Spatial variation in fertilizer prices in Sub-Saharan Africa.

Low crop yields in Sub-Saharan Africa are associated with low fertilizer use. To better understand patterns of, and opportunities for, fertilizer use, location specific fertilizer price data may be relevant. We compiled local market price data for urea fertilizer, a source of inorganic nitrogen, in 1729 locations in eighteen countries in two regions (West and East Africa) from 2010-2018 to understand patterns in the spatial variation in fertilizer prices. The average national price was lowest in Ghana (0.80 USD kg-1), Kenya (0.97 USD kg-1), and Nigeria (0.99 USD kg-1). Urea was most expensive in three landlocked countries (Burundi: 1.51, Uganda: 1.49, and Burkina Faso: 1.49 USD kg-1). Our study uncovers considerable spatial variation in fertilizer prices within African countries. We show that in many countries this variation can be predicted for unsampled locations by fitting models of prices as a function of longitude, latitude, and additional predictor variables that capture aspects of market access, demand and environmental conditions. Predicted within-country urea price variation (as a fraction of the median price) was particularly high in Kenya (0.77-1.12), Nigeria (0.83-1.34), Senegal (0.73-1.40), Tanzania (0.90-1.29) and Uganda (0.93-1.30), but much lower in Burkina Faso (0.96-1.04), Burundi (0.95-1.05), and Togo (0.94-1.05). The correlation coefficient of the country level models was between 0.17 to 0.83 (mean 0.52) and the RMSE varies from 0.005 to 0.188 (mean 0.095). In 10 countries, predictions were at least 25% better than a null-model that assumes no spatial variation. Our work indicates new opportunities for incorporating spatial variation in prices into efforts to understand the profitability of agricultural technologies across rural areas in Sub-Saharan Africa.

Medio agar urea de Christensen modificado / Christensens agar urea media modified

Debido a la falta de abastecimiento de urea para la confección del medio de cultivo agar urea de Christensen y prolongar la existencia de la urea que se encontraba en el almacén, con el objetivo de detrminar si era factible reducir la concentración de urea en dicho medio de cultivo para lo cual se confeccionó el medio de cultyivo con 50 mililitros de la solución estéril de urea al 40 por ciento (lo normado) y diferentes lotes con 40, 30, 20, 15, 10, 5 y 2,5 mililitros de la solución estéril de urea al 40 por ciento para determinar la concentración mínima óptima de urea dentro del medio de cultivo capaz de brindarnos resultados confiables. Con la aplicación de esta racionalización se ha logrado un significativo ahorro del reactivo urea, además posee efecto económico, social y técnico positivo(AU)