POTENTIAL CO2 EMISSION FROM BRAZILIAN SOILS DETERMINED BY REFLECTANCE SPECTROSCOPY

The emission of CO₂ from the soil surface, known as soil carbon dioxide efflux (FCO₂) is key to the compression of the global carbon cycle. FCO₂ has a direct relationship with soil physicochemical attributes such as SOM quantity and quality, microbial biomass and community composition, pH and texture. Our objective was to develop a technique based on reflectance spectroscopy products, digital soil mapping and machine learning techniques, to create and spatialize a model of soil FCO₂ for the entire Brazilian territory. We obtained maps with a spatial resolution of 30 m and the FCO₂ was fitted to a multivariate regression model with an R² of 0.56. The most important and significant variables correspond to sand, asymmetric CH₂, urease and beta-glucosidase enzymatic activity, and CH. This FCO₂ map can be used as a general approximation of soil CO₂ emission potential and contribute to soil management in response to global climate change.