Comportamento do fomesafen em solos brasileiros

• Autor(a) principal: Silva, Gustavo Rodrigues da
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4599
• topic: Bioensaio; Carryover; Impacto ambiental; Lixiviação; Características do solo; Bioassay; Carryover; Environmental impact; Leaching; Soil caracteristics; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The sorption and leaching of fomesafen were evaluated in soils with different physicochemical characteristics and its persistence in a Red-Yellow Latosol cultivated with common bean in no-tillage and conventional system. The first experiment evaluated the sorption process of the fomesafen in Ultisol, Cambisol and Histosol. Besides soil, washed sand was used as an inert material for determination of the sorption ratio of fomesafen in the soil. The bioassay method was applied, using Sorghum vulgare plants as bio-indicator of herbicide presence. Plant poisoning evaluation and harvest for dry matter determination were carried out 21 days after sorghum sowing. To calculate C50, the nonlinear log-logistic model was applied and sorption ratios of the herbicide were obtained in different soils. In the second experiment it was evaluated the leaching of fomesafen in four soils: Inceptisol, Latosol with pH corrected and original, Ultisol and Histosol. To this end, we used bioassays employing the hybrid sorghum plant BRS655 as indicative of the presence of fomesafen in soils. The soils were packed in PVC columns of 10 cm diameter and 50 cm in length, marked and sectioned every 5 cm away. Was applied fomesafen at the top of the columns, at a dose of 500 g ha-1 of fomesafen. 12 hours after proceeded we simulated rainfall applying a level of water of 80 mm. Evaluations were performed poisoning plant and harvest for determination of shoot dry matter at 21 days after planting sorghum in the soil of each column. The objective of third experiment was to evaluate the persistence of fomesafen in Red-Yellow Ultisol cultivated with common bean in notillage and conventional systems, featuring two separate experiments. The experimental design was a randomized block with four replications arranged in a split plot, where the plots represent the herbicide doses (0.0, 125, 250, 500 g ha-1) and subplots ages of soil collected (15, 30, 45, 60, 75, 90, 105, 120, 135 and 150 days after herbicide application). Soil samples were collected from 15 to 15 days, in central interrows of the plots and transferred to plastic pots of 280 cm3, which was seeded sorghum as a biological indicator of the presence of fomesafen. At 21 days after emergence was evaluated poisoning of plants, on a scale where 0 (zero) representing the complete absence of symptoms and 100, death of the plant. The content of organic matter and clay of soils were the attributes that more influenced the sorption of fomesafen. Their leaching was more affected, in descending order of importance by organic matter content, texture and pH of the soil and its persistence by dose of fomesafen and plantation system.