Soil physical potential of constructed Technosols from Iron mining tailings and construction and demolition waste

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The unsustainable disposal of solid waste, such as mine tailings, construction and demolition waste, poses significant environmental challenges. In this context, the development of Technosols (engineered soils made from waste materials) emerges as a solution to support sustainable land management, by recovering soil quality. This study aimed to evaluate the effect of Technosols constructed with different proportions of iron mining tailings (IMT) and construction and demolition waste (CDW) on pore size distribution, soil penetration resistance, and soil water retention, focusing on their potential to support plant shoot and root growth and enhance water retention. Four Technosols (TEC) were developed using iron mining tailings and construction and demolition waste at ratios of 60:40, 70:30, 80:20, and 100:00, and compared to a natural soil control (Haplic Ferrasol). The results revealed significant differences in pore size distribution ( p < 0.05), especially in the 10–100 μm range. Treatments TEC 60:40 , TEC 70:30 , and TEC 80:20 showed higher frequencies of pores in this range (ω values up to 0.14), suggesting increased microporosity and improved water retention. Additionally, TEC 60:40 and TEC 70:30 exhibited a higher proportion of macropores >150 μm (∼21% of total porosity), which favor soil aeration. Thus, TEC 70:30 offered the best balance between water retention and aeration, outperforming the Ferralsol control. Physical properties including total porosity, water retention, bulk density, and penetration resistances, showed strong relationships with both shoot and root biomass (R 2 > 0.73), indicating their central role in explaining plant growth in the constructed Technosols. Overall, these results highlight the potential of Technosols formulated from 70% IMT and 30% CDW as an effective approach to transform mining and construction waste into functional soils that sustain plant growth and restore key physical properties in degraded lands. • Technosols (TEC 70:30 ) optimises water storage, aeration and plant shoot and root biomass. • Engineered Technosols yield significantly higher shoot biomass than natural Ferralsols. • IMT and CDW mixtures transform mining and construction waste into functional soils. • Technosols modify hydraulic and mechanical behavior to facilitate root penetration.

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