Pesticide leaching potential assessment in multilayered soils.

• Autor(a) principal: SPADOTTO, C. A.
• Data de Publicação: 2002
• Outros Autores: GOMES, M. A. F., HORNSBY, A. G.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/15045
• topic: Agrotóxico; Lixiviação

The Attenuation Factor ( AF) model generalized for multilayered soils was used to estimate the leaching potentials of non-ionic and non-ionizable pesticides in Brazilian soils. The model applied takes into account pesticide and soil properties, as well as the net recharge rate. Advective transport of pesticides and piston water flow, instantaneous equilibrium between phases in soil, and first-order pesticide degradation were assumed. The highest overall leaching potential pesticides were Tebuthiuron and Hexazinone, which present half-life ( t½) values exceeding 90 days and sorption coefficient ( Koc) less than 80 mL/g. For all of the pesticides in the three soils, the percent of the pesticide entering at the top of each layer that exits, the bottom of that layer increased with depth because of the decrease in the pesticide travel time ( tr), which is, in turn, due to the lower retardation factor ( RF). In a Typic Quartzipsamment soil, the shortest water travel time values, due to the lowest field capacity ( FC) values, resulted in the highest AF values and leaching potential. Results allow estimating that about 54% of Tebuthiuron and 13% of Hexazinone that reaches the soil surface would pass through the top 120 cm of the Typic Quartzipsamment.