Unravelling the mechanisms of carbon storage in tropical soils under biochar application

• Grant number: 24/13225-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: February 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: João Luís Nunes Carvalho
• Grantee: Fernanda Palmeira Gabetto
• Host Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Ministério da Ciência, Tecnologia e Inovação (Brasil). Campinas , SP, Brazil
• Associated research grant: 21/10573-4 - Center for Carbon Research in Tropical Agriculture (CCARBON), AP.CEPID

Abstract

An essential part of addressing ongoing climate change involves the deployment of carbon dioxide removal (CDR) technologies to offset emissions from hard-to-decarbonize sectors. However, some of them are associated with high implementation costs or low technology readiness levels. Among the feasible CDR technologies ready for implementation, biochar offers a unique approach to promoting negative net greenhouse gas (GHG) emissions, as it can promote carbon © sequestration while reducing other GHG emissions. Based on the existing literature knowledge gaps, we introduce a research framework that explores the underlying mechanisms by which biochar can affect the soil C sequestration under tropical climate conditions. To meet the main goal, this research will be divided into three complementary chapters. An incubation experiment will be carried out in the first chapter to compare biochar and straw-amended soils using the ´13C stable isotope technique to distinguish carbon dioxide (CO2) emissions derived from native soil organic matter, the recent organic amendment, and priming effect. For the second chapter, soil sampling will be performed in a long-term field experiment (9 years) with biochar application. The soil samples will be submitted to several analyses, including 3D-FIB-SEM-EDS image acquisition, soil porosity by X-ray Computed Microtomography (µ X-ray CT), enzyme activity, and functional C groups by X-ray Photoelectron Spectroscopy (XPS). Lastly, the third chapter will include an incubation experiment with the re-application of biochar after a long-period break. To evaluate the complexity of the responses, we will quantify GHG emissions throughout the experiment and assess microbial changes through DNA sequencing microbial communities. Therefore, implementing this project will help improve the understanding of the complex mechanisms that govern C stabilization in tropical soils with biochar application to elucidate the potential of using biochar as a tool for achieving C neutrality in Brazil.