CARBON (C) SATURATION, MODELING, AND FERTILITY IN TROPICAL SOILS: A NATIONAL APPROACH.

• Grant number: 24/15908-2
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: May 01, 2025
• End date: April 30, 2028
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Carlos Alexandre Costa Crusciol
• Grantee: Laudelino Vieira da Mota Neto
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 23/02444-5 - Understanding intensified and integrated production systems: from the quantum world to low-carbon agriculture, AP.PFPMCG.TEM

Abstract

The present proposal will test whether Brazilian soils accept the C saturation hypothesis. Data from Embrapa will be used to estimate the organic carbon of the fraction associated with minerals (COAM) using a machine-learning Random Forest model. The COAM will be plotted as a function of the soil's silt+clay content. Testing this hypothesis is paramount to establish metrics regarding the potential for C sequestration in the soil profile (0-100 cm) and its impact on Brazil's mitigation goals until 2030 for climate neutrality with the United Nations (UN). Furthermore, the present proposal will test the hypothesis that high doses of lime aimed at increasing subsoil fertility associated with the application of gypsum result in systems with a positive C balance, without negative effects on plant and grain nutrition. This hypothesis will be tested in a long-term experiment started in 2002 belonging to the College of Agricultural Sciences at UNESP, Botucatu - SP, currently registered in the Global Network of Long-term Experiments, controlled by the Rothamsted Research Institute, UK (GLTEN). It is worth clarifying that the dynamics of C in this system receiving doses of lime in association or not with the application of gypsum remains unexplored to date. Furthermore, this proposal will evaluate the effect of soil fertility management with lime and gypsum application on C dynamics through simulations with the DayCent model, using data from climate simulations that consider the increase in the planet's temperature in this century. To this end, data observed in the long-term experiment, with well-defined local and historical control, will be included for calibration and validation of the simulations.