Phosphorus (P) is an essential nutrient for crop growth and production. In Sub-Saharan
Africa (SSA), deficit of soil P is one of the most serious constraints to crop yield. This shortfall has
resulted from the high P fixation capacities of highly weathered acidic soils in SSA, spreading
throughout a range of agricultural lands, from upland to lowland fields. To cope with the P deficiency,
however, resource-poor farmers in SSA cannot apply commercial water-soluble P fertilizers because of
their very limited accessibility and affordability.
As its deposits are found in several places in SSA, indigenous phosphate rock (PR) should be
recognized as a cheaper alternative source of P for local agricultural production. Hence, it is important
to develop appropriate methods for effective utilization of local PRs after knowing their chemical and
physical properties. PRs mined in SSA, with lower water-solubility, are generally considered to have
less effectiveness when they are directly applied onto the fields. Even so, it is worth to evaluate the
effectiveness of PRs on agricultural systems which are differed in crops and environmental (soil and
climate) conditions in SSA.
The JIRCAS Team, collaborating with colleagues in West Africa, has shown a positive effect
of the directly-applied PR from Burkina Faso (BPR) on the growth and yield of lowland rice in
ecologies of Equatorial (Ghana) and Savanna Zones (Ghana and Burkina Faso). BPR could also be
utilized as a delayed-release P fertilizer as it demonstrated a significant residual effect in the same
ecologies.
For the sake of increase in solubility of BPR, several processing technologies have been
examined in consideration of farmers and/or community-based feasibility, e.g., low-temperature
calcination during charring and biological acidulation during composting.