Persistence and Factors Affecting Dissipation of Molinate under Flooded Rice Culture1
- L. E. Deuel,
- F. T. Turner,
- K. W. Brown and
- J. D. Price2
Pesticides, essential for the economical production of rice (Oryza sativa L.), could pose a serious problem if transported to surface impoundments and estuaries along the Gulf Coast via the return flow associated with flooded rice culture.
Field experiments were conducted under flooded rice cultivation to determine persistence and half-life of molinate (S-ethyl-hexahydro-1-H-azepine 1-1carbothioate). Persistence and half-life were evaluated with respect to intermittent and continuous flow irrigation schemes at normal and excessive application rates of 3.4 and 11.2 kg/ha molinate, respectively. Persistence at statistically significant levels ranged from 96 to 384 hours following the application, and generally was more a function of the application rate than irrigation scheme. Half-life values averaged 96 ± 22 hours in intermittent flow plots, and 54 ± 17 hours in continuous flow plots over the 3-year experiment. Application rate had little effect on half-life.
Best fit analysis of field data to the first order biological decay equation and laboratory studies under flooded soil conditions suggested that biological degradation was the principle mode by which molinate was dissipated in the field experiment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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