## 5 Recycling Agricultural Biomass for Sustainable Soil Microbiome Management
### Application of On-Farm Green Compost and Bio-Organic Fertilizer
(2020) [299] showed the potential role of the bacterial genera _Nocardiopsis_ and _Pseudomonas_ in disease suppression, and _Falrobacterium_ and _Streptomyces_ in plant biostimulation. [PERSON] et al. (2020) [347] studied four different waste-based composts by omics procedures, targeting the 16S rRNA and 18S rRNA genes by real-time PCR amplification and the 26S gene by amplicon-based sequencing. They concluded that the composts possessed suppressive property against Phytophthora diseases (root, fruit, foliar and crown rot) by _P. capsici_ in summer squash. Total abundance of the bacterial and fungal communities was found to be higher when compared to the literature data, thus confirming that compostis good inoculum for increasing the suppressive property of conducive soils. [PERSON] et al. (2020) [298] reviewed the opportunities to increasingly harness compost microbiomes for plant protection through an integrated approach that combined the power of the functional assays to isolate BCAs and PGPR by amplicon and shotgun sequencing to achieve a better understanding of the compost complex system for identifying what taxa were enriched in suppressive composts. Combined application of OAs supplemented with BCAs, commonly named bio-organic fertilizers (or compost-fortified), were proven to enhance plant resistance against pathogens that is partly due to the impact of the resident soil microbiome on the structure and function of the pathogen-infected plant. Although this topic has been extensively studied since the 2000s and then reviewed by [PERSON] and [PERSON], (2015) [60], nonetheless, it remains still unclear whether such improvements were driven by the specific action of exogenous bio-inoculants and resident microbial population in the bio-organic fertilizer or by the physicochemical properties of the substrate; [PERSON] et al. (2020) [348] investigated the compost spent espresso coffee ground property as a high-value organic fertilizer for soil amendment if fortified with selected fungal inoculants in suppressing damping-off of stress by _S. sclerotium_ and _P. nicotiana_ in greenhouse potting soil. These authors explained the suppressive action through multiple antagonistic effects related to the bioactivity of antimicrobial compounds, toxic volatile and non-volatile metabolites produced by _Triboderma atroviride_, _Triboderma etrinoviride_ and _Aspergillus_ spp. [PERSON] et al. (2020) [349] conducted an experimental trial tracking the fusarium wilt disease of banana by _F. oxysporum_ f. sp. _cubense_ and the changes in microbial communities over three growth seasons in response to the following treatments: (a) bio-organic fertilizer supplemented with _Bacillus amyloliquefaciens_ W19, (b) organic fertilizer alone, (c) sterilized organic fertilizer, and (d) sterilized organic fertilizer supplemented with the strain W19. They concluded that suppression was linked to the impact on the resident soil microbial communities, specifically leading to the increase in specific strains of _Pseudomonas_ spp. They further observed correlation between the _Bacillus_ spp. amendment and the indigenous _Pseudomonas_ spp. that might underlie pathogen suppression. These studies revealed that specific bacterial taxa can synergistically increase the biofilm formation around roots, acting as a plant-beneficial consortium against the pathogen. Table 1 summarizes the most recent and promising green composts and bio-organic fertilizers obtained through a circular economy system for increasing soil suppression. Such biomass was studied in the last five years for its suppressive effects on soil-borne pathogens and diseases in relation to characterization of its microbiomes by high-throughput amplicon sequencing. Table 2 overviews the most promising combined agricultural practices supported by the omics-based technologies for increasing soil suppression.