Ácidos orgânicos e solubilização de fósforo e potássio em biocarvões

• Ano de defesa: 2023
• Autor(a) principal: Siqueira, Camila Barbiero
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Agronomia; Centro de Ciências Agrárias e Engenharias; UFES; Programa de Pós-Graduação em Agronomia
• Palavras-chave em Português: Biochar; Resíduos orgânicos; Teor inorgânico; Agronomia
• Link de acesso: http://repositorio.ufes.br/handle/10/12771

Biochar is considered a tool in the process of transforming waste into potential soil conditioners. Low molecular weight organic acids (AOBPM) interacting with biochar have the ability to solubilize nutrients present in carbonized materials, impacting soil enrichment and consequently reducing the use of chemical fertilizers by updating organic waste. The present work aims to evaluate the total and available P and K contents in coffee straw (PC) and eucalyptus bark (EC) biochars produced under two pyrolysis temperatures, 350 and 600 °C, as well as the solubilization of the inorganic content of these biochars from the addition of AOBPM. The was conducted in the laboratory under a completely randomized experimental design, with three replications per treatment, and three P.A organic acids (acetic, oxalic and citric), in six different concentrations (0; 0.5; 1.0; 1.5; 2 .0 and 2.5 mmol/L). The available P and K contents were determined by extract via colorimetry in a UV-visible spectrophotometer and flame photometry, respectively, total P and K contents through nitroperchloric digestion, and X-ray diffraction analysis of the biochars. There was a difference in solubilization of the inorganic content based on the pyrolysis temperature for the two materials, with PC biochar having higher levels of available P in relation to total P at the pyrolysis temperature of 350 °C, and higher levels of available K in relation to the total K at the pyrolysis temperature of 600 °C. For EC biochar, higher levels were found at a pyrolysis temperature of 600 °C. The presence of organic acids interacting with biochars can cause an increase in the availability of nutrients, such as P and K, with an increase in solubilization in all acids and all doses above 0.5 mmol/L. In our observations, no differential solubilization effect was observed depending on the type of organic acid. The pyrolysis temperature and biochar raw material interferes with the availability of nutrients present in the materials, with the inorganic content being better solubilized at a pyrolysis temperature of 350 °C for PC, and 600 °C for CE. Mechanisms for solubilizing inorganic content in biochars must be stimulated in order to better take advantage of the nutrient source role of phosphorus and potassium in biochars, even if these materials are not applied to the soil with the main objective of functioning as a vehicle for fertilization.