In West Africa, including Burkina Faso, crop yields are limited by a number of factors, including harsh weather conditions and low soil fertility, and many countries are experiencing chronic food shortages. Whereas in developed countries, excessive application of fertilizers causes various problems such as pollution of the hydrosphere and greenhouse gas emissions, in many African countries, low productivity is the result of low fertilizer application, which in turn leads to the expansion of cultivated land.

The fact that the price of 100 kg of imported NPK [nitrogen (N), phosphorus (P), and potassium (K)] fertilizer distributed in Burkina Faso is equivalent to 20 days of labor wages for an average farmer, and is very expensive compared to other regions, is another factor that prevents increased fertilizer application. In particular, there is a serious shortage of phosphorus, which needs to be replenished through fertilization.

On the other hand, Burkina Faso has more than 100 million tons of phosphorus resources, but most of it is unused because it is classified as low-grade due to its high impurity content and low reactivity. Therefore, the SATREPS Burkina Faso project, which started in 2017, has been promoting the development of domestically produced fertilizers in Burkina Faso by applying two methods to increase the solubility of low-grade phosphate rock: the calcination method, in which the rocks are calcined with alkali salts at a high temperature of 900°C or higher, and the partial acidification method, in which the rocks are reacted with sulfuric acid. 

In two papers published in 2021, the effectiveness of calcined and partially acidified phosphate fertilizers was verified in actual farmer fields for rice cultivation. The paper Site-specific responses of lowland rice to acidulated and calcined phosphate rock fertilizers in the Center-West region of Burkina Faso published in PLOS ONE showed that both calcined and partially acidified phosphorus fertilizers are effective, and that the effectiveness of fertilizer application depends on soil properties and water environment. Based on these results, the paper Optimal P fertilization using low-grade phosphate rock-derived fertilizer for rice cultivation under different ground-water conditions in the Central Plateau of Burkina Faso, published in Soil Science and Plant Nutrition, focused the analysis on the water environment. As a result, it was found that the optimal type and amount of phosphorus fertilizer depends on the distance from the lowland (ground-water level), and that sufficient profit can be obtained when the optimum management is applied.

These results will contribute to the spread of domestic phosphorus fertilizers and improvement of fertilizer application techniques in Burkina Faso. The dissemination of domestically produced fertilizers in African countries that have been dependent on imported fertilizers and the shift to local production for local consumption will contribute to stable food self-sufficiency throughout Africa.
 

References

Monrawee Fukuda, Dohan M. Soma, Shinya Iwasaki, Satoshi Nakamura, Takashi Kanda, Korodjouma Ouattara & Fujio Nagumo (2021). Site-specific responses of lowland rice to
acidulated and calcined phosphate rock fertilizers in the Center-West region of Burkina Faso. https://doi.org/10.1371/journal.pone.0250240

Shinya Iwasaki, Monrawee Fukuda, Kenta Ikazaki, Satoshi Nakamura, Korodjouma Ouattara & Fujio Nagumo (2021) Optimal P fertilization using low-grade phosphate rock-derived fertilizer for rice cultivation under different ground-water conditions in the Central Plateau of Burkina Faso. https://doi.org/10.1080/00380768.2021.1932584

Contributor: IWASAKI Shinya (Crop, Livestock and Environment Division)