In Tanzania, prices were relatively low in the south and coastal region and higher at the northwest. Our estimated prices can be adjusted when using them in computations for on-farm costs. The spatial data was handled with the “raster” package [38]. Discover a faster, simpler path to publishing in a high-quality journal. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Slope (USD kg-1) of the regression models between subsidized and non-subsidized prices. We did not use the data for Niger as the locations of the households were not provided, and there were only 13 households that reported a price for urea, which is our main focus in this paper. We had 159 cases from twelve countries from Africa Fertilizer data where we had subsidized and non-subsidized fertilizer prices from the same town. They both showed higher prices in the northwest, but they did not agree on prices in the south. Although we focus on the price for urea, we provide some comparison with the price for other fertilizers. Osmocote is a NPK coated fertilizer that releases nitrogen, phosphate and potassium and trace elements. Population and rural population density estimates were measured in persons per km2 [35]. Is the Subject Area "Fertilizers" applicable to this article? The outliers were not clustered in a specific region of the country. It is important to note that cross-validation results may be inflated for such regions because, on average, model skill should decrease with the distance from a location to locations with known prices (cf., [63]). That is why we developed Nutriology®, the science of growing. Last. However, in Ghana and Benin the prices were lower in the north, further away from the capitals and main ports. You have already submitted feedback. here. The tuneRF function was used to find the optimal number of variables available for splitting at each tree node (the ‘mtry’ parameter). For Rwanda, the spatial models performed worse than the Null model and the range in the relative prices was very low (0.99–1), so we assume no (systematic) variation in urea prices in these countries; and for that reason we did not include maps for Rwanda. The slopes (that is, how much the price of NPK/DAP/CAN changes for a one dollar increase in the urea price) were 1.07 USD kg-1 for NPK; 1.16 USD kg-1 for DAP; and 0.95 USD kg-1 for CAN (Fig 3). Yes It is taken into consideration of four types fertilizers in South Africa, including LAN, MAP, urea and MOP. Funding acquisition, A few studies have utilized “local” prices calculated as sub-national mean prices (e.g. Crop yields in Sub-Saharan Africa (SSA) are generally very low [1, 2]. In this case, transportation cost (USD kg-1 of purchased fertilizer) by transportation type range between 0.01 to 0.05 USD kg- (Table 4). 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. For Ethiopia, 37% of the outliers were associated with fertilizer purchases in quantities of 4 kg or less and very low prices (< 0.1 USD kg-1). https://doi.org/10.1371/journal.pone.0227764.t003. 1.37. Except for Senegal, these countries are neighbors and use a common currency (West African CFA franc). For Ethiopia, Mali, and Malawi, prices were reported as the total amount paid for a quantity of fertilizer purchased expressed in the national currency. The allocation of subsidized fertilizer, and the degree to which this leak into the non-subsidized market could also influence prices [51]. We thank Drs. On average travel time to markets over 50,000 was 3.98 hours and the slope between transportation cost and travel time was 0.43 USD. In Mozambique prices were lowest near the border with Zambia. For country-level models the data source was Africa Fertilizer, except where indicated otherwise. The countries with the highest urea price in West Africa were Burkina Faso, Togo, Senegal, Mali, and Niger. For each country and region (West and East Africa), Random Forest Regression and Thin Spline Plate algorithms were used to fit models. We had most observations on non-subsidized prices for Ethiopia (2045), Nigeria (1135), Malawi (1142), Tanzania (515), and Mali (386) due to the large sample of fertilizer users in the LSMS data for these countries (in addition to the Africa Fertilizer data available for two of these countries). The PPP conversion factor represents how much of a country’s currency (expressed in USD using the international exchange rate) is required to buy the same amounts of goods and services in the domestic market as one USD would buy in the United States. From 2010 to 2018, countries in which Africa Fertilizer reported subsidized prices were: Benin, Burkina Faso, Burundi, Ghana, Malawi, Mali, Nigeria, Rwanda, Senegal, Tanzania, Togo, and Zambia (Table 2). We used an ensemble model of Random Forest Regression and Thin Plate Spline methods. For the Africa Fertilizer data set, we fitted: (a) a liner regression model with no intercept between the prices for urea and the other fertilizer types, for locations where both the urea price and that of another type were reported; (b) the same linear regression models for each country separately; and (c) a liner regression model with no intercept between subsidized and non-subsidized urea prices, for each country separately. 5%. CSV XML EXCEL. 1.02. ER: Relative mean square error, calculated as: 1-(EI / E0). The top supplying country or region is South Africa, which supply 100% of npk fertilizer respectively. We combined the Random Forest and TPS models into a single ensemble model using the weighted average of the inverse Root Mean Square Error (RMSE) of each model. The main goal of this paper was to describe price variation within and between countries and to use spatial interpolation models to predict local prices of urea, a commonly used source of inorganic nitrogen. For the regional models, the correlation between observed and predicted prices was 0.59 for East Africa and 0.54 West Africa and the models performed 21% and 16% better than the Null model (Table 3). Vegetables, Flowers, Fruit, Base Ground and Top Dressing. Formal analysis, A few studies have utilized price variation obtained from averaging price survey data over arbitrary sub-national boundaries, such as districts or regions (e.g. E0: Mean square error of the Null model. However, it is worth noting that these price data are only collected in towns and may not reflect the likely higher prices in more isolated rural areas. For this study, we focus on urea price because it is the product with most observations across all the countries studied and because it is an unambiguous product (unlike, for example, fertilizers labeled as “NPK” which may vary widely in composition percentages). https://doi.org/10.1371/journal.pone.0227764.t002. While we were able to remove outliers, we had no way of correcting error for prices that were within a reasonable range of values. Non-Subsidized market could also influence prices [ 51 ], 2 ] is Subject... Distance to port: travel time was 0.43 USD conversions to provide you with,. 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