English

Lottici Krahl Luise,De Souza Martins Éder,Marchi Giuliano,Carlos Sousa-Silva José,Simões Angélica Rômulo,Patrícia Aranha Da Paz Simone,Fonseca Valadares Leonardo

doi:10.5897/ajar2019.14546

Abstract

Basalt powder wastes from mining activities have potential to be used as a natural fertilizer. Basalt minerals in agricultural soils may release plant nutrients and increase soil negative charge. In this work, the weathering of basalt promoted by maize rhizosphere was investigated. We studied the chemical and mineralogical composition of basalt, including cation exchange capacity, as well as the rate of elements offtake by maize grown in a pure basalt powder during seven successive growth cycles. A pot experiment was carried out under controlled environmental conditions; plant and rock materials were evaluated at the end of successive growth cycles. X-ray powder diffraction analysis showed diopside and andesine as main minerals of basalt, and smectite. Scanning electron microscopy images evidenced new amorphous components resulting from rhizosphere-induced weathering. The elements K, Ca, Mg, Al, B, Cu, Fe, Mn and Zn were measured in plant tissue, and related to the weathering of basalt minerals. The studied basalt, therefore, provides nutrients to plants and exhibits physicochemical properties, such as cation exchange capacity, especially important for highly weathered soils presenting low cation exchange capacity, such as Oxisols. Key words: Bioweathering, natural fertilizer, mining waste, basalt minerals, cation exchange, nutrient availability. &nbsp

Highlights

Some silicate minerals contain high concentration of nutrients, which are required by plants for growth
The X-ray fluorescence (XRF) analysis showed that the chemical composition in basalt fractions (Table 1) was nearly uniform (Tables 2 and 3)
Significant concentration of CaO and MgO was found in all grain sizes, when compared to the basalt composition applied as fertilizers in another studies (Nunes et al, 2014; Ramos et al, 2015), even though basalt chemical composition varies widely

Summary

Introduction

Some silicate minerals contain high concentration of nutrients, which are required by plants for growth. These minerals have been used as agricultural fertilizers, releasing its nutrients slowly (Ciceri and Allanore, 2019; Manning et al, 2017; Zorb et al, 2014). Many studies where mining by-products were applied to soils have emerged, turning mining waste in products as a soil fertilizer or remineralizer.

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