ИСТИНА

Phosphorus fertilizers, a lifeblood of modern agriculture, are exclusively made from rock phosphate—a finite non-renewable unevenly distributed resource. Current processes of phosphorus usage are far from sustainable (>80% of mined phosphorus ends up in waste). The waste phosphorus is carried to water bodies with runoff waters causing harmful algae bloom and eutrophication. At the same time microalgae are evolved to accumulate a lot more phosphorus than needed for their cell division, mainly in form of polyphosphate. This capability of microalgae is termed “luxury uptake”. Our recent tests showed that the phosphorus-enriched biomass of microalgae can substitute conventional phosphorus fertilizer, even without treatment of the biomass and tilling it into the soil. An added value of the microalgae-based phosphorus biofertilizer is slow release of phosphorus upon decomposition in the soil preventing its washout with runoff water and improving the soil structure. We explore the kinetics of inorganic luxury phosphorus uptake by microalgal cultures as a function of their nutrition prehistory and relationships between the luxury uptake parameters, accumulation and expenditure of intracellular polyphosphate in several chlorophyte strains in lab- and pilot-scale cultures. An optimized process of microalgal culture conditioning for production of phosphorus biofertilizer is proposed. Funding by the Russian Ministry of Science and Education (project 14.616.21.0080) is gratefully acknowledged.