Mycorrhizal-Assisted Phytoremediation and Intercropping Strategies Improved the Health of Contaminated Soil in a Peri-Urban Area

Abstract

Soils of abandoned and vacant lands in the periphery of cities are frequently subjected to illegal dumping and can undergo degradation processes such as depletion of organic matter and nutrients, reduced biodiversity, and the presence of contaminants, which may exert an intense abiotic stress on biological communities. Mycorrhizal-assisted phytoremediation and intercropping strategies are highly suitable options for remediation of these sites. A two-year field experiment was conducted at a peri-urban site contaminated with petroleum hydrocarbons and polychlorinated biphenyls, to assess the effects of plant growth (spontaneous plant species, Medicago sativa, and Populus × canadensis, alone vs. intercropped) and inoculation of a commercial arbuscular mycorrhizal and ectomycorrhizal inoculum. Contaminant degradation, plant performance, and biodiversity, as well as a variety of microbial indicators of soil health (microbial biomass, activity, and diversity parameters) were determined. The rhizosphere bacterial and fungal microbiomes were assessed by measuring the structural diversity and composition via amplicon sequencing. Establishment of spontaneous vegetation led to greater plant and soil microbial diversity. Intercropping enhanced the activity of soil enzymes involved in nutrient cycling. The mycorrhizal treatment was a key contributor to the establishment of intercropping with poplar and alfalfa. Inoculated and poplar-alfalfa intercropped soils had a higher microbial abundance than soils colonized by spontaneous vegetation. Our study provided evidence of the potential of mycorrhizal-assisted phytoremediation and intercropping strategies to improve soil health in degraded peri-urban areas.

Changes in Lolium perenne L. rhizosphere microbiome during phytoremediation of Cd- and Hg-contaminated soils

“…In other studies with L. perenne, it has been found that its roots form arbuscular-type mycorrhizae (Leudo et al 2020), which, according to some authors, makes them unique model systems for the study of interactions between plants and microorganisms (Gómez-Sagasti et al 2021). In this study, it has been proven that mycorrhizae favor the presence of other microorganisms that help in the performance of metal uptake by the roots.…”

Distinct rhizosphere soil responses to nitrogen in relation to microbial biomass and community composition at initial flowering stages of alfalfa cultivars

“…In addition, Plants can directly alter the soil microbiome by secreting and releasing bioactive molecules and metabolites ( Pang et al, 2021 ). Root exudates may differ between plant species, different growth stages, and even between the same plant species ( Micallef et al, 2009 ; Li et al, 2013 ; Dietz et al, 2019 ), therefore, root exudates from the twelve alfalfa cultivars might have led to changes in soil physiochemical properties ( Zhang et al, 2020 ), and most likely contributed to the effects on soil microbial activity and biomass ( Gomez-Sagasti et al, 2021 ).…”

Integrative assessment of in situ combined bioremediation strategies applied to remediate soils spilled with sewage sludges

“…The abovementioned reductions were probably influenced by plant growth that improves rhizosphere interactions by releasing root exudates. These interactions help to create a suitable environment for microbial development, increasing rhizodegradation and microbial degradation processes (Reilley et al, 1996;Epelde et al, 2009;Stefanowicz et al, 2012;Nui et al, 2021;Gómez-Sagasti et al, 2021). Different authors (Park et al, 2011;Niu et al, 2021) have already reported that plants can influence metal uptake and/or immobilization through different interactions in the rhizosphere.…”