Effect of the addition of PGPB to a valorized organic residue (biofertilizer) on the improvement of the nutritional composition and rhizospheric microbiota of alfalfa (Medicago sativa).

In recent years, the excessive utilization of agrochemicals and the overexploitation of agricultural land have resulted in amplified soil and aquifer pollution, along with the expansion of unproductive land areas. The valorization of waste and the adoption of biofertilizers, incorporating Plant Growth-Promoting Bacteria (PGPB), present a distinctive opportunity to contribute to the planet's sustainability. This study conducts a comparative analysis of irrigation regimes involving various chemical treatments (water, NPK fertilizer, valorized organic fertilizer ORGAON®PK, and sterilized organic fertilizer ORGAON®PK) supplemented with PGPB Bacillus pretiosus and Pseudomonas agronomica (biological treatment). The germination rate, biomass production, and nutritional quality of the forage plant Medicago sativa (alfalfa) were assessed after three weeks of growth. Statistical analyses (principal component analysis and ANOVA) showcase the ability of the added PGPB to synergize with their respective chemical treatment matrices. The biological treatment of PGPB delivered in different chemical matrices fosters germination, plant development, and enhances the nutritional composition of the plants. Additionally, an improvement in soil quality is observed in the edaphic microbial community, quantified by an increase in metabolic diversity and a reduction in the minimum inhibitory concentrations of all studied antibiotics. From a genotypic perspective, a reduction in the taxonomic diversity of the microbiota is noted, suggesting the temporary survival of the added strains in the rhizosphere of Medicago sativa. In conclusion, the use of organic fertilizers (biofertilizers) emerges as an ecologically and economically viable alternative for agricultural production, replacing traditional chemical fertilizers that are directly associated with soil impoverishment and fertility loss. • Waste valorization as biofertilizer present an opportunity to sustainable production. • PGPBs play a crucial role in agrosystem modern production. • ORGAONPK, B. pretiosus and P. agronomica improve M. sativa development and quality. • Metagenomics reveals the survival of B. pretiosus and P. agronomica in rhizosphere. • The strains reduces the antibiotic resistance profile of the rhizospheric community.