Alleviation of aluminum and cadmium toxicity by biochar and its potential toxicity to sorghum

Abstract

Highlights:Use of biochar to mitigate soils contaminated by trace elements. Pyrolysis as an alternative to sewage sludge disposal in the environment. Some mechanisms involved in the alleviation of soil acidity by biochar. A rapid and simple test to assess biochar toxicity. Biochar as a strong and effective sorbent for aluminum and cadmium. AbstractBiochar has been used as an alternative in organic wastes management and to alleviate trace elements toxicity. The aim of this research was to use a rapid and simple test to detect the potential toxic effects of biochar and its ability to alleviate aluminum and cadmium toxicity to seeds and seedlings of Sorghum bicolor L. Two experiments were carried out in Petri dishes with two different biochars where sorghum seeds were exposed to aluminum (experiment 1) and cadmium (experiment 2) solutions. The experimental designs were completely randomized, with five doses of aluminum or cadmium in aqueous solution (0, 0.5, 1, 2, and 4 mmol/L of Al or Cd), combined with or without the addition of 0.25 g of biochar from sugarcane bagasse or from sewage sludge. Compared to treatments without biochar, in the treatments with biochar, higher seed germination rate and growth of sorghum seedlings were obtained. Moreover, the biochars were not toxic to sorghum and they decreased the toxicity of aluminum and cadmium, mainly the biochar from sewage sludge that presented higher pH and greater occurrence of functional groups in its particles. ResumoO biochar tem sido utilizado como uma alternativa para o manejo de resíduos orgânicos e na remedição da toxidez por elementos traços. Objetivou-se com essa pesquisa usar um teste rápido e simples para detectar os potenciais efeitos tóxicos do biochar e sua capacidade de minimizar a toxidez por alumínio e cádmio para sementes e plântulas de Sorghum bicolor L. Conduziu-se dois experimentos em placas de Semina: Ciências Agrárias, Londrina, v. 41, n. 1, p. 95-108, jan./fev. 2020 Almeida, J. B. et al.Petri com dois diferentes biochars onde as sementes de sorgo foram expostas às soluções de alumínio (experimento 1) e cádmio (experimento 2). Os delineamentos experimentais foram inteiramente casualizados, com cinco doses de alumínio ou cádmio na solução aquosa (0, 0,5, 1, 2 e 4 mmol L-1 de Al ou Cd), combinados com ou sem a adição de 0,25g de biochar de bagaço de cana-de-açúcar (BB) ou de lodo de esgoto (BS). Nos tratamentos com biochar, obtém-se maior percentagem de germinação de sementes e crescimento de plântulas de sorgo em relação a ausência de biochar. Além disso, os biochars não são tóxicos para o sorgo e minimizam a toxicidade por alumínio e cádmio, principalmente o BS que apresenta maior pH e maior ocorrência de grupos funcionais em suas partículas. Palavras-chave: Sorghum bicolor. Elementos traços. Acidez do solo. Pirólise. Resíduos orgânicos.

Biochar as an alternative to improve the in vitro environment for Pitaya (Hylocereus undatus Haw) and strawberry (Fragaria x ananassa Duch) growing

“…However, the lower root dry mass yield can be attributed to the immobilization of silver ions (Ag + ) by biochar. In general, due to ash content, rich in alkali metal oxides and hydroxides (De Almeida et al, 2020), biochars raise the medium's pH, and, consequently, precipitation of cationic metal ions can occur (Rajapaksha et al, 2016;Rizwan et al, 2016). Besides, biochars are very efficient adsorbents of cationic metal ions due to the high surface area, particle porosity, and functional groups that exhibit negative electric charges (Bian et al, 2014;Lu et al, 2014;Tang et al, 2013).…”

Biochar as a soil conditioner for common bean plants

“…As the soil pH increases due to biochar, Al 3+ is converted to Al(OH) 2+ , Al(OH) 2 + , and Al(OH) 3 , reducing the toxicity of aluminum to plants (Qian, Chen, & Hu, 2013;Tang et al, 2013). In addition to increasing soil pH, biochar can strongly adsorb the monomers Al(OH) 2+ and Al(OH) 2 + (Almeida et al, 2020), because of its high aromaticity and specific surface area (Qian et al, 2013).…”

“…Various studies have shown the potential of biochar to neutralize soil acidity and increase soil phosphorus (P) content (Almeida et al, 2020;Alves et al, 2021). However, there are few studies on the effects of the interaction between biochar, liming, and phosphate fertilization on soil fertility and plant productivity.…”