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Wood ash secondary resource

Heterogeneous mineral-rich residue of wood combustion, represented here by hardened wood ash supplied by Ljungbyverket, Sydkraft varme, Sweden. The tested ash was ground to 0.10-0.25 mm and used as a nutrient-bearing amendment in laboratory seedling pots. Its composition and treatment are sample-specific; the paper does not resolve a bottom-ash versus fly-ash fraction or a detailed wood-fuel blend. This resource is distinct from coal fly ash, sewage-sludge incineration ash, mixed municipal-waste ash, unburned wood and isolated phosphate minerals. No constituent criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

Ectomycorrhizal-associated phosphate mobilisation in wood-ash-amended pots

bioleaching Microbial

Spruce seedlings colonised by the source-designated Piloderma sp. 1 isolate 67 had higher phosphate concentrations in the ash-containing outer-compartment soil solution than non-mycorrhizal seedlings or the other tested fungi. This supports a treatment-associated phosphate-mobilisation effect, but total phosphorus mobilisation and plant phosphorus content did not show a statistically significant increase relative to the non-mycorrhizal control. The background microbiota and roots prevent attribution of all ash dissolution to the inoculated fungus. Oxalate-driven dissolution and selective calcium uptake are proposed explanations, not directly isolated causal pathways or an isolated-product recovery process.

Experimental Context & Analytical Limits:
Sections 2.1-2.2 describe living mycorrhizal associations with Picea abies seedlings, using Piloderma croceum isolates 02 and 24, Piloderma sp. 1 isolates 35 and 67, and unidentified Ha-96-3 isolate 78, originally obtained from Torup spruce roots. Seedlings with more than 75% colonised root tips were selected. Plastic pots measuring 9 by 9 by 10 cm contained acid-washed sand and peat (1:1 v/v). A 50-micrometre nylon mesh separated the roots from an outer mycelial compartment amended with 6 g/L of the ground hardened ash, or left without ash. Low- and high-nitrogen treatments received 1 or 2 g/L methylene urea fertiliser containing 39% N. Five replicate pots per treatment were randomised in a phytotron for 120 days, with 18/16 degrees C and 18/6-hour day/night cycles, 80% relative humidity and 300 micromol/m2/s PAR. Elemental analyses and the reported phosphorus budgets concern high-N arms. Controls were non-mycorrhizal seedlings and no-ash treatments, not axenic, plant-free or pH-matched controls. Soil solutions were centrifuged from outer-compartment soil and analysed for phosphate and oxalate by ion chromatography; plant elements were measured after nitric-acid digestion by ICP-AES, and microbial P by fumigation extraction. No molecular identity or species-level identifier is assigned to Piloderma sp. 1 or Ha-96-3.
Curated Evidence Points:
Sections 2.2-2.9 and 3.3, Table 1 and Figure 3 establish feed composition, conditions and the solution endpoint. Table 1 reports 17 mg P/g ash, 94 mg K/g, 260 mg Ca/g and 24 mg Mg/g, with means of two determinations. Figure 3 shows the higher phosphate concentration for Piloderma sp. 1 (67) in high-N +Ash pots, and section 3.3 reports P=0.009. The high-N +Ash comparator groups share a different statistical letter. This is a concentration in extracted soil solution, not a rate or phosphorus-recovery percentage. Final solution pH was reported as 6.4 plus or minus 0.1 with ash and 4.5 plus or minus 0.1 without ash, without a matched pH control.
Section 3.4 and Table 4 report total mobilised P of 2.2 plus or minus 0.2 mg for non-mycorrhizal high-N +Ash pots and 2.2 plus or minus 0.06 mg for Piloderma sp. 1 (67), with the same statistical group; P. croceum (02) was also in that group at 2.1 plus or minus 0.1 mg. Ha-96-3 (78) was lower at 1.7 plus or minus 0.1 mg. Values are means and SEM of five replicates. The source expresses total mobilisation as only 5.0-6.7% of P initially supplied in ash, distributed among solution, microbial biomass and plants; this is not a fungus-attributable extraction efficiency or purified yield. The no-ash arms also contained mobilised P, and no isotope-based source partition or complete residual-ash mass balance is shown. Figure 2d and Table 4 do not demonstrate increased plant P with Piloderma sp. 1 compared with the non-mycorrhizal +Ash control. Most source P remained unavailable under these assay conditions.
Sections 3.1-3.5 and 4, Tables 2-5 and Figures 1-4 distinguish ash effects from fungal effects. Ash stimulated plant growth in non-mycorrhizal as well as inoculated pots. Table 3 shows higher root Ca concentration with Piloderma sp. 1, but total plant uptake cannot establish ash-specific provenance or selective fungal transport. Oxalate concentrations were 1-6 micromol/L with no differences among treatments. Increased bacterial activity after ash addition did not differ significantly by mycorrhizal inoculation, and background fungal biomarkers were present in controls. The discussion's broad statement of no biomass effect contrasts with its own reported increase in fungal PLFA after ash addition; no universal biomass response is inferred. Neither field deployment, a uniquely demonstrated organic-acid mechanism, complete nutrient recovery nor general fertiliser safety follows from these laboratory observations.
Context_only Source: ncbi_80663
The current authority verifies Piloderma croceum as a species name for the comparator. It neither identifies Piloderma sp. 1 as P. croceum nor independently authenticates isolates 02 and 24; experimental labels are preserved without strain/genome mappings.

Sources & References

  1. mahmood_2003: Mahmood, Finlay, Fransson and Wallander (2003). Effects of hardened wood ash on microbial activity, plant growth and nutrient uptake by ectomycorrhizal spruce seedlings. FEMS Microbiology Ecology 43(1):121-131. Publisher DOI 10.1111/j.1574-6941.2003.tb01051.x and legacy DOI 10.1016/S0168-6496(02)00380-X identify the same article, not independent experiments. Complete original publisher HTML, Tables 1-5 and original Figures 1-4 inspected; the official PDF route was inaccessible. No separate supplement is announced in the inspected original.
    https://doi.org/10.1111/j.1574-6941.2003.tb01051.x (accessed 2026-10-15)
  2. ncbi_80663: NCBI Taxonomy 80663, Piloderma croceum, current species-level authority. This resolves the named comparator species, not the unidentified Piloderma sp. 1 or the identities of particular experimental isolates.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=80663 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T13:54:25.489890+00:00 Codex (GPT-6; codex) CREATE Created a distinct wood-ash secondary-resource record from a complete primary pot study, retaining solution versus total-P endpoints, null plant-P benefit, nonaxenic controls and unresolved fungal identity.
2026-10-15T14:07:25.298757Z Codex (GPT-6; codex) EDIT Clarified the total and plant phosphorus null as no statistically significant increase, following independent finding F1 in 20261015T140555Z-wood-ash-round96-statistical-wording-initial. Numerical means, source limitations and the separate solution-phosphate observation are unchanged.

Record source: data/records/wood-ash.yaml