and oldest (⩾60 years) age groups, and in the calendar month of October 2014. Sex and occupational status did not significantly affect the mortality of EVD. The CFR and HFR estimates of EVD were very high in Sierra Leone.

Evaluation of a point-of-care blood test for identification of Ebola virus disease at Ebola holding units, Western Area, Sierra Leone, January to February 2015.

Current Ebola virus disease (EVD) diagnosis relies on reverse transcription-PCR (RT-PCR) technology, requiring skilled laboratory personnel and technical infrastructure. Lack of laboratory diagnostic capacity has led to diagnostic delays in the current West African EVD outbreak of 2014 and 2015, compromising outbreak control. We evaluated the diagnostic accuracy of the EVD bedside rapid diagnostic antigen test (RDT) developed by the United Kingdom's Defence Science and Technology Laboratory, compared with Ebola virus RT-PCR, in an operational setting for EVD diagnosis of suspected cases admitted to Ebola holding units in the Western Area of Sierra Leone. From 22 January to 16 February 2015, 138 participants were enrolled. EVD prevalence was 11.5%. All EVD cases were identified by a positive RDT with a test line score of 6 or more, giving a sensitivity of 100% (95% confidence interval (CI): 78.2-100). The corresponding specificity was high (96.6%, 95% CI: 91.3-99.1). The positive and negative predictive values for the population prevalence were 79.0% (95% CI: 54.4-93.8) and 100% (95% CI: 96.7-100), respectively. These results, if confirmed in a larger study, suggest that this RDT could be used as a 'rule-out' screening test for EVD to improve rapid case identification and resource allocation.

Does a Post-take Ward Round Proforma Lead to Sustainable Improvements in Quality of Documentation for Patients Admitted to the Medical Assessment Unit?

This study assessed the quality of post-take ward round (PTWR) documentation, specifically looking at twelve criteria, in the medical assessment unit (MAU) prior to, 3- months and 2-years after introducing a PTWR proforma. 216 case records were analysed; 40 prior to, 40 three-months and 146 two-years after introducing the PTWR proforma. There was a significant improvement in eight criteria threemonths after introducing the PTWR proforma. These improvements were sustained two-years later and significant improvements made in a further 3 criteria (1 at p < 0.05 and 2 at p ) 0.01).

Developing a network: the PMM process.

Since 1988, the Prevention of Maternal Mortality (PMM) Network has developed, implemented and evaluated projects that focus directly on prevention of maternal deaths. The Network, which consists of 11 multidisciplinary teams in West Africa and one at Columbia University, grew from discussions between the Carnegie Corporation of New York and researchers at Columbia School of Public Health. Its goals are: to strengthen capacities in developing countries; to provide program models for preventing maternal deaths; and to inform policymakers about the importance of maternal mortality. This paper describes the development and functioning of the Network. The initial steps included identifying interested partners in Africa and encouraging them to form multidisciplinary teams. Each African team received two grants: one to perform a needs assessment and then another to develop and implement projects based on the results. The Columbia team provided technical assistance in a variety of ways, including site visits, workshops and correspondence. Teams tested program models and reported findings both to local policymakers and in international fora. Collaboration with government and community leaders helped facilitate progress at all stages. At the PMM Network Results Conference in 1996, the teams decided to continue their work by forming the Regional PMM (RPMM) Network, an entirely African entity.

Lessons learned from the PMM Network experience.

For eight years, the Prevention of Maternal Mortality (PMM) Network in West Africa designed, implemented and evaluated projects to reduce barriers to care for women with obstetric complications. Many valuable lessons were learned concerning program development and implementation. A multidisciplinary approach enabled the Network to address the various aspects of the problem; collaboration between teams encouraged the sharing of resources and experiences; and collaboration with government and communities enhanced project sustainability. Capacity building through long-term, systematic technical support resulted in a Network of proficient researchers. Existing human and material resources were utilized to enhance the feasibility and sustainability of projects--a strategy that could be adopted in other developing countries. Cost-tracking was used as a management and evaluation tool. The collective experience of the Network offers guidance for program planners and researchers working on maternal mortality in developing countries.

Pneumococcal resistance in southwest Virginia.

Resistance patterns of Streptococcus pneumoniae in southwest Virginia were determined for 100 consecutive, hospital-based isolates, mostly from adults. Oxacillin disk screening identified all resistant isolates. Sixteen percent of the isolates were penicillin resistant (10% were highly resistant). E-strip testing revealed the following MICs (in micrograms per milliliter, with percentages of isolates in parentheses): cefotaxime, < or = 0.5 (92%); ceftriaxone, < or = 0.5 (95%); ceftizoxime, < or = 0.5 (85%); erythromycin, < or = 1 (87%); ofloxacin, < or = 2 (80%); vancomycin, < or = 1 (98%).

A reexamination of the effects of intracerebroventricular glucocorticoids in adrenalectomized rats.

Several investigators have reported that many of the behavioral and metabolic effects of ADX can be reversed by appropriate levels of glucocorticoids administered either peripherally or centrally. The present studies were conducted to offer a comparison of the effects of orally administered corticosterone (CORT) with ICV glucocorticoids [CORT, CORT acetate, or dexamethasone (DEX)]. Of particular interest were the effects of glucocorticoid treatment on body weight gain and on macronutrient self-selection. Adult male Sprague-Dawley rats were fitted with ICV cannulae and either bilaterally ADX or given sham operations. In the first experiment, ADX animals were initially treated systematically with CORT (20 micrograms/ml in their drinking water). After a wash-out period during which no steroids were administered, ADX rats were given daily ICV CORT injections (100 micrograms/day in 10 microliters). Systemic CORT treatment promotes weight gain and normal food choice patterns in ADX rats. ICV injections failed to promote weight gain in ADX rats, and daily injection of the vehicle promoted a weight loss in sham-operated controls. Four additional experiments were conducted. ADX, glucocorticoid-treated animals and ADX, vehicle-treated controls as well as sham-operated, vehicle-treated controls were used to assess the effects of both steroid and vehicle on body weight gain and dietary selection patterns. ADX ICV-glucocorticoid-treated animals typically failed to gain weight at the rate observed when ADX rats are treated with CORT systematically. Under one condition, ADX-CORT-treated animals gained weight at a rate comparable to untreated controls, but their ICV-injected control group failed to gain weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of specificity of polyunsaturated fats in the inhibition of rat liver glucose-6-phosphate dehydrogenase.

The mechanism of the effect of polyunsaturated fatty acids (PUFA) on glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (G6PDH) was studied in young, male Wistar rats. Starvation-refeeding increased G6PDH level above that seen in ad libitum-fed animals (enzyme overshoot). A second episode of starvation-refeeding produced even higher levels of G6PDH activity (induction increment). Interposing a high fat diet (containing PUFA) between starvation and feeding the inducer diet abolished one-half to two-thirds of the overshoot. Feeding a high fat diet between the two starvations abolished the induction increment. Inhibitors of arachidonic acid metabolism were not able to reverse the PUFA effect. In another set of experiments it was shown that both linoleic and linolenic acid are equally effective in either reducing the overshoot or abolishing the induction increment. The evidence was interpreted as supporting a hypothesis that the PUFA effect does not require the formation of a specific end product of arachidonic metabolism in a direct way.