ECOPERSIA

ECOPERSIA

Synergistic Application of Biochar and Biofertilizer to Restore Soil Structure and Mitigate Petroleum Hydrocarbons in Iranian Coastal Ecosystems

Document Type : Original Article

Authors
Navazollah Moradi 1
Ommolbanin Bazrafshan 2
1 Department of Natural Resources Engineering, Faculty of Agriculture and Natural Resources Engineering, University of Hormozgan, Bandar-Abbas, Iran
2 Department of Natural Resources Engineering, Faculty of Agriculture and Natural Resources Engineering, University of Hormozgan, , Bandar-Abbas, Iran
10.48311/ecopersia.2026.119415.82879
Abstract
Aims: This study evaluated the combined effects of Conocarpus biochar and a Bacillus-based biofertilizer on TPH removal, aggregate stability index (ASI), and mean weight diameter of aggregates in diesel-contaminated mangrove sediments.
Materials & Methods: This study examined the synergistic effects of biochar (4% w/w) and a Bacillus subtilis-based biofertilizer (applied at 0%, 2%, and 5% v/w) on physicochemical recovery and total petroleum hydrocarbon (TPH) removal in diesel-contaminated (8% w/w) mangrove sediments collected from the Persian Gulf. A 70-day incubation experiment was conducted under controlled conditions (18–25°C, 50% field capacity).
Findings: The application of biochar significantly improved soil aggregate stability, as evidenced by increases in dry mean weight diameter (MWDdry) and the Aggregate Stability Index (ASI). In contrast, the biofertilizer alone reduced clay dispersion and turbidity, indicating enhanced colloidal stability. Biochar alone achieved the highest TPH removal efficiency (95.5%), outperforming both the 2% biofertilizer treatment (90.5%) and the untreated control (93.5%), which demonstrated substantial indigenous microbial degradation. Notably, the combined application of biochar with 2% biofertilizer resulted in reduced remediation efficiency (86%), suggesting antagonistic interactions at lower microbial doses. However, when biochar was combined with the higher biofertilizer dose (5%), both structural integrity and TPH removal (95%) were effectively restored, revealing a dose-dependent synergy.
Conclusion: The results indicated that while biochar primarily functions as a physical stabilizer, especially under wet conditions, microbial amendments must be carefully dosed to avoid disrupting native microbial communities. Effective remediation of petroleum-polluted saline soils thus depends on a balanced integration of physical amendments and microbial ecology, rather than additive application alone.
Keywords
Bacillus subtilis
Bioremediation
Mangrove sediments
Petroleum contamination
Soil aggregate stability
TPH removal
Subjects
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