Culture-Independent Characterization of Bacterial and Fungal Communities Dynamics in Soil, Root and the Treatments aqueous phases.
Biochar and bokashi liquid digestate (Bok-L) valorize agricultural waste streams and can underpin circular, low-input citrus nurseries. We tested almond-shell biochar (10% v/v) and citrus-waste Bok-L (0.5% v/v), alone or with a mature-root microbiome transplant, across two 21-week greenhouse trials with Carrizo and C-35 rootstocks. Biochar + Bok-L (T7) and its primed-microbiome variant (T8) enriched soil and root microbiomes, doubling aerobic heterotrophic bacteria and lifting fungal richness by 28% over the control. Spearman correlations showed that the abundance of nutrient-cycling Actinomycetales positively predicted total organic carbon (rho = 0.68) and seedling biomass (rho = 0.65, p < 0.01), directly linking microbial shifts to carbon retention and growth. Companion carbon-dynamics analyses confirmed these treatments sequestered 46% more soil organic carbon and cut water-extractable nitrogen losses by 32%. Biochar + Bok-L increased Carrizo germination by 17% and shoot dry mass by 20%, whereas priming the microbiome sometimes dampened germination, underscoring the need to tailor amendment timing. Sequencing revealed enrichment of Pseudomonas, Kitasatospora, and Sebacina, taxa tied to nutrient cycling and pathogen suppression, and alpha-diversity metrics confirmed synergistic effects of the combined amendments. Collectively, waste-derived biochar and Bok-L orchestrate a more diverse, functionally beneficial rhizosphere, improve carbon and nitrogen economics, and accelerate early citrus growth, offering a scalable, climate-smart strategy for resilient nursery production.