Innovative phytomanagement systems by combining miscanthus and switchgrass with biostimulants to enhance microbial diversity and soil remediation

Establishing resource efficient non-food crops on contaminated land by implementing different crop management regimes is gaining attention as a strategy for a sustainable long-term management of polluted soils. Therefore, the current study aims to set-up a technology with enhanced phytoremediation capacity by combining perennial energy crops miscanthus and switchgrass with biostimulants to promote beneficial soil bacteria and fungi, evaluated through field trials on a metal polluted soil. The crops' growth was compared under two different biostimulants treatments and a control taking into account biomass yield, morphological parameters, soil physicochemical and biological properties. The findings demonstrate that biostimulants treatments compared with control positively influenced crop biometric traits and increased biomass yield up to 3 t ha(-) (+54 %) and 9 t ha(-1) (+35 %) for miscanthus and switchgrass, respectively in the second establishment year. Biostimulants treatment HAM (humic acid combined with mycorrhizae) performed best. This biostimulants treatment reduced the metal CaC(l)2-available fraction in both miscanthus and switchgrass plots, with the exceptions of Pb in switchgrass and Cu in miscanthus. This study clearly corroborated that both factors under study, i.e crop type and biostimulants applications have influenced the soil microbiome structure. Compared with the control group, biostimulants HAM treatment increased abundance of Bacillus by 44 % in miscanthus and Candidatus Solibacter by 200 % in switchgrass. In the case of fungi, the biostimulants HAM treatment promoted the relative abundance of Fusarium in the rhizospheres of both miscanthus and switchgrass. Collectively, the findings of this study suggest that selecting the right crop and biostimulants application can modulate the rhizosphere environment, consequently enhancing the effectiveness of phytomanagement technologies.