Linking microbes and metabolites between litter and soil interface: organic carbon and soil health in a chronosequence of Amazonian agroforestry

• Grant number: 24/06334-2
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 01, 2024
• End date: August 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Tsai Siu Mui
• Grantee: Guilherme Lucio Martins
• Supervisor: Gerd Gleixner
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: Max-Planck-Institut Für Biogeochemie, Germany
• Associated to the scholarship: 22/05561-0 - SOIL BIODIVERSITY AS THE CENTRAL ROLE OF PLANT-SOIL FEEDBACKS IN AMAZON AGROFORESTRY SYSTEMS, BP.DR

Abstract

The 'detritusphere', the zone of soil under direct influence of decaying litter, is a dynamic zone rich in organic matter, microbial biomass, and activity, with high rates of organic matter flow. This interface is crucial in the Amazon region, where most of the soils are highly weathered with low organic matter and nutrient content, making the organic matter turnover from aboveground to belowground essential for energy and nutrient fluxes to microbes and plants. Amazonian agroforestry systems (AFS) are crucial for both forest conservation and small-farm livelihoods but rely heavily on nutrient cycling by soil microbes due to minimal external inputs of fertilizers. Hence, this proposal aims to evaluate how soil dissolved organic matter (DOM) from litter and soil affects soil microbial community and their functions related on carbon and phosphorus cycling in this detritusphere zone. These effects will be evaluated in sixty samples from an AFS chronosequence of 10 to 30 years, and it will be compared with primary forests, pasture, and monoculture of citrus areas. For this, we will employ a combination of techniques, including metabolomics for DOM, soil microbial metagenomics, and soil isotopic analysis. These techniques can reveal the microbial pathways for litter decomposition, and the transformation of this organic matter into various soil molecules. This information can help to identify management practices to promote either faster organic matter turnover to enhance nutrient cycling or slower turnover to improve organic carbon storage. The collaboration with Prof. Gerd Gleixner's group at the Max Planck Institute for Biogeochemistry will be vital. Their expertise and state-of-the-art facilities will be valuable in understanding the ecological and mechanistic processes of DOM in Amazonian soils. The combination of High-Resolution Mass Spectrometry and shotgun metagenomics will help us unravel the complex interactions within this crucial interface between above and belowground processes.