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Wu C.,Southwest University | Wu C.,Institute of the Control of Agrochemical of Sichuan Province | Wu C.,Ganzi Research Institute of Agricultural Science | Zhang S.,Sichuan Agricultural University | And 3 more authors.
Journal of Environmental Sciences | Year: 2011

Monosulfuron-ester is a new, low rate, sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed control; however, there is a lack of published information on its behavior in soils. The adsorption and desorption of monosulfuron-ester by seven type soils were measured using a batch equilibrium technique. The results showed that the Freundlich equation fitted its adsorption and desorption well, and the Freundlich constant values (AT f-ads) ranged from 0.88 to 5.66. Adsorption isotherms were nonlinear with 1/n f-ads values < 1. Soil pH, organic matter (OM), and clay content were the main factors influencing its adsorption and desorption. Adsorption and desorption were negatively correlated with pH 4.0-8.0 while positively correlated with OM and clay content. The adsorption of monosulfuron-ester was mainly a physical process, because its free energy (ΔG) in seven soils was less than 40 kJ/mol. Monosulfuron-ester adsorption by three soils increased with increasing CaCl 2 concentration using CaCl 2 as a background electrolyte. Monosulfuron-ester desorption was hysteretic in all tested soils. © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.

Wu C.-X.,Southwest University | Wu C.-X.,Institute of the Control of Agrochemical of Sichuan Province | Nie G.,Institute of the Control of Agrochemical of Sichuan Province | Zhang Z.-M.,Institute of the Control of Agrochemical of Sichuan Province | And 3 more authors.
Journal of Integrative Agriculture | Year: 2013

Methiopyrisulfuron is a novel sulfonylurea herbicide with good activity for annual broadleaf and gramineal weeds control. Present study was to investigate the effects of organic amendments (including peat (PE), sewage sludge (SS), and humic acid (HA)) on adsorption, desorption and leaching of methiopyrisulfuron in soils. The batch equilibration technique was applied for adsorption-desorption experiments and the leaching was tested through soil column simulated experiments under laboratory conditions. The Freundlich model may well describe adsorption-desorption of methiopyrisulfuron on organic amendments, the natural soil, and amended soils. Organic amendments could not only greatly increase the adsorption capacity of methiopyrisulfuron, but also significantly enhance the hysteresis of desorption of methiopyrisulfuron. The correlations between Kf-ads and organic matter content of amended soils were significant, and the correlations between H and soil organic matter in amended soils with PE, SS, and HA were significant too. The results of soil column experiments indicated that organic amendments greatly decreased leaching of methiopyrisulfuron. This study suggested that PE, SS, and HA could greatly influence environmental behavior of methiopyrisulfuron in soils. Use of organic amendments might be an effective management practice for controlling potential pollution of methiopyrisulfuron to environment. © 2013 Chinese Academy of Agricultural Sciences.

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