Leaching and half-life of the herbicide tebuthiuron on a recharge area of Guarany aquifer in sugarcane fields in Brazil

• Published in: Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes Pesticides, food contaminants, and agricultural wastes, 2007-08, Vol.42 (6), p.635-639
• Main Authors: Cerdeira, A.L, Desouza, M.D, Queiroz, S.C.N, Ferracini, V.L, Bolonhezi, D, Gomes, M.A.F, Rosa, M.A, Balderrama, O, Rampazzo, P, Queiroz, R.H.C
• Format: Article
• Language: English
• Subjects: agricultural soils; agricultural watersheds; Agronomy. Soil science and plant productions; application timing; aquifers; Biological and medical sciences; Brazil; cities; degradation; Environmental Monitoring - methods; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; ground water; groundwater contamination; Half-Life; herbicide residues; Herbicides - analysis; Herbicides - chemistry; leaching; Methylurea Compounds - analysis; Methylurea Compounds - chemistry; nonpoint source pollution; Risk Assessment; Saccharum - chemistry; Saccharum officinarum; sandy soils; Soil and water pollution; soil depth; Soil Pollutants - analysis; soil pollution; Soil science; soil water recharge; Solubility; solute transport; sugarcane; Tebuthiuron; Water Movements; Water Pollutants, Chemical - analysis; Water Pollution, Chemical - analysis; Water Pollution, Chemical - prevention & control; water quality; Water Supply - standards; wells
• ISSN: 0360-1234; 1532-4109
• DOI: 10.1080/03601230701465593

This study was undertaken to evaluate the degradation and mobility of the herbicide tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea) in soil under field conditions, and its potential for leaching and groundwater contamination. A watershed, Espraiado, located over a recharge area in Brazil, was chosen for soil and water studies. At Espraiado, water samples were collected from seven wells at intervals of three months from March 2004 to June 2006 and analyzed for tebuthiuron. Other samples were taken from city wells located outside of the recharge area. To assess the potential movement to the aquifer, tebuthiuron was also applied to trial plots at the recommended label rate of 1.0 kg/ha a.i. in May of 2004, with and without sugarcane coverage, on sandy soil. Soil samples were collected during the years of 2004 and 2005, at depths intervals of 20 cm from soil surface down to 120 cm and analyzed for tebuthiuron at zero, 3, 30, 60, 90, 120, 150, 180, 240, and 300 days after application. There was no clear effect of sugarcane coverage on the tebuthiuron degradation in soils, but it moved faster into the soil where there was no cover. After 180 days there were no measurable residues in the soil, and tebuthiuron was not found below 40 cm depth in any time. Tebuthiuron had a half-life of 20 days under those conditions. No tebuthiuron residue was found in ground water samples at any sampling time.