Soil pH on mobility of imazaquin in oxisols with positive balance of charges
| Autor: | Luís Reynaldo Ferracciú Alleoni, Jussara Borges Regitano, W. S. D. Rocha |
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| Rok vydání: | 2005 |
| Předmět: |
Aqueous solution
Imazaquin Chemical Phenomena Chemistry Chemistry Physical Herbicides Static Electricity Imidazoles Lessivage Sorption Soil science General Chemistry Hydrogen-Ion Concentration chemistry.chemical_compound Soil Oxisol Environmental chemistry Soil pH Soil water Quinolines Leaching (agriculture) General Agricultural and Biological Sciences |
| Zdroj: | Journal of agricultural and food chemistry. 53(10) |
| ISSN: | 0021-8561 |
| Popis: | The influence of soil pH on the leaching potential of the ionizable herbicide imazaquin was assessed on the profile of two highly weathered soils having a net positive charge in the B horizon, in contrast to a soil having a net negative charge in the whole profile, using packed soil column experiments. Imazaquin leached to a large extent and faster at Kd values lower than 1.0 L kg(-1), a much more lenient limit than usually proposed for pesticides in the literature (Kd5.0 L kg(-1)). The amount of imazaquin leached increased with soil pH. As the soil pH increased, the percentage of imazaquin in the anionic forms, the negative surface potential of the soils, as well as imazaquin water solubility also increased, thus reducing sorption because of repulsive electrostatic forces (hydrophilic interactions). For all surface samples (0-0.2 m), imazaquin did not leach at soil pH values lower than pKa (3.8) and more than 80% of the applied amount was leached at pH values higher than 5.5. For subsurface samples from the acric soils, imazaquin only began to leach at soil pH valueszero point of salt effects (ZPSE5.7). In conclusion, the use of surface K(oc) values to predict the amount of imazaquin leached within soil profiles having a positive balance of charges may greatly overestimate its actual leaching potential. |
| Databáze: | OpenAIRE |
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