Pedotransfer and spectrotransfer applied to soil organic carbon at the national scale using machine learning.

• Grant number: 25/17418-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: August 31, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Carlos Eduardo Pellegrino Cerri
• Grantee: Lucas Baesteiro Caldeira
• Host Institution: CENTRO ESTUDOS CARBONO AGRICULTURA TROPICAL/USP
• Associated research grant: 21/10573-4 - Center for Carbon Research in Tropical Agriculture (CCARBON), AP.CEPID

Abstract

Soil Organic Carbon (SOC) is a key component of organic matter and plays a central role in the global carbon cycle. Its quantification is essential for estimating carbon sequestration, assessing soil quality, and formulating sustainable policies. In Brazil, most available data has been obtained using the Walkley-Black method, which underestimates actual carbon content due to its low oxidative efficiency. Dry combustion, although more accurate and environmentally safe, is limited by its cost, which hinders large-scale application.This project proposes the systematization of the national SOC database organized by the GeoCiS group (USP/ESALQ), integrating data from dry combustion, Walkley-Black, and VIS-NIR/MIR spectra, with the goal of developing pedotransfer and spectrotransfer functions that allow the conversion of WB values into dry combustion equivalents with high precision. Machine learning techniques will be used to calibrate and validate the models, along with clustering and outlier detection methods to identify samples with low representativeness and guide future laboratory analyses.The proposal is unprecedented in its national scope, use of integrated spectral data, and application of modern algorithms, offering a solid methodological basis for carbon data standardization and supporting future stages of high-resolution digital soil mapping. Results will be disseminated through scientific publications, technical events, and accessible digital materials, contributing to strategic initiatives such as the CCarbon thematic project and strengthening national capacity for soil carbon monitoring in alignment with global environmental agendas.