Modification of Sandy Soil Properties through Application of Mining Overburden

Abstract

Mining overburden consists of earth materials (rocks, saprolite, soil, etc.) on top of the target mineral resource and requires removal during the open-pit mining process. In São Paulo State, Brazil, rocks mined for aggregate production are mafic igneous intrusions within pre-Jurassic-Cretaceous sedimentary formations, which are regarded as mining overburden. These sedimentary formations may contain 2:1 phyllosilicate. In soils, these minerals significantly contribute to carbon capture and stabilization as soil organic matter, to the nutrient and water retention capacity, and also are a potential source of K ions for plant growth through mineral weathering. Therefore, mining overburden with these characteristics holds significant potential for agricultural use, particularly in sandy and degraded soils. In such a context, mining overburden rich in clay minerals can serve as a soil conditioner. To test this hypothesis, a field experiment was conducted in a sandy soil under pasture for 18 months. Five treatments were implemented: control, 0.77% basalt, 5% mining overburden, 25% mining overburden, and 5% mining overburden + 0.77% basalt. Simultaneously, litter bags containing the two rock powders were buried in both the pasture area and in the neighboring forest area. The overarching objective of this project was to evaluate and quantify these changes. The objective of this internship proposal (work package) is to perform advanced analyses in the experimental samples to characterize potential changes in the organic carbon associated with the mineral phases, and to better understand the potential of this technology to contribute to carbon capture and stabilization in a sandy soil. Concurrently, exposing the grantee to the interaction with the international scientific community is a paramount experience for her scientific education and to improve the outcomes of the project. The results are anticipated to contribute to the publication of high-impact articles.