Soil pH modulates the activity of low-affinity methane oxidation in soils from the Amazon region.

This article investigates the impact of soil pH adjustment through liming on methane uptake and the active methane-cycling microbial community in Amazonian forest and pasture soils. Using stable isotope probing with ^13CH_4 at high methane concentrations (~10,000 ppm), the study found that liming increased methane oxidation by approximately 10% in forest soils and 25% in pasture soils, with a notable stimulation of methanotrophic bacteria such as Methylocaldum spp. (Gammaproteobacteria) and members of the Beijerinckiaceae family (Alphaproteobacteria) in limed pasture soils. In limed forest soils, ammonia-oxidizing archaea from the Nitrososphaeraceae family were identified as active in methane assimilation, suggesting alternative methane oxidation pathways. The findings highlight liming as a potential management practice to enhance methane oxidation and mitigate greenhouse gas emissions in degraded tropical pasture soils, while indicating a more limited effect in forest soils.