Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2011
Publication Date: 11/1/2011
Citation: Alonso, D.G., Koskinen, W.C., Oliveira, R.S., Constantin, J., Mislankar, S. 2011. Sorption-desorption of indaziflam in selected agricultural soils. Journal of Agricultural and Food Chemistry. 59(24):13096-13101. Interpretive Summary: Indaziflam is a new herbicide active ingredient, classified as a member of the new chemical class “alkylazine”. It is used at very low rates of active ingredient and controls many annual grasses broadleaf weeds. In spite of the low application rates, it appears that it has long residual activity for most proposed uses. Like other preemergence herbicides applied to soil, it is necessary to understand the fate and behavior of this herbicide in the soil system and, consequently, the potential risk of contamination of water resources. This study was aimed at characterizing the sorption and desorption coefficients of indaziflam in soils from tropical and glacial regions. Sorption and desorption, or binding and release, of indaziflam in 6 soils from Brazil and 3 soils from the USA, with different physical chemical properties, were investigated using the batch equilibration method.The results suggest that indaziflam potential mobility would range from moderate to low in soil considering its sorption coefficients. Indaziflam was not readily desorbed from soil, further decreasing its potential mobility for offsite transport. These data are the first published data on indaziflam sorption-desorption in soil. However, for scientists to better evaluate potential mobility, information is needed on aminocyclopyrachlor degradation and sorption of aged residues.
Technical Abstract: Sorption and desorption of indaziflam in 6 soils from Brazil and 3 soils from the USA, with different physical chemical properties, were investigated using the batch equilibration method. Sorption kinetics demonstrated that soil-solution equilibrium was attained in a 24-h period. The Freundlich equation described the sorption behavior of the herbicide for all soils (R2 > 0.99). Kf values of the tropical soils ranged from 4.66 to 29.3 and 1/n values were > 0.95. Sorption was positively correlated to % OC and clay contents. Glacial soil Kf values ranged from 6.62 to 14.3; 1/n values for sorption were > 0.92. Kf values from glacial soils was also positively correlated with % OC, but were negatively correlated with soil pH and % clay. The results suggest that indaziflam potential mobility would range from moderate to low in soil considering its sorption coefficients. Desorption was hysteretic on all soils further decreasing its potential mobility for offsite transport.