Changing a sandy soil with K-clays from mining waste to endure the climate change

• Grant number: 24/16600-1
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2025
• End date: July 31, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Antonio Carlos de Azevedo
• Grantee: Antonio Carlos de Azevedo
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated researchers: David Andrew Charles Manning ; Fabio Ramos Dias de Andrade ; Gabriel Ramatis Pugliese Andrade ; Jean Pierre Tchouankoue ; Paulo César Boggiani

Abstract

Soil is fundamental to the global production of biomass and an important carbon reservoir, both due to its size and to the possibility of manipulation through agricultural practices. Sandy soils, that is, those with a sandy surface texture (less than 15% clay) cover 25% of São Paulo's territory. Among them, Neossolos Quartzarenicos stand out for their low capacity to retain moisture and nutrients, resulting in low biomass production and carbon stock. A significant portion of these soils is found in the Western Plateau of São Paulo, often supporting degraded pastures. New strategies considering their recovery using nature-based technologies, promoting circular economy, and accessible to the socioeconomically marginalized rural populations are even more urgent in the context of global climate change. The use of K-clays (2:1 phyllosilicates with K in interlayers) to improve these soils has great potential to promote these objectives because, through bioweathering, the K in clay interlayers can turn available to plants and to the soil microbiome, increasing the biomass production capacity of sandy soils. Thus, this study aims to i) monitor the changes in a sandy soil by the addition of K-clays present in some of the sedimentary formations of the Peripheral Depression of São Paulo, ii) quantify possible increases in K availability, increase in CEC, increase in water retention capacity and in soil carbon content through monitoring soil physical, chemical, and mineralogical properties; iii) create business opportunities for mining companies in the Peripheral Depression of São Paulo (PDSP), by using mining spoils (waste) from certain geological formations as agricultural amendments. This project resonates with several national and international initiatives to address global climate change, such as the National Program for Conversion of Degraded Pastures into Sustainable Agricultural and Forestry Production Systems (PNCPD, Federal Decree 11,815, December 2023), the UN Decade of Ecosystem Restoration (2021-2030), and the general guidelines of the IPCC in addressing global climate change. (AU)