Biochar formulation determines soil improvement and fertiliser synergy during Eucalyptus globulus plantation establishment
Year: 2026
Type: preprint
Abstract: Biochar produced from forest biomass residues can link renewable bioresource valorisation, soil improvement and fertiliser-use efficiency in planted forests. This study evaluated a high-carbon Biochar Pure and a mineral-enriched Biochar Plus, applied with and without mineral fertilisation, in an acidic Mediterranean Eucalyptus globulus plantation in central Portugal. Six treatments were assessed in the flat area and three in the terraced area, each with three replicated blocks. Mineral fertilisation increased plant height by 57% at 5 months and 117% at 12 months relative to the unfertilised control. Biochar Pure alone produced no growth response, whereas Biochar Plus without NPK increased height by 29% and 75%, respectively. Combined treatments produced the strongest response, reaching + 175% at 12 months. A descriptive Biochar–Fertiliser Synergy Index of 1.50 indicated a supra-additive response for Biochar Pure combined with mineral fertilisation. Biochar increased soil pH by 0.3–0.6 units at the first post-planting sampling, organic carbon concentration by 46–52% at 12 months, and cation exchange capacity by 81–108% at the first sampling. The Forest Soil Quality Index reached 0.770, while the Integrated Eucalypt Growth Index peaked at 1.525, showing that improved soil condition translated most strongly into plant performance when biochar was combined with fertilisation. Overall, Eucalyptus -derived biochar improved soil chemical condition and enhanced fertilisation efficiency during early plantation establishment. The findings support its use as a functional forest bioproduct for soil regeneration and circular biomass utilisation in Mediterranean fibre-production systems.
Source: Research Square
Institution: University of Aveiro
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7204159592