Gneiss and steatite vermicomposted with organic residues: release of nutrients and heavy metals

Abstract

Purpose Use of silicate rock powders as fertilizer improves nutrient cycling, thus benefitting agriculture. The availability of nutrients to plants is often low, but can be increased when rock powder is vermicomposted and added. However, these powders can be rich in heavy metals, which may impair their use. We evaluated maize growth and heavy metals in plants and soil after fertilization with vermicomposted gneiss or steatite powders. Method Vermicompost was prepared with cattle manure, with or without gneiss or steatite powders. The experimental units were kept in the dark at room temperature for 70 days. Subsequently, a greenhouse experiment was carried out with maize grown in highly weathered oxisol soil and fertilized with vermicompost alone, or with gneiss or steatite powder. Results A small proportion of heavy metals was immobilized in the earthworm bodies, but did not hinder their growth. Maize growth was superior in the treatment with vermicomposted gneiss powder. The gneiss-enriched treatment contributed to increased Zn concentration in plants and may also be an alternative to Zn fertilization. High Ni and Cr concentrations in steatite powder apparently induced higher levels of these elements in plants. However, metal concentrations in the soil after cultivation in all the treatments were below acceptable limits. Conclusion Increased plant growth in gneiss-enriched vermicompost suggests the possibility of using this material to enrich vermicompost with nutrients, thus improving the chemical quality of organic fertilizer. Use of steatite powder in agriculture deserves further investigation.

Liberação de potássio e sódio a partir de resíduos do beneficiamento de rochas ornamentais

“…Embora não tenha sido objeto de estudo nessa pesquisa, sempre será necessário avaliar a presença de metais pesados em resíduos, principalmente quando se pretende a aplicação no solo ou mesmo seu armazenamento para uso posterior. Alguns trabalhos já realizaram estudos nesse sentido, indicando resultados promissores pois, em condições de pH próximo à neutralidade, há imobilização desses elementos e não disponibilização para as plantas (Souza et al, 2019). Estudos realizados em áreas de mineração mostraram que houve imobilização de metais tóxicos com aplicação de resíduos do beneficiamento de rochas ornamentais, o que acontece em decorrência da neutralização do pH (Pérez-Sirvent et al, 2007).…”

Is the climate change mitigation effect of enhanced silicate weathering governed by biological processes?

“…Few experiments have tested the effect of silicate additions on macro‐invertebrates and to the best of our knowledge, these experiments have yet been limited to earthworms and rock powders mixed into vermicompost and manure. Divergent responses were reported, with earthworm growth increasing in some cases and decreasing in others, depending on the rock type and amount that was applied (de Souza et al, 2019; Zhu et al, 2013).…”

“…Earthworms can be affected by increased concentrations of, for example, Cu and Ni, especially under conditions of low pH when more cations are desorbed (Ma, 1988; Wang, Xia, et al, 2020), although in general they are fairly tolerant to most heavy metals (Ireland, 1983). Accordingly, de Souza et al (2019) found that the high concentrations of Ni and Cr released during the dissolution of steatite did not hinder earthworm growth.…”

Characteristics of Waste Generated in Dimension Stone Processing

“…Saygili [93], Ibrahim et al [94], Ogila [95], Pastor et al [96], Sabat and Muni [97], Igwe and Adepehin [98], and Sivrikaya et al [99] have shown that the application of stone scrap to stabilise clay soils is beneficial and, at the same time, improves geotechnical properties and reduces soil swelling. The use of fine rock material for fertiliser production, used in agriculture, as well as in the reclamation process, can have a positive impact on the growth of vegetation and improve soil properties [100,[102][103][104][105].…”