Pelletization and Fertilization Improve the Root Environment in Soil Affected by Iron Mining Tailings

Iron mining tailings raise several concerns regarding their deposition and the decommissioning of storage dams, particularly regarding the limitations of this substrate for plant establishment, including poor substrate aggregation and limited availability of nutrients. The objective of this study was to evaluate the effect of the interaction of pelleting and fertilization on the physical and chemical conditioning of the root environment for the growth and development of plants in technosol formed by the deposition of iron mining tailings. Three experimental trials were carried out using indicator plants ( Urochloa brizantha Hochst. ex A. Rich., Eucalyptus grandis W. Hill ex Maiden, and Phaseolus vulgaris L.), in a randomized block design, and the treatments distributed in a factorial arrangement (5 × 2): five levels of technosol pelleting (0, 25, 50, 75, and 100% m/m), with and without fertilization, with five replications. Fertilization promoted the growth of all plants and demonstrated that the supply of nutrients is fundamental for plant growth in this technosol, mainly by promoting root development, which in turn favored substrate porosity. Pelleting mainly increased the technosol macroporosity in all tests. However, it was only effective in providing better growth conditions and enhancing the supply of nutrients for Eucalyptus grandis . While pelleting improves the physical conditions of the root environment, the availability of nutrients was found to be the main limiting factor for plant growth in the technosol formed by iron mining tailings. With adequate fertilization, the plants had less difficulty developing in this substrate under vase conditions.