The sustainability of a reseeded pasture in Southeast of Brazil assessed by the balances of turbulent fluxes (eddy covariance) of greenhouse gases (CO2, CH4 and N2O)

• Grant number: 19/22095-0
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• Start date: March 01, 2020
• End date: February 28, 2022
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Meteorology
• Principal Investigator: Osvaldo Machado Rodrigues Cabral
• Grantee: Osvaldo Machado Rodrigues Cabral
• Host Institution: Embrapa Meio-Ambiente. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). Jaguariúna , SP, Brazil
• Associated researchers: Cristiano Alberto de Andrade ; Diego Noleto Luz Pequeno ; Helber Custódio de Freitas ; Humberto Ribeiro da Rocha ; Luciano Vieira Koenigkan ; Luís Gustavo Barioni ; Sandra Furlan Nogueira ; Santiago Vianna Cuadra

Abstract

Pasture restoration and increasing animal efficiency are the basis of the livestock sector contribution to the Brazilian Nationally Determined Contribution (NDC). Moreover, those measures are aligned to the global debate on land sparing by sustainable agricultural intensification. In order to verify that continuous measurements of water vapor fluxes (evapotranspiration) and greenhouse gases (GHG): methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) will be conducted during two years a 24 ha pasture under extensive beef cattle grazing representative of the Southeast of Brazil (Pirassununga, SP).The observed fluxes represent the net ecosystem exchange (NEE) between the vegetation and the atmosphere, will be continuously measured by the eddy covariance method which has high temporal resolution (30 min) and is capable to represent several hectares of vegetation around the measuring point. The molar fractions of CH4 and N2O will be analyzed by a closed-path Quantum Cascade Laser Absorption Spectrometer (QCLAS) and the CO2 and water vapor fluxes by an open-path infrared gas analyzer and a tridimensional sonic anemometer. The pasture net ecosystem carbon balance (NECB) will be assessed considering the biomass consumed by the cattle (Bp), obtained periodically by the exclusion cages method. The net carbon balance (NECB=NEE+Bp) for this agro-system representative of the Southeast in Brazil and subjected to the intensification by restoration will define whether the system is a source or a sink to the atmospheric carbon. The data set generated will also be utilized to calibrate process-based models and evaluate the water and carbon balances between the plantation and the atmosphere. The quantification of fluxes is necessary to understand the dynamics of the biogeochemical processes, contributing for the assessment of management practices, land use changes and potential mitigating measures in the context of climate change. (AU)