Sorção, dessorção, lixiviação e meia-vida do diuron em quatro latossolos brasileiros

• Ano de defesa: 2011
• Autor(a) principal: Rocha, Paulo Roberto Ribeiro
• Orientador(a): Silva, Antônio Alberto da
• Banca de defesa: Ferreira, Evander Alves , Silva, Leandra de Oliveira Cruz da , Ferreira, Francisco Affonso
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitotecnia
• Departamento: Plantas daninhas, Alelopatia, Herbicidas e Resíduos; Fisiologia de culturas; Manejo pós-colheita de
• País: BR
• Palavras-chave em Português: Herbicidas; Latossolos
• Palavras-chave em Inglês: Herbicides; Latosols
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1167

The knowledge of the behavior of herbicides in soil is crucial to secure recommendations from the standpoint of technical and environmental. In this work, the sorption, desorption, leaching, and half-life of diuron in Red-Yellow Latosol (LVA), Red Latosol (LV), and Yellow Latosol (LA), with different pH values, were evaluated using bioassays and high performance liquid chromatography (HPLC). Sorption and desorption of diuron were determined by "Batch Equilibrium" method. PVC columns filled with soils and sectioned at different depths (0-5, 5-10, 10-15, 15-20, 20-25, 25-30 cm) were used for the diuron leaching study. After the diuron application in the top of the columns, 60 mm of rain, for 4 hours, were simulated. Subsequently, they were opened longitudinally to collected soil samples to quantify the herbicides using HPLC and to seed bioindicator plant (Cucumis sativus). Intoxication and dry matter of plants were evaluated 21 days after the emergence. To determine the persistence of diuron, the herbicide applying was made in pots containing different soils. In these pots, soil samples were collected for quantification of the herbicide and the bioindicator plant was seed at 1, 8, 15, 22, 36, 66, 96, and 156 days after application. The intoxication and dry matter of plants were evaluated 21 days after the emergence. The soils with higher organic matter content, LVA and LVAh showed higher sorption coefficients. The diuron desorption process was the inverse of the diuron sorption. The diuron downward movement was higher in the LV, that is a sandy soil and has less organic matter. The pH rise increased theherbicide concentration in the surface layers of the soil with increased sorption. The bioassay was effective todetect the presence of diuron, even in deeper layers of the LVA pH 5.9, LV pH 5.0, LV pH 6.2, and LA pH 6.3, where there were low herbicide concentrations. The half-life values of diuron were estimatedin 40, 46, 89, 90, and 91 days respectively for LV pH 6,2, LA pH 6,3, LV pH 5,0, LVA pH 5,9, and LVA pH 5,0. The sorption, desorption, leaching, and half-life of diuron are influenced by physical and chemical characteristics of soils. Higher content of organic matter in soils favors the sorption and persistence (half-life) and discourages leaching and desorption of diuron. Applications of diuron in sandy soils with low organic matter content represent a high risk, mainly in soils with shallower groundwater.