Biochar application in soil: behavior and toxicity

• Autor(a) principal: Jahanianfard, Dina
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/28947
• topic: Biochar; Scientometry; Sludge-derived; Incubation; Phytotoxicity; Germination test; Growth test

The biochar is a by-product produced from the pyrolyzing an organic feedstock, mainly biomass, through a thermochemical process with limited or without the presence of oxygen. The application of biochar goes back to approximately 2000 years ago knowing that it was practiced mainly in ancient Amazonia. In order to determine the growth of the science in the area of the biochar application as a soil additive, a scientometric study was performed in the Web of Science core collection with the advance search of some specific keywords and the total number of 2123 English documents were retrieved published from 2000 to 2018. These bibliographic records were then analyzed regarding some scientometric criteria such as publication type, publication year, contributing country, keyword analysis, author analysis, cited authors, cited journals, categories, and cited documents. The obtained results in this regard demonstrated that despite many research performed in this field, the need regarding more collaboration among the researchers globally and overcoming matters regarding the proper feedstock, pyrolysis condition, and toxic behavior of the biochar is still greatly felt in order to commercialize the biochar application as a soil amendment. Moreover, as a case study, one type of biochar was pyrolyzed from the secondary sludge of the wastewater treatment of pulp and paper mill industry. Further, the produced biochar was analyzed regarding its chemical and physical characteristics. The performed analysis revealed that the biochar was porous and possesses an irregular microstructure. Also, it was in high pH and electric conductivity. Further on, an incubation test was conducted on the soil incubated with biochar as the additive. To provide a comparison, a liming agent was also applied in different soil samples. The amended soil samples with the liming agent were also kept in the incubation. Thereafter the incubation period, which was 21 days, it was observed that the biochar has the capacity to alter the pH, electrical conductivity, and the water holding capacity of the soil while with the liming agent only the pH increased significantly and no considerable modifications were observed in the other measured parameters. Furthermore, a phytotoxicity analysis regarding the germination of the seeds and their growth was conducted via the application of Lepidium sativum seeds (for germination test) and Lolium perenne seeds (for growth test). The obtained results in this regard demonstrated the non-toxic effect of the biochar addition on the seed germination. Also, thereafter the conduction of the growth test, it was observed that the biochar with the corresponding dose of 2.5% w/w enhanced the crop yield significantly in comparison to the collected soil via providing the crops with more dry-weight and height. While the crop obtained from the amended soil with the biochar higher doses had a negative effect on the crop yield. The liming agent did not significantly increase the crop yield as well. However, more research regarding the potentially toxic elements uptake by plants grown in the amended soil with biochar is considered to be crucial for a safe application of such an amendment.