Pulse Brain · Growing Health Evidence Index
Tier 3 — Observational / field trialPeer-reviewed

Wood Ash as an Additive in Biomass Pyrolysis: Effects on Biochar Yield, Properties, and Agricultural Performance

Jannis Grafmüller, Alexandra Böhm, Yiling Zhuang, Stephanie Spahr, Pascale Müller, Thomas Otto, Thomas D. Bucheli, Jens Leifeld, Robin Giger, Michael Tobler, Hans‐Peter Schmidt, Nicolaus Dahmen, Nikolas Hagemann

ACS Sustainable Chemistry & Engineering · 2022

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Summary

This laboratory pyrolysis study demonstrates that wood ash amendment significantly enhances biochar yield and carbon-conversion efficiency when added at 9 wt% to softwood feedstock, with yield increases up to 26% and carbon-conversion efficiency up to 36%. Although ash addition reduced some biochar properties (micropore surface area and thermal stability), it elevated potassium content and electron exchange capacity, whilst maintaining safety margins for organic pollutants. The findings suggest ash-amended biochar offers promise for integrated nutrient recycling and carbon sequestration in agricultural soils.

UK applicability

These findings are relevant to UK biochar production and soil amendment practices, particularly for waste biomass valorisation and nutrient recovery from wood processing residues. However, applicability depends on the availability of softwood feedstock and whether pyrolysis conditions can be optimised for UK-sourced biomass and target soil types.

Key measures

Biochar yield (dry and ash-free basis), carbon-conversion efficiency, polycyclic aromatic hydrocarbon content, polychlorinated organic pollutant content, electron exchange capacity, micropore specific surface area, thermal stability, potassium content, sunflower growth promotion

Outcomes reported

The study measured biochar yield, carbon-conversion efficiency, chemical properties (PAH and PCOP content, electron exchange capacity, micropore surface area, thermal stability), and agronomic performance (sunflower growth) under varying ash addition rates, temperatures, and residence times. Results quantified the effects of wood ash amendment on pyrolysis outcomes and biochar safety for soil application.

Theme
Farming systems, soils & land use
Subject
Soil fertility & nutrient management
Study type
Research
Study design
Field trial / Laboratory experiment
Source type
Peer-reviewed study
Status
Published
Geography
Europe
System type
Laboratory / in vitro
DOI
10.1021/acssuschemeng.1c07694
Catalogue ID
BFmovi21by-7j79fu

Topic tags

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