Trace Metal Constraints on the Soil Methane Sink: A Tractable Lever to Enhance Methane Uptake in Managed Lands?

Uptake by soil microbes is the only biological sink for atmospheric methane (CH4). Efforts to enhance the activity of methanotrophs focus largely on managed lands such as agricultural soils, but the critical levers for enhancement remain uncertain due to unresolved constraints on methanotroph ecophysiology. We propose that trace metal limitation represents a key but underexplored constraint on uptake in agricultural soils. Specifically, we focus on copper (Cu) and lanthanum (La) – key cofactors for the central enzymes of methanotrophy. Along a forest-to-cropland gradient, we will (i) characterize Cu and La bioavailability alongside methanotroph population structure, uptake rates, and functional gene expression, and (ii) conduct systematic trace metal amendment experiments to assess whether Cu/La supplementation can enhance CH4 uptake in post-agricultural soils. This work will provide critical mechanistic insights into why agricultural soils consistently exhibit prolonged suppression of CH4 uptake activity, with direct implications for CH4 sink enhancement strategies in managed landscapes.

“Restoring microbial methane uptake in managed soils, which have lost much of their capacity to consume atmospheric methane, is a promising strategy for climate intervention. Achieving this goal requires identifying and relieving the environmental stressors that suppress methane-eating microbes. Here, we investigate trace metal limitation as a fundamental constraint on methane uptake in post-agricultural soils and test whether alleviating this limitation can substantially enhance uptake.”

Linta Reji, Assistant Professor, Geophysical Sciences