AGRO 4 |
| The leaching of imidacloprid, 1-((6-chloro-3-pyridinyl)-methyl)-4,5-dihydro-N-nitro-1H-imidazole-2-amine, was studied in three types of soil viz. sandy, sandy loam, and clayey soil varying in soil pH, organic carbon, and clay content. Imidacloprid is a polar molecule (Log Pow = 0.57) with high water solubility 510 mg/L. Imidacloprid is a hydrolytically stable insecticide but more rapidly photodegraded in water (hours) than in soil (months). A leaching experiment was carried out in a packed column (35 x 6 cm) with soil up to 25 cm. Treated soil (10 gm soil + 1000 mg imidacloprid) was spread at top. A constant head of 2 cm water was maintained. Five fractions of 500 mL leachate were collected. The total 2.5 L simulates 88 cm of rainfall. The soil core was pushed down and sliced into 5 cores of 5 cm each. A major portion was found in top 0-5 cm soil layer. Imidacloprid recovered in 0-5 cm layer was 96, 97, and 99% in sandy, sandy loam, and clayey soil, respectively. Imidacloprid leached down 10-15 cm core in sandy soil while in others it remained till 10 cm core. Only 0.2-4.0% imidacloprid was recovered in leachate of 3 different soil types. Leaching was highest in sandy soil followed by sandy loam and clayey soil. The trend in leaching could be explained on the basis of organic matter and clay content. |
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Agrochemical Residue & Metabolism Chemistry
8:30 AM-11:30 AM, Sunday, 10 September 2006 San Francisco Marriott -- Salon 1, Oral
Division of Agrochemicals |