title: Fate of Tebuthiuron and Hexazinone in Green-Cane Harvesting System.
abstract: In Brazil, fire prior to sugar cane harvesting has to be phased out by 2017, but it has already been phased out in up to 85-90% of the cropped area. The new system is called green cane and has entirely changed weed management practices. The main goal of this study was to evaluate the effects of the straw presence as well as humic acid (HA), formulation, soil type, and aging on the sorption and leaching of (14)C-tebuthiuron and hexazinone. Both herbicides presented low sorption for all treatments (Kd,app ≤ 3.25 L kg(-1)), but it was higher for tebuthiuron in the clayer soil (LVd). Straw and aging only slightly enhanced sorption. The HA effects were not clear. Sorption was mostly affected by herbicide and soil type. Straw may promote physical trapping (∼40% of applied amount), which cannot be accessed by "batch" sorption (∼15% of the applied amount is sorbed), attenuating leaching of highly mobile herbicides in green-cane systems. To properly assess leaching through straw residues under laboratory condition, rainfall distribution is very important.
authors.affiliation: Department of Soil Science, University of São Paulo (USP/ESALQ) , Av. Pádua Dias 11, 13418-260 Piracicaba (SP), Brazil.
authors.forename: Thiago Antônio Pinheiro
authors.initials: TA
authors.lastname: Toniêto
authors.affiliation: Department of Soil Science, University of São Paulo (USP/ESALQ) , Av. Pádua Dias 11, 13418-260 Piracicaba (SP), Brazil.
authors.forename: Letícia
authors.initials: L
authors.lastname: de Pierri
authors.affiliation: Laboratory of Ecotoxicology, University of São Paulo (USP/CENA) , Av. Centenário 303, 13400-970 Piracicaba (SP), Brazil.
authors.forename: Valdemar Luiz
authors.initials: VL
authors.lastname: Tornisielo
authors.affiliation: Department of Soil Science, University of São Paulo (USP/ESALQ) , Av. Pádua Dias 11, 13418-260 Piracicaba (SP), Brazil.
authors.forename: Jussara Borges
authors.initials: JB
authors.lastname: Regitano
mesh_terms: D000327:Adsorption; D001938:Brazil; D004784:Environmental Monitoring; D006540:Herbicides / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D007700:Kinetics; D008782:Methylurea Compounds / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry* / Q000254:growth & development; D031786:Saccharum / Q000737:chemistry / Q000254:growth & development; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D014227:Triazines / Q000737:chemistry*
chemical_list: D006540:Herbicides; D006812:Humic Substances; D008782:Methylurea Compounds; D012987:Soil; D012989:Soil Pollutants; D014227:Triazines; C010346:tebuthiuron; C025641:hexazinone
keywords: fire; groundwater pollution; humic acid; mobility; pesticides; straw