COVAD survey 2 long-term outcomes: unmet need and protocol

Vaccine hesitancy is considered a major barrier to achieving herd immunity against COVID-19. While multiple alternative and synergistic approaches including heterologous vaccination, booster doses, and antiviral drugs have been developed, equitable vaccine uptake remains the foremost strategy to manage pandemic. Although none of the currently approved vaccines are live-attenuated, several reports of disease flares, waning protection, and acute-onset syndromes have emerged as short-term adverse events after vaccination. Hence, scientific literature falls short when discussing potential long-term effects in vulnerable cohorts. The COVAD-2 survey follows on from the baseline COVAD-1 survey with the aim to collect patient-reported data on the long-term safety and tolerability of COVID-19 vaccines in immune modulation. The e-survey has been extensively pilot-tested and validated with translations into multiple languages. Anticipated results will help improve vaccination efforts and reduce the imminent risks of COVID-19 infection, especially in understudied vulnerable groups

Changes in annual, seasonal and monthly rainfall in Nigeria during 1961-90 and consequences to agriculture

The focus of this study is to provide baseline data for agricultural development activities in Nigeria, with emphasis on understanding the dynamics of spatial and temporal change in annual, seasonal and monthly rainfall during the past 30 years (1961-1990), using daily rainfall data. It was found that annual rainfall has declined in Nigeria over both time and space. The rainfall decline is unprecedented in duration and seasonal expression. The greatest change occurred in the onset of the rainy season and the extent of early rainfall, which has resulted in a reduction of the growing season by nearly one month and is likely to increase risk in early planting. There were fewer wet days and higher rainfall intensities in most of the country. This may cause erosion and emphasizes the need for improved measures to arrest erosion. There are also several agricultural technologies available that could help farmers reduce the negative impacts of rainfall on crop production

Nutrient recovery and productivity of a soybeanmaize rotation in the derived savanna ecology of West Africa

A researcher-managed on-farm experiment was conducted on a soil with low 1.90 mg/kg available phosphorus (P) to evaluate nutrient carryover from soybean grown under different P management options and productivity of maize grown in rotation. Promiscuously nodulating 110-day maturing soybean variety TGx 1479-1E was planted under eight fertilizer treatments comprising of two levels of nitrogen (N 0 and 60 kg ha−1) and four P (0,15, 30 and 60 kg ha−1) levels. In the following year, maize variety, DMLSR-Y was sown without fertilizer on soybean fallow plots with two bush fallow treatments at zero and 60 kg N ha−1 as checks for system efficiency evaluation. Soybean yields at N = 60 and 0 kg ha−1 could be described as Yield60 = 1407.2 + 31.159P − 0.3284P2, R2 = 0.99 and Yield0 = 1590.4 − 7.367P + 0.2694P2, R2 = 0.96. With 0 kg N, P fertilization resulted in 66–75% of total soybean N uptake in pods while that in stover decreased from 29 to 19%. Conversely, with 60 kg N, P fertilization caused 11% reduction in pods N and proportional increase in stover. Higher the N in stover, higher was the N carryover in litter fall and roots to subsequent cereal, although all above ground biomass was removed from the field in line with current farmer practice. Soil N mining by soybean was lowered by application of P at N0 while it increased with P at N60. Maize yield response to P fertilization was Yield0 = 1496 + 8.14P − 0.0758P2, R2 = 0.76 and Yield60 = 1791.7 − 14.79P + 0.1727P2, R2 = 0.93. Maize following soybean yielded 4–28% higher than the yield from bush fallow but 19–32% lower than the maize supplied with 60 kg N ha−1. Of the N estimated to have been retained in the field only 10% was recovered in the maize and remaining was lost to leaching, carried away by wind and animal grazing. Soil N monitored during non-cropped and cropped periods showed greater nutrient concentrations in the soybean fallow plots than in the bush fallow plots, which declined rapidly with increasing rainfall. Overall results shows that maize following soybean was productive, soil nutrient conserving and nutrient efficient than the maize grown on the bush fallow plots. Economic analysis of the two production systems showed that gross returns from soybean-maize rotation were $275–617 higher than the maize-maize rotation with no N inputs at all levels of P. The gross returns were comparable to the maize-maize rotation with 60-kg N ha-1 from soybean fallow plots with 60 kg N and at least 30-kg P ha-1. Farmer adoption and profitability may be further enhanced with strategies that improve nutrient recovery in subsequent maize and retain maximum stover as litter fall in the field

Geographic variation in growing season rainfall

Reports of changes in the seasonal and annual rainfall in Nigeria suggests that a more detailed analyses of the geographic extent of these changes and of their impact on agriculture could be of value. Variation in the growing season (April to September) rainfall from stations across Nigeria was analysed over the 30-yr period, 1960–90. Regression analyses were used to examine long-term trends. Principal component and cluster analyses were used to group stations with similar trends in standardised seasonal rainfall. Mean accumulated standardised seasonal rainfall were used to examine short- and medium-term trends for each of the groups identified. Significant (P ≤ 0.05) decreases in rainy season rainfall were found at 8 stations mostly in the Guinea and arid/semi-arid savannas of northern Nigeria, whereas no station showed significant increases. Examination of the monthly (April through September) rainfall showed that only three – Kano, Sokoto and Potiskum in the arid/semi-arid savanna – of the twenty-three stations used in the analysis had declining rainfall trends for each of the months April to September and subsequently declining seasonal rainfall trends. However, 12 to 15 stations had consistently declining rainfall trends in atleast some but not all the growing season months. However, a similar pattern was not the case in terms of increasing rainfall trends, where only one to three stations had consistently increasing rainfall trends in some but not all of the months from April to September. Stations that showed increasing rainfall trends were in the southern parts of Nigeria. Six groups with similar patterns in standardised seasonal rainfall were identified by Principal Component and Cluster analyses. For most of the groups, the period from 1967 to 1973 was that of consistently below average seasonal rainfall. However, the timing and extent of the decline varied with location. Common to stations in four of the six groups was a negative trend in seasonal rainfall for the period considered. The geographic variation in seasonal rainfall trends has tremendous agricultural significance since there are indications that the reliability of the season is decreasing from the humid forest zone with positive seasonal trends to the arid/semi-arid savanna with significant negative seasonal trends

