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

Published: 27 January 2026| Version 1 | DOI: 10.17632/9wmbpf5kkj.1
Contributors:
PEDRO GARZON CAMACHO,
,

Description

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.

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Study design The study was conducted at the EPAGRI Experimental Station (Lages, Santa Catarina, Brazil) between December 2019 and December 2020. Four grazing systems representing a management intensification gradient were evaluated: natural grassland (NG), improved natural grassland (ING), cultivated perennial pasture (PP), and cultivated annual pasture (AP). Each system comprised four independent paddocks (n = 4). In each paddock, three static chambers were permanently installed (total = 48 chambers). CH₄ flux measurements Soil–atmosphere CH₄ fluxes were measured using the static chamber technique. Chambers (32 × 25 cm; area = 0.080 m²) were mounted on permanent bases with water-sealed collars. During each sampling campaign, gas samples were collected at 0, 20, and 40 minutes after chamber closure using gas-tight syringes and transferred to evacuated vials. CH₄ concentrations were analyzed by gas chromatography (Shimadzu GC-2014) equipped with a flame ionization detector (FID). Fluxes were calculated assuming linear concentration change over time and corrected for chamber air temperature. Sampling frequency and event-based measurements A total of 44 sampling campaigns were conducted over the experimental year, including routine monitoring and additional campaigns following urea fertilization events and major rainfall episodes to capture transient emission pulses. For each campaign, chamber-level fluxes were averaged at the paddock level to avoid pseudoreplication. Soil variables and environmental covariates At each sampling event, soil samples (0–10 cm) were collected adjacent to each chamber. Ammonium (NH₄⁺–N) and nitrate (NO₃⁻–N) were extracted with 1 M KCl and quantified by steam distillation. Gravimetric soil moisture was determined by oven drying, and water-filled pore space (WFPS) was calculated from volumetric water content and soil total porosity. Data processing Daily CH₄ fluxes were expressed on an area basis and integrated over time using linear interpolation to obtain annual balances for each paddock. Annual fluxes were converted to CO₂-equivalents (CO₂-eq) using the IPCC AR5 100-year global warming potential for CH₄ (GWP100 = 27.2). Statistical analysis Statistical analyses were conducted in R (v4.5.0). Paddock was considered the experimental unit. Management effects were tested using linear models with treatment as a fixed effect, followed by Tukey’s HSD for mean comparisons (α = 0.05). Environmental drivers of CH₄ fluxes were analyzed using generalized additive mixed models (GAMMs; package mgcv), including non-linear smooth terms for WFPS, NH₄⁺–N, NO₃⁻–N, and temperature. Model assumptions were evaluated through residual diagnostics. Reproducibility The dataset includes analysis-ready data tables and, where applicable, scripts required to reproduce all analyses and figures reported in the associated manuscript. Software versions, variable definitions, units, and metadata are provided to ensure full reproducibility.

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Categories

Soil Ecology, Grassland Ecology, Greenhouse Gas Mitigation, Greenhouse Gas in Soils, Climate Change Mitigation Strategies, Management of Greenhouse Gas Emissions from Information and Communication Services

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