Sustainable intensification of Brazilian pastures: soil health assessment and carbon sequestration

• Ano de defesa: 2025
• Autor(a) principal: Castro, José Igor Almeida
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Carbon sequestration; Intensificação sustentável; Pasture systems; Saúde do solo; Sequestro de carbono; Sistemas de pastagem; Soil health; Sustainable intensification
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11140/tde-01122025-121149/

Brazil\'s extensive pasturelands, crucial for global food production, are facing widespread degradation, creating an urgent need for sustainable intensification. This transition is central to the country\'s climate commitments, yet it requires a robust scientific foundation to guide policy and practice. This thesis addresses this need through a two-part investigation, moving from a broad methodological assessment to a focused quantitative analysis. The first chapter presents a systematic review of 64 studies (2014-2024) to map the intellectual and methodological structure of soil health assessment in managed Brazilian pastures. The analysis reveals a strong geographical concentration of research in the Cerrado and Atlantic Forest biomes and a methodological maturation towards quantitative integration frameworks. A foundational triad of indicators, soil organic carbon (SOC), pH, and bulk density, was identified as the operational core of these assessments, with network analysis confirming them as hubs connecting distinct research themes. Building on the finding that SOC is the most central indicator, the second chapter conducts a meta-analysis of 50 studies to quantify the impact of converting low-productivity pastures into improved and integrated systems on SOC stocks. The results show an average increase in SOC stocks of 15.3% (95% CI: 10.4-20.5%) across all interventions. System-specific management factors (MF) were derived, ranging from 1.12 for Crop-Livestock Systems (CLS) to 1.40 for Crop-Livestock-Forestry Systems (CLFS) after 20 years of management in the 0-100 cm soil profile. Consequently, estimated annual SOC change rates (ΔC) for this scenario ranged from 0.75 Mg C ha-1 yr-1 in CLS to 2.42 Mg C ha-1 yr-1 in CLFS. Extrapolated to a national scale, these rates represent a maximum technical mitigation potential exceeding 800 Mt CO2eq yr-1, with plausible policy-driven adoption scenarios capable of achieving over 330 Mt CO2eq yr-1 annually. Collectively, this thesis provides a strategic roadmap of the current research landscape and delivers robust, system-specific carbon change factors. These findings offer an evidence based foundation to support the design and monitoring of effective policies aimed at enhancing the productivity, resilience, and climate mitigation potential of Brazil\'s vital pasturelands.