(P23-017-25) Environmentally Sustainable Technologies for Bio-Char Production From Pistachios Byproducts and Microbial Bioactivation for Soil Improvement

Objectives: The present study aims to design a sustainable biotechnological process that uses pistachio by-products (shells and husks) as substrates to produce biochar and bio-activated biochar, which will then be employed as growth factors in agriculture.

Methods: Biochar from pistachio shells and husks, produced by thermochemical gasification, was analyzed in terms of chemical-physical parameters, inorganic and organic parameters. Bioactivation was performed by two bacterial strains, Streptomyces nigra and Bacillus subtilis. An optimization procedure using full factorial design (FFD) aimed to test biochar as carrier for plant growth-promoting rhizobacteria (PGPR) by the determination of cell viability over time.

Results: Most of the biochar particles had a size between 500 mm (30.8% and 22.5%) and 2.0 (29.9% and 48.5%) mm, with a lower proportion (16.7% and 20.9%) >5.0 mm in the biochar from husks and shells, respectively. Except for calcium, metals were detected in higher concentrations in the biochar from husks compared with shells. Biochar from pistachio husks showed higher (0.5 log) immobilization compared with shells for both strains. Incubation time did not significantly affect the bioactivation process (p-value > 0.05).

Conclusions: Pistachio biochar bioactivated with Streptomyces nigra and Bacillus subtilis may serve as a sustainable biofertilizer to boost soil fertility and crop production. This will result in a reduction of the use of agrochemical compounds in agriculture, together with an integrative approach to valorize pistachio by-products within a circular economy goal.

Funding Sources: The work has been funded by PNRR, MISSIONE 4 “Istruzione e ricerca” – COMPONENTE 2 “Dalla ricerca all’impresa” – LINEA DI INVESTIMENTO 1.4 “POTENZIAMENTO STRUTTURE DI RICERCA E CREAZIONE DI "CAMPIONI NAZIONALI DI R&S" SU ALCUNE KEY ENABLING TECHNOLOGIES” – Programma di Ricerca e Innovazione “AGRITECH – NUOVI MODELLI DI ECONOMIA CIRCOLARE IN AGRICOLTURA ATTRAVERSO LA VALORIZZAZIONE E IL RICICLO DEI RIFIUTI”, CN00000022, SPOKE 8, CUP G43C22003330005, finanziato dall’Unione Europea – NextGenerationEU