DATA - Pasture Soils in the Southern Brazilian Highlands Are Net Methane (CH4) Sinks, Challenging Intergovernmental Panel on Climate Change (IPCC) Tier 1 Defaults

This dataset contains field measurements of soil–atmosphere methane (CH₄) exchange and associated soil environmental covariates across a pasture management intensification gradient in the Southern Brazilian Highlands (Lages, Santa Catarina, Brazil) during December 2019–December 2020. The study includes four grazing systems: natural grassland (NG), improved natural grassland (ING), cultivated perennial pasture (PP), and cultivated annual pasture (AP). Soil CH₄ fluxes were measured in 44 sampling campaigns using static chambers coupled to gas chromatography (Shimadzu GC-2014, FID). In each system, four paddocks were monitored (n = 4 replicates per system), and three chambers were installed per paddock (48 chambers total). For each sampling campaign, paddock-level fluxes correspond to the mean of three chambers to avoid pseudoreplication.

At each campaign, soil mineral nitrogen and moisture status were quantified in the 0–10 cm layer, including ammonium (NH₄⁺–N) and nitrate (NO₃⁻–N) extracted with 1 M KCl and quantified by steam distillation, as well as gravimetric moisture and water-filled pore space (WFPS). Additional sampling campaigns were conducted after fertilization and major rainfall events to capture short-lived emission peaks. The dataset supports analyses of (i) annual CH₄ balances (sink/source behavior) by management system, (ii) seasonal “hot moments” associated with rewetting and nitrogen inputs, and (iii) non-linear environmental controls on CH₄ fluxes (e.g., optimum uptake at intermediate WFPS and inhibition of CH₄ oxidation under elevated NH₄⁺).

Files provided include analysis-ready data tables, metadata (variable definitions, units, and codes), and/or scripts required to reproduce the statistical analyses and figures reported in the associated manuscript “Pasture Soils in the Southern Brazilian Highlands Are Net Methane (CH₄) Sinks, Challenging IPCC Tier 1 Defaults”. This dataset is intended for reuse in greenhouse-gas inventories, pasture management and climate-mitigation assessments, and synthesis/meta-analysis of soil CH₄ flux drivers in subtropical grassland systems.