Effects of the application of microbiologically activated bio-based fertilizers derived from manure on tomato plants and their rhizospheric communities.
Bio-based fertilizers (BBF) recovered from animal manure are promising products to optimise resources recovery and effectively generate agricultural products. However, their soil application may be detrimental to soil fertility and it is therefore of upmost importance to enrich BBFs with microbial consortia that improve physical, chemical and biological soil fertility. Three specific microbial consortia were developed according to the characteristics of three different BBFs produced from manure (i.e. bio-dried solid fraction, solid fraction of digestate and biochar) to enhance plant growth, soil organic matter degradation, nitrogen fixation and phosphorus use efficiency. Both BBFs and soil where chemically characterized and a greenhouse pot experiment was carried out with tomato plants (Solanum lycopersicum variety Minuet) grown with the amended BBFs applied either as N-organic fertilizers or as organic amendment. An array of qPCR analyses was carried out to quantify each microorganism within the three consortia across treatments and over time. Additionally, an amplicon (16S and ITS) next generation sequencing analysis was used to characterise the development of each rhizospheric communities. Fresh and dry plant weight from both microbiologically activated and non-activated treatments showed values similar to the untreated control and lower than the chemical fertilization control, whereas biochar showed the highest plant weight for both treatments. When considering fresh and dry tomato weight, all activated BBFs showed a higher tomato weight than the non-activated treatments and similar or higher than chemical fertilization. No particular patterns were seen concerning tomatoes quality (e.g. sugar-acid ratio, taste index, carotenoids and lycopene contents). Metagenomic analysis seems to point at Trichoderma as the main driver of the positive effect on tomato yields. In the context of circular economy, these activated BBF could be used as synthetic fertilisers alternatives reducing cost, environmental burden and increasing production.