Stratification and synthesis of crop–livestock production systems using GIS

Population increases, land-use changes and marketing opportunities are important factors affecting crop-livestock integra- tion particularly with respect to their effect on soil fertility and feed supply for ruminant livestock. As the human population density rises, crop farmers and grazers are finding it profitable to establish contracts for paddocking, and they are reaching agreement on equitable ways to make use of crop residues and take care of livestocks. As the processes of intensification proceed, mixed crop-livestock systems are evolving as the viable and dominant farming system, allowing smallholder farmers to capitalize on the complementarity between crops and livestock. Strategies directed to raise the productivity of specific crop-livestock systems need to consider the stage of development of the target area in relation to intensification and the nature of crop-livestock interactions. Information related to crop and livestock systems in West Africa is currently available from various sources e.g., household surveys, aerial surveys, rural appraisal, experimental etc., and held by different agencies. The approach used in this study shows how such data (biophysical and socioeconomic) can be integrated within a GIS environment and synthesized to identify the evolution of systems across environments and also to identify constraints and potential of the systems. Potential for integrated crop-livestock systems remains untapped and/or knowledge of its existence is unknown for large parts of Nigeria. Using data from 36 case studies and georeferenced data on cropping intensities and livestock population for the entire country, it was possible to predict emerging crop-livestock systems using GIS. Indeed, depending on availability of data, it is now possible to extend a similar approach in other African countries. The potential contribution of this technology is largely unknown in West and Central Africa, where few operational programs use them. Major technological innovations and appropriate government policies have potential to shift the balance in regional developments, if targeted carefully at areas where the right conditions exist. Further research could then target specific areas thus ensuring efficient allocation of resources while policy makers can achieve development goals by directing policies and resources to domains that have the greatest potentia

Longterm assessment of nitrogen and variety technologies on attainable maize yields in Nigeria using CERESmaize

Maize simulation models are proposed as tools for assessment of response to nitrogen (N) fertilizer and varieties in order to explore potential target zones for improved maize varieties. The CERES-maize model in the Decision Support System for Agrotechnology Transfer version 2.1 was tested using international testing nurseries at Ibadan, Mokwa, and Kaduna situated, respectively, in the derived savanna, southern guinea savanna, and northern guinea savanna zones in Nigeria during 1992–95. Historical weather data spanning 20 years were used at the target production environments to generate probabilistic estimates of maize yields; nitrogen use efficiency (NUE) associated with fertilizer and variety technologies. Analysis shows with high probability that, under rainfed conditions and N fertilizer input, the 90–110 day varieties (MDV) would yield better than 120–150 day varieties (LDV) at Mokwa and Ibadan, with superior NUE. The risk of crop failure with no N input was, however, substantial. Although response to N varied dramatically from year to year in association with the rainfall, there appears to be no advantage in adjusting N-input strategy for a variety. NUE was predicted to be best at the 60 kg N/ha input strategy, indicating potentials of further yield increase if methods of enhancing NUE at the higher N input levels could be further investigated. The NUE was found to be always lowest at Ibadan, in the derived savanna transition zone where rainfall and cloud cover were higher

Simulations of growth, development and yield of maize in the transition zone of Nigeria

The IBSNAT (Internal Benchmark Sites Network for Agrotechnology Transfer) CERES-Maize model, which stimulates a sole crop of maize, was tested during the 1990 and 1991 growing seasons at Ibadan in southwestern Nigeria. The maize model is designed to simulate plant physiological processes (nutrient and water uptake, transpiration, photosynthesis, organogenesis and biomass partitioning), and predict growth, development and yield in daily time steps in a manner similar to the processes as they are thought to occur in the real plant. An adequately tested and validated crop model with known genetic constants for varieties could be a time and money saving tool, useful for studying response of varieties in constrasting environments and management practices. Information on phenology, leafweight stem weight, above ground biomass, grain yield and leaf area index was collected approximately every 10 days. Daily weather data were collected using an automatic station located within the field. Genetic constants, i.e. growing degree days (base 8°C) from seedling emergence to the end of juvenile phase (P1), degree days (base 8°C) from silking to maturity (P5) potential number of grains per plant (G2) and potential grain growth rate during the linear filling stage (G3), were estimated using observed silking and maturity dates, grains per plant and weight per grain at harvest for each replication, using 1990 data. P1 and P5 were estimated to be 280 and 680 degree days across all replications; G2 was 647, 654 and 612 with a mean of 637·66 grains per plant; similarly, G3 was 9·2, 9·13 and 8·06 with a mean of 8·79 mg/day. The mean values of genetic constants were used for simulation of 1990 and 1991 growing seasons. No other adjustments were made in the model. Simulation of grain yield, weight per grain, grains per m2 (for 1991), leaf area index, stover weight and above ground biomass (for both 1990 and 1991) were predicted within 10% of the field observed data