The effect of three levels of moisture (saturation, field capacity, 50% field capacity) and two temperatures (10 and 27 °C) on the extraction of sil applied metoxuron by methanol was determined for an alfisol and a vertisol. Technical grade metoxuron applied at 20 μg g−1 of soil, was extracted by shaking with methanol for 30 min and assayed spectrophotometrically after correcting for soil blanks. There was an initial steep fall in the extractable portion for about 40 to 60 days followed by a much slower decrease in all the cases upto 150 days. The time of 50% extractability of the added herbicide (t50) was lower at 27 °C than at 10 °C, the difference being more marked for the alfisol. The effect of moisture which varied from 40 to 10% for vertisol and 30 to 7.5% for alfisol was not significant. The specific rate of decrease of extractable metoxuron was similar at both temperaturs for the vertisol, and was significantly lower for the alfisol at 10 °C. The observed pattern of the kinetics of methanol available metoxuron is interpeted in terms of an initial rapid partitioning of the herbicide into labile and nonlabile compartments followed by a probable slow release and degradation path. The specific reaction rates for the different steps have been estimated and correlated with other soil properties and their implication on the bioavailability of the herbicide by considering methanol extractability as a suitable index is discussed.
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Raman, S., Chandrasekhar Rao, P. The kinetics of extraction of soil-applied metoxuron by methanol and its biological implications. Water Air Soil Pollut 38, 217–222 (1988). https://doi.org/10.1007/BF00280753
- Soil Property
- Methanol Extractability
- Field Capacity
- Specific Rate