|NORBERG, KRISTIN - UNIVERSITY OF MINNESOTA
Submitted to: Minnesota Academy of Science Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/6/1996
Publication Date: N/A
Technical Abstract: Sorption studies are important for determining a herbicide's persistence, mobility and plant availability in soils. Sorption data is lacking on the newly-developed sulfonylurea group of herbicides. Laboratory studies were conducted to determine the sorption and desorption of metsulfuron-methyl on a clay loam soil. Sorption studies were conducted using the batch equilibration method: in brief, soil samples were spiked with four different concentrations of **14C metsulfuron-methyl, shaken for different time intervals, centrifuged, and solutions were analyzed by liquid scintillation counting. Desorption was determined on the same samples after sorption using 0.01N CaC12. Kinetic studies indicate that sorption equilibrium is achieved after a 12-hour period. Sorption data were fitted to the Freundlich equation. The Freundlich K value was low, 1.71, indicating a high potential mobility. Herbicides with low sorption and high mobility can leach and cause ground water pollution if their degradation times are sufficiently long. Desorption results indicate that the metsulfuron-methyl that is sorbed, however, will not desorb. It appears from this research that ground water pollution could occur if the degradation time of metsulfuron-methyl is long. Therefore, additional studies on degradation are necessary to fully predict the environmental impact of metsulfuron-methyl in this soil.