Microbial Community Dynamics in Wood Ash-Amended Soils

Wood ash amendment is increasingly adopted to recycle nutrients, counteract soil acidification and enhance forest and agricultural sustainability. The alkaline nature of wood ash rapidly raises soil pH and electrical conductivity, triggering shifts in microbial abundance, diversity and function. Initial pH increases favour copiotrophic bacteria that thrive on enhanced nutrient availability, while acidophilic and oligotrophic taxa decline. Vertical gradients develop in surface layers, where exchangeable cations and pH peaks drive community stratification that diminishes with depth. Functional gene expression and microbial activity adapt to these new physicochemical conditions, with elevated expression of metabolism and growth pathways in bacteria and concurrent effects on protozoan grazers. Over time, changes in microbial-driven processes such as nitrogen mineralisation, carbon turnover and enzyme activities influence soil fertility, carbon sequestration and broader biogeochemical cycles. Understanding these dynamics is crucial for optimising ash application rates, preventing negative impacts on sensitive taxa and harnessing microbial functions that support plant growth and mitigate climate change.

Research from Nature Portfolio

Research employing micro-vertical profiling in forest soil mesocosms has revealed that surface applications of wood ash (3–9 t ha⁻¹) produce steep pH and cation gradients confined to the top few centimetres. These gradients correlate with pronounced shifts in prokaryotic community structure: copiotrophic groups proliferate near the surface at the expense of oligotrophic and acidophilic taxa, while deeper layers remain largely unaffected. Temporal monitoring over one year shows that community changes persist in the topsoil, emphasising the spatially restricted nature of ash-driven microbial responses and underscoring the importance of dose and depth in management strategies.

Microbial Community Dynamics in Wood Ash-Amended Soils publication trend

The graph below shows the total number of articles in microbial community dynamics in wood ash-amended soils across all publications each year (not limited to Nature Index journals).

Technical terms

Copiotrophic bacteria: Microorganisms that grow rapidly in nutrient-rich environments.

Oligotrophic bacteria: Taxa adapted to low-nutrient conditions, often slow-growing.

Rhizosphere: The soil region directly influenced by root exudates and associated microbes.

pH: A logarithmic scale indicating soil acidity or alkalinity.

Total RNA sequencing: A method to profile active microbial communities by sequencing all RNA transcripts.

References

1. Total RNA sequencing reveals multilevel microbial community changes and functional responses to wood ash application in agricultural and forest soil. FEMS Microbiology Ecology (2020).
2. Application of wood ash leads to strong vertical gradients in soil pH changing prokaryotic community structure in forest top soil. Scientific Reports (2021).
3. Enhancing organic and inorganic carbon sequestration in calcareous soil by the combination of wheat straw and wood ash and/or lime. PLOS ONE (2018).
4. Comparison of the Effect of Fertilization with Ash from Wood Chips on Bacterial Community in Podzolic and Chernozem Soils for the Cultivation of Winter Oilseed Rape: A Preliminary Study. Agronomy (2022).