Mitigation of soil nitrous oxide emissions during maize production with basalt amendments

Summary

This greenhouse study examined whether fine-grained basalt amendments—being explored as a carbon dioxide removal pathway—can simultaneously mitigate soil nitrous oxide emissions during maize production. Using continuous measurements and machine learning analysis of large-scale mesocosms, the authors found that basalt additions reduced cumulative N₂O emissions by 29–32%, with application rate, soil pH, and surface moisture emerging as the strongest environmental levers. The findings provide empirical support for enhanced rock weathering of silicates as a potentially significant co-benefit strategy on managed agricultural lands with high reactive nitrogen inputs.

Regional applicability

The study was conducted in a greenhouse setting in the United States using mesocosms, which limits direct transferability to United Kingdom field conditions. However, the mitigation of N₂O emissions from maize-intensive arable systems is relevant to UK agriculture, particularly given nitrogen fertiliser application practices and climate commitments. Validation in UK soil types and climatic conditions would be required before widespread adoption recommendations.

Key measures

Cumulative N₂O emissions (percentage reduction); basalt application rate; soil pH; surface soil moisture; N₂O flux measurements

Outcomes reported

The study measured cumulative N₂O fluxes from maize mesocosms in a greenhouse setting with and without basalt amendments. Researchers identified the relative importance of environmental and management factors (basalt application rate, soil pH, surface soil moisture) on N₂O emissions using machine learning.

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