Is wood ash amendment a suitable mitigation strategy for N₂O emissions from soil?

Area of Science:

• Soil Science
• Environmental Science
• Biogeochemistry

Background:

• Wood ash, a biomass combustion byproduct, recycles soil nutrients and counteracts acidification.
• Wood ash application can influence greenhouse gas emissions, particularly nitrous oxide (N₂O).

Purpose of the Study:

• To investigate the effect of wood ash application on N₂O emissions across diverse soil types.
• To identify key factors influencing N₂O emissions post-wood ash application.

Main Methods:

• A 40-day incubation experiment with ten soil types and five wood ash concentrations.
• Continuous measurement of N₂O emissions and analysis of soil properties (pH, C, N, NH₄⁺, NO₃^-).
• Random Forests (RF) model to determine the importance of various factors on N₂O emissions.

Main Results:

• Wood ash altered N₂O emissions, with effects dependent on soil type and ash dose.
• Final soil pH was identified as the most critical factor predicting N₂O emissions.
• Mitigation of N₂O was observed in low pH, high organic matter soils; increased emissions occurred in fertilized mineral soils.

Conclusions:

• Wood ash can mitigate soil N₂O emissions, primarily in acidic soils with high organic matter.
• The impact of wood ash on N₂O is soil-specific, influenced by initial properties and fertilization history.
• Soil pH management is crucial for controlling N₂O emissions when applying wood ash.