Polysaccharide-coated apatite formulations: Enhanced plant P-uptake and reduced environmental migration

Phosphorus (P) is a critical plant macronutrient, however, P solubility from soil P-minerals, such as apatite, is low. Commercial P fertilizers, while providing immediate availability, are prone to P-soil fixation and rapid loss via migration, reducing P-plant availability and posing environmental risk, respectively. We designed and characterized polysaccharide- apatite formulations (Ap@Muci), hypothesizing Ap@Muci induces soil microbial activity, thereby enhancing P solubility and plant availability. Soil microbial activity, monitored via CO₂ emissions, was higher in Ap@Muci treated soils, in comparison to control, apatite or mucilage treated soils. Enhanced P solubilization from Ap@Muci was obtained upon incubation in soil solution, compared to a sterile solution, and supported by microbial colonization on Ap@Muci particles. In a tomato bioassay Ap@Muci treated soils sustained P concentrations (Olsen test) overtime, while P concentrations decreased in the control and apatite treatments, resulting in significantly higher P-uptake by the plants treated with Ap@Muci. In a wheat bioassay, the biomass of the Ap@Muci treatment was higher, even than the commercial triple-superphosphate (TSP) treatment. Furthermore, Ap@Muci treated soils, significantly reduced P migration relative to TSP. Finally, Ap@Muci stimulated rhizosphere microbial activity, enhanced P solubility and plant uptake, while reducing its migration, providing a foundation for sustainable fertilization development.