title: Organomineral Interactions and Herbicide Sorption in Brazilian Tropical and Subtropical Oxisols under No-Tillage.
abstract: We evaluated the effects of the soil organic matter (SOM) composition, distribution between soil aggregates size, and their interactions with the mineral phase on herbicide sorption (alachlor, bentazon, and imazethapyr) in tropical and subtropical Oxisols under no-till systems (NT). Using soil physical fractionation approach, sorption experiments were performed on whole soils and their aggregates. SOM chemistry was assessed by CP/MAS (13)C NMR. The lower sorption observed in tropical soils was attributed to the greater blockage of SOM sorption sites than in subtropical soils. When these sites were exposed upon physical fractionation, sorption of the three herbicides in tropical soils increased, especially for imazethapyr. High amounts of poorly crystallized sesquioxides in these soils may have contributed to masking of sorption sites, indicating that organomineral interactions may lead to blockage of sorption sites on SOM in tropical soils.
authors.affiliation: Department of Soils and Agricultural Engineering, Federal University of Paraná , Rua dos Funcionários 1540, Curitiba, Paraná, Brazil.
authors.forename: Eloana J
authors.initials: EJ
authors.lastname: Bonfleur
authors.affiliation: CSIRO Land and Water, Waite Campus, PMB No. 2, Glen Osmond, South Australia 5064, Australia.
authors.forename: Rai S
authors.initials: RS
authors.lastname: Kookana
authors.affiliation: Center of Nuclear Energy in Agriculture (CENA). Ecotoxicology Laboratory, University of São Paulo (USP) , Piracicaba, São Paulo, Brazil.
authors.forename: Valdemar L
authors.initials: VL
authors.lastname: Tornisielo
authors.affiliation: "Luiz de Queiroz" College of Agriculture, Soil Science Department, University of São Paulo , Avenida Pádua Dias 11, Piracicaba, São Paulo, Brazil.
authors.forename: Jussara B
authors.initials: JB
authors.lastname: Regitano
mesh_terms: D000081:Acetamides / Q000737:chemistry; D000383:Agriculture; D001938:Brazil; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D008903:Minerals / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D000081:Acetamides; D006540:Herbicides; D008903:Minerals; D009930:Organic Chemicals; D012987:Soil; D012989:Soil Pollutants; C000188:alachlor
keywords: CP/MAS 13C NMR; alachlor; aluminum oxides; bentazon; imazethapyr; iron oxides; organic matter quality; soil physical fractionation