Orobator 2025 - Bushfire effects on oil-palm plantation soil metals
Orobator compared Pb, Cd, Co, Cr, Ni, As, and V in unburnt and burnt oil-palm plantation topsoil in Edo State, Nigeria. This is supply-chain pathway and source-attribution context for plantation soil disturbance, not palm-oil occurrence evidence.
Key numbers
The study collected 20 topsoil samples from 0-15 cm depth: 10 from an unburnt oil-palm plantation and 10 from an adjacent burnt oil-palm plantation. Table 1 reports higher means for every measured metal in the burnt plantation soil.
Table 1 concentrations are reported in mg kg-1:
| Soil parameter | Unburnt range | Unburnt mean | Unburnt SD | Burnt range | Burnt mean | Burnt SD | p-value | WHO limit |
|---|---|---|---|---|---|---|---|---|
| Pb | 10.38-14.04 | 11.87 | 1.37 | 10.41-22.40 | 15.15 | 4.09 | 0.01* | 85.00 |
| Cd | 0.08-0.19 | 0.15 | 0.03 | 0.15-0.33 | 0.20 | 0.06 | 0.00* | 0.80 |
| Co | 2.05-4.61 | 3.63 | 0.77 | 3.72-8.20 | 5.09 | 1.48 | 0.00* | 24.00 |
| Cr | 2.61-5.89 | 4.62 | 0.97 | 4.70-10.50 | 6.52 | 1.90 | 0.00* | 100.00 |
| Ni | 2.20-4.98 | 3.93 | 0.83 | 4.01-8.50 | 5.42 | 1.54 | 0.00* | 35.00 |
| As | 1.28-2.87 | 2.26 | 0.47 | 2.30-5.12 | 3.19 | 0.95 | 0.00* | 0.80 |
| V | 0.85-2.01 | 1.52 | 0.34 | 1.55-3.42 | 2.12 | 0.62 | 0.00* | Not specified |
The abstract states that the burnt oil-palm plantation had higher Pb 15.15 mg kg-1, Cd 0.20 mg kg-1, Co 5.09 mg kg-1, Cr 6.52 mg kg-1, Ni 5.42 mg kg-1, As 3.19 mg kg-1, and V 2.12 mg kg-1. The conclusion states that higher As concentrations were observed in soils from both oil-palm plantations compared with the permissible limit.
The paper attributes higher burnt-soil values to bushfire effects including ash deposition, biomass burning, and post-fire mobilization. It also discusses fertilizer, pesticides, herbicides, and agrochemical use as possible contributors to metal presence in unburnt plantation soil.
Methods (brief)
The study used adjacent unburnt and burnt oil-palm plantations in Okunuvbe community, Edo State. A grid sampling design and systematic random sampling produced 10 topsoil samples per plantation. Pb, Cd, Co, Cr, Ni, As, and V were measured by Perkin-Elmer Analyst 300 Atomic Absorption Spectrophotometer and reported in mg kg-1. Student t-tests compared unburnt and burnt plantation means.
Implications
Certification: Do not use these soil concentrations as palm-oil occurrence values. They are plantation-soil pathway values and should remain outside product threshold math.
Courses: Strong example of an environmental disturbance pathway: bushfire increased every measured metal mean in oil-palm plantation topsoil, with As above the paper’s listed WHO limit in both unburnt and burnt soils.
App: Context only. The source supports geographic and fire-disturbance questions for plantation-soil due diligence, not consumer product scoring.
Wiki pages this source may touch
- soil-to-plant-transfer
- source-attribution-environmental-burden-apportionment
- arsenic
- cadmium
- lead
- chromium
- nickel
- vanadium
Verification notes
Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. The old skip treated plantation soil without palm-oil samples as out of scope. On reading, it is in-scope a3 pathway/source-attribution evidence because it measures heavy-metal changes in oil-palm plantation soil after bushfire.
Numbers were checked against the abstract, Table 1, and the metal-specific results sections. Chromium is total Cr, not Cr(VI). Arsenic is total As, not inorganic arsenic. Products and ingredients are intentionally empty.
Page history
The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
|---|---|---|
| 8a4982e | 2026-06-10 | recover-ingest 2026-06-10: orobator2025-oil-palm-bushfire-soil-metals (lane a3, was skip:not-food-occurrence) |