Synchrotron X-ray tomography to decipher the mechanisms of carbon stabilization in Brazilian tropical soil

Abstract

Integrated crop-livestock (ICL) systems are acknowledged as promising nature-based solutions for enhancing soil carbon (C) accrual relative to crop-succession (CS) systems, but an incomplete understanding of the underlying mechanisms of this phenomenon cripples our ability to develop strategies for optimizing soil C sequestration in tropical environments. Conceptually, micro-scale heterogeneity in soil structure is understood to have substantial effects on physical protection of soil C. A recently proposed method of staining soil organics by vapors of Osmium Tetroxide with subsequent dual-energy X-ray computed microtomography (XCT) scanning enables quantitative analyses of these effects by resolving intra-aggregate pore architecture and deciphering its interactions with soil C protection within intact soil matrix. Here we present a workplan for the development of research internship abroad complementary to the activities defined in the FAPESP- BG E&P Brasil Ltda (Grupo Shell) Project (number #20/15230-5) entitled "Research Center for Greenhouse Gases Innovation (RCG2I)". Based on the hypothesis that the adoption of ICL system results in a more complex intra-aggregate pore networks that favor an effective soil C accrual compared to CS system, the objective of this proposal is to explore the interactions between soil structure, as represented by characteristics of pore space architecture (i.e., total porosity, pore-size distribution, connectivity and tortuosity), and its influence on physical protection of sequestered C from long-term adoption of ICL as compared to CS systems. This research internship will be scaled for execution over 12 months, during which intact soil samples will be collected from long-term experiments under ICL and CS systems in Brazil and shipped for XCT measurements at the Advanced Photon Sources (Lemont, IL, USA), followed by image processing and data analysis supervised by the research team led by Prof. Alexandra Kravchenko at Michigan State University. Expected results include the provision of realistic statistics on microscale intricacies of pore architecture that favor soil C protection/accrual by ICL systems as compared to CS, providing the basis for target-oriented development of management strategies to rebuild soil C in Brazilian agriculture. Lastly, the supported research internship abroad will be strategic to create an innovative and emerging research program at LNBR/CNPEM, while strengthening the partnership between research groups on future endeavors, in which scholars and scientists from both institutions will have the opportunity to exchange knowledge on a wide range of research fields and to develop joint proposals using advanced synchrotron-based tools to decipher the mechanisms controlling soil C sequestration. (AU)