Impacts of Grinding and Acidification of Animal Bones with Coffee Wastewater on Plant Dry Matter Yield and Recovery of Phosphorus

Abstract

ABSTRACT In sub-Saharan Africa, soil fertility depletion and limited access to mineral phosphorus (P) fertilizers are considered among the main constraints of crop productivity. The goal of our work is to make P fertilizer from locally available materials, thus reducing the costs due to importation and transportation for smallholder-farmers with limited financial capacities. Cattle bones collected from slaughterhouses were ground to two fineness-level, acidified using coffee wastewater (pH ~4.3), and then compared to commercially available diammonium phosphate (DAP) in a pot experiment using Zea mays (maize) and Phaseolus vulgaris (common bean). Finely ground bones increased maize and common bean dry matter yield (DMY) and P uptake compared to coarsely ground bones, but a significant interaction between grinding and acidification also suggests that acidification with coffee wastewater increased availability of bone-based P, at least two-times more DMY and P uptake under acidified finely ground bones than for non-acidified treatments. In addition, acidified finely-ground bones produced maize and common bean DMY, P uptake and P recovery efficiency that were comparable to those of DAP. These results demonstrate the utility of acidified finely ground bones to enhance crop yields, potentially serving as an alternative P-rich resource to imported and expensive fertilizers that depend on nonrenewable resources.