Microbial community adaptation in biosolid-based engineered soils

Abstract

Land degradation affects approximately a quarter of the Earth´s surface, driving interest in engineered soils, known as Technosols, as tools for ecosystem restoration, carbon sequestration, and biomass production. Tech- nosols are constructed from technogenic materials combined with stabilized organic waste, yet their capacity to develop soil-like microbial communities and functions under field conditions remains poorly understood. In this field study, we assessed microbial activity and community structure in Technosols formulated by mixing equal parts of Horizons A, C, and Bt with Class B biosolids (70:30, v/v). Natural topsoil (A horizon) served as a reference for native soil microbial communities. The experiment was established in randomized blocks planted with polyphitic pastures. Technosols contained substantially higher organic matter (8.4% vs 4.6%), extractable phosphorus (349 vs 15 mg. kg− 1), and total nitrogen (0.35% vs 0.16%) compared to A horizon, resulting in significantly greater pasture biomass yield, with uncompacted Technosols producing the highest yield of 12.65 t ha− 1 vs 8.71 t ha− 1 in A horizon. After 7 months, community-level physiological profiles (CLPP) and soil enzymatic activity of Technosols mirrored those observed in natural topsoil, indicating rapid functional convergence of microbial communities. In contrast, principal coordinate analysis of bacterial and fungal amplicon sequencing data revealed persistent differences in bacterial and fungal community composition among soil types and between early and late sampling. This suggests that biosolid-based Technosols acquire soil-like functions primarily through shifts in microbial activity that precede major changes in community composi- tion, underscoring the capacity of microorganisms to adjust their functional strategies in engineered soils.