Valorization of the Natural Phosphate of Tilemsi (PNT) for the Development of the Agricultural Productions in Mali

Abstract

In Mali, the deficiency of agricultural soils in phosphorus is one of the limiting factors in crop production. They respond well to phosphorus fertilization, but the high price of imported chemical fertilizers limits their use by the producers. However, Mali has large deposits of natural phosphate in the Tilemsi Valley (PNT) in northern Mali. Faced with this situation, the Government encouraged the use of local fertilizing resources including the PNT. Despite the satisfactory results of several years of research and popularization, the PNT was poorly adopted by the producers because of its powdery appearance, which made it difficult to apply in the field, its low solubility in the soil, which made its effect noticeable on crops in the second year of its application and its brown color reminiscent of that of earth made the producers believe that it had no fertilizing value. Faced with these problems relating to the physical appearance and the low solubility of the PNT, the laboratory work of GREAT QUEST Fertilizer SA resulted in the development of simple formulations based on enriched granular PNT 27% P 2 O 5 (average content) and 35% P 2 O 5 (high content) for direct application and NPK complex formulations based on granulated enriched PNT 35% P 2 O 5 mixed mainly with urea, potassium, and sometimes with other nutriments like sulfur and boron (NPK 15-15-15; NPKSB 14-18-18-6-2) with a solubility in citric acid of 71.1%. The results of four years of experimentation of enriched granular PNT in the research stations and in the peasant environment showed a greater or equal effect than the other popular fertilizers. This project aims to improve phosphate nutrition and crop production by using granulated formulations of enriched PNT 27% P 2 O 5 and 35% P 2 O 5 .