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Background and Aims: Re-vegetation of contaminated and disturbed landscapes can reduce the transport of toxic elements while improving soil fertility. This study evaluated whether the planting of a perennial grass with diazotrophic microbial endophytes and municipal waste compost—alone and in combination—improved phytostabilization of potentially toxic trace elements in dolomite-amended tailings from a historically mined polymetallic mineral deposit.Methods We grew Bouteloua curtipendula seedlings in tailings with hazardous concentrations of As, Cd, Pb, Mn, and Zn. We evaluated how plant growth, organic matter accumulation, and minor and trace element mobilization responded to microbial endophyte and organic amendments.Results Although most of the added endophytes were not uniquely identified, the best plant growth and fertility outcomes were achieved with a combination of amendments: dolomite to reduce acidity, a compost topdressing to accumulate nitrogen in the tailings, and a mixed consortium endophyte seed coating to synergistically increase organic carbon and grass biomass yields. Combining amendments also improved phytostabilization: compost reduced the shoot forage toxicity of B. curtipendula seedlings without reducing phytostabilized contaminant yields in the rhizosphere, while endophyte inoculated grass marginally reduced total and water-extractable concentrations of toxic trace elements through enhanced mobilization.Conclusion The most effective means of reclaiming these acidic, polymetallic tailings is with a simultaneous dolomite, compost, and endophyte seed treatment.

1. Microbial necromass is a large, dynamic and persistent component of soil organic carbon, the dominant terrestrial carbon pool. Quantification of necromass carbon stocks and its susceptibility to global change is becoming standard practice in soil carbon research. However, the typical proxies used for necromass carbon do not reveal the dynamic nature of necromass carbon flows and transformations within soil that ultimately determine necromass persistence. In this review, we define and deconstruct four stages of the necromass continuum: production, recycling, stabilization and destabilization. 2. Current understanding of necromass dynamics is described for each continuum stage. We highlight recent advances, methodological limitations and knowledge gaps which need to be addressed to determine necromass pool sizes and transformations. We discuss the dominant controls on necromass process rates and aspects of soil microscale structure including biofilms and food web interactions. The relative importance of each stage of the continuum is then compared in contrasting ecosystems and for climate change drivers. 3. From the perspective of the continuum, we draw three conclusions to inform future research. First, controls on necromass persistence are more clearly defined when viewed through the lens of the continuum; second, destabilization is the least understood stage of the continuum with recycling also poorly evidenced outside of a few ecosystems; and third, the response of necromass process rates to climate change is unresolved for most continuum stages and ecosystems. 4. Future mechanistic research focused on the role of biotic and abiotic soil microscale structure in determining necromass process rates and the relative importance of organo–mineral and organo–organo interactions can inform necromass persistence in different climate change scenarios. Our review demonstrates that deconstructing the necromass continuum is key to predicting the vulnerability and persistence of necromass carbon in a changing world.