Enhancing fertilizing properties of solid fraction of digestate by microbial bioactivation: In-field application effects on yield and quality of tomato plants

Bio-based fertilizers (BBFs) derived from animal manure hold great potential to optimize resource recovery and boost agricultural yields. BBFs fertilization potential may be however limited, so enriching BBFs with microbial consortia is necessary to enhance their effectiveness. This study evaluated the fertilization efficiency and effects of a BBF fertiliser, a digestate derived from a mix feed of energy crop and bovine waste, activated with a custom-made microbial consortium at field scale on tomato fruit yield and quality. Next-generation sequencing was further employed to analyse the permanence of each component of the microbial consortium across time. Results demonstrated that microbiological activation significantly improved the fertilization performance of the BBF. Tomato yields and quality parameters in the microbiologically activated BBF trial matched or exceeded those in the chemically fertilized trial. The consortium, mainly Trichoderma, Metarhizium, and Bacillus, markedly boosted nutrient absorption from the soil and improved the protein and nutrient content of the tomato fruits. At the field scale, biological activation has the potential to completely replace synthetic fertilizers, however, to further enhance lycopene and carotenoid yields, it is important to address the reduced sunlight exposure caused by increased leaf biomass and the growth of numerous weeds with microbial activation. To reach the widespread adoption of biologically activated BBFs and meet Sustainable Development Goals, future research should emphasize conducting more field studies and creating new BBF formulations developed with custom microbial consortia to address specific plant, soil, and environmental requirements.