Structural and molecular evaluation of soil organic matter from integrated crop-livestock-forest systems

• Grant number: 19/02939-9
• Support type: Scholarships abroad - Research Internship - Post-doctor
• Effective date (Start): September 01, 2019
• Effective date (End): August 31, 2020
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Ladislau Martin Neto
• Grantee: Amanda Maria Tadini
• Supervisor abroad: Patrick G Hatcher
• Home Institution: Embrapa Instrumentação Agropecuária. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil
• Local de pesquisa : Old Dominion University (ODU), United States
• Associated to the scholarship: 17/22950-1 - Dynamics, reactivity and structural aspects of soil organic matter under integration crop-livestock-forest systems, BP.PD

Abstract

Soils under Integrated Crop-Livestock (ICL) and Integrated Crop-Livestock-Forest Systems (ICLF) have the potential to capture and sequester carbon in the form of tree biomass (ICLF) and increasing content of Soil Organic Matter-SOM (ICL and ICLF), contributing to the mitigation of greenhouse gas emissions in agriculture. Studies aiming to evaluate the structural aspects and the reactivity of SOM in the systems are still limited; however they are fundamental for the understanding of the chemical, physical and biological processes that influence the accumulation or not of carbon in the soils as well as other relevant soil properties, as fertility, structure and others. This project aims to evaluate the molecular and structural composition of the physical and chemical fractions of SOM from ICLF by using the following analytical techniques: Isotope analysis (13C, 12C, 15N and14N), solid-state 13C Nuclear Magnetic Resonance with Cross Polarization Magic Angle Spinning by multiple Contact Periods (13C CP/MAS NMR multi-CP), Gas Chromatography coupled to Time of Flight Mass Spectrometry (GC-TOF-MS) and Electrospray Ionization coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FTICR-MS). The results obtained until now in the Fapesp post-doctoral project (process 2017/22950-1) for the ICLF compared to native forest (reference area) showed that there was an increase in the humification index in areas with a higher content of SOM, as detected using laser-induced fluorescence spectroscopy with whole soil samples analysis. The results suggested that the organic material is accumulated in a more stable chemical form (longer life time in the soil) than the reference areas (including forests). Based on that, this research will try to go deeper in the understanding of the origin and the molecular composition of this SOM, using whole soil samples as well as soil chemical and physical fractionating techniques. Therefore, this project aims to obtain original data on the structure and molecular composition of SOM, in order to understand the main biogeochemical processes that occur in these integrated systems areas, including soil fertility and structure aspects, and helping in the advancement of understanding soil carbon sequestration mechanisms and estimate of life time of soil organic compounds.