Green Manure as an Alternative for Soil Recovery in a Bauxite Mining Environment in Southeast Brazil

Abstract

The objective of this study was to evaluate plant cover and dry mass produced by green manures and their influence on the chemical attributes of soil for the ecological restoration of an area around bauxite mine environment in Southeast Brazil. Soil preparation, chemical fertilization and sowing of three species of green manures were carried out: Cajanus cajan, Crotalaria juncea and Stylosanthes guianensis. In general, C. cajan and C. juncea showed the best performance in plant cover. C. cajan and S. guianensis produced more phytomass. Green manures were efficient to promote rapid plant cover and increase in soil organic matter and total-N contents in all treatments. Therefore, green manure is a viable alternative that contributes to the success of ecological restoration projects in areas in the bauxite mining environment.

Complementing seedling planting with nucleation techniques increases forest restoration potential in areas around bauxite mining

“…Thus, the floristic results found in the census of standing vegetation show the contributions of the implemented restoration techniques. For example, the seeds that arrived in the area due to topsoil transposition, direct seeding, and green manuring; propagules dispersed by planted trees; attraction of seed‐dispersing fauna by zoochoric species due to implanting artificial perches; and species that do not belong to the restoration techniques and thus arrived via seed dispersal in the SPN (Aslan et al, 2019; Corlett, 2017; Fonseca et al, 2023; Fonseca & Martins, 2021; Viani et al, 2015).…”

“…In January 2017, the Companhia Brasileira de Alumínio carried out soil preparation in both areas with a ripper subsoiler at a depth of 60 cm to break the compacted layer and homogenize the soil surface (Figure 3). Then, acidity was corrected in the total area with 4 tons ha −1 of limestone and fertilization with 2 tons ha −1 of reactive phosphate rock and 1 ton ha −1 of NPK 10‐30‐10 (Fonseca et al, 2023). Next, three species of green manures were sown: Cajanus cajan L. Millsp; Crotalaria juncea L.; and Stylosanthes guianensis Aubl.…”

“…Next, three species of green manures were sown: Cajanus cajan L. Millsp; Crotalaria juncea L.; and Stylosanthes guianensis Aubl. Sw, and seedlings of 18 native tree species with different successional characteristics were planted in a spacing of 4 Â 4 m (630 seedlings ha À1 ) (Fonseca et al, 2023). Approximately 35 seedlings of each species were planted, with an average height of 1 m.…”

“…The passive restoration method promotes the spontaneous recovery of vegetation by removing the disturbance source and is considered cost-effective in tropical ecosystems (Crouzeilles et al, 2017;Holl, 2017;Jakovac et al, 2022;Tonetti et al, 2022;Villa et al, 2019). Conversely, the active restoration method consists of direct anthropic intervention through techniques such as seedling planting in rows, green manure, and nucleation, aiming to accelerate the recovery process of forest structure and biodiversity (Campanharo et al, 2021;Fonseca et al, 2023). Nucleation techniques are based on the successional theory proposed by Yarranton and Morrison (1974), which aims to create microhabitats that favor natural regeneration and facilitate ecological succession (Piaia et al, 2020;Silva et al, 2022).…”

“…Most of these impacts can occur directly in mineral exploration deposits, which are generally small areas (Cosimo et al, 2021; Spletozer et al, 2021; Yadav et al, 2022). However, these impacts can also occur indirectly in areas surrounding the mining deposits, such as processing sectors of the ore, tailings dams, machine traffic areas, administrative sectors, parking lots, and associated infrastructure, which altogether sum up large areas (Fonseca et al, 2023; Hund et al, 2017; Lewis et al, 2023; Lopes et al, 2021).…”