We have developed metolachlor controlled-release formulations (CRF) based on its solubilization in micelles and adsorption to clay. This study aims to test the effect of soil wetting and drying cycles (WDCs) on metolachlor fate applied as commercial and as CRFs. Surprisingly, metolachlor release from the soil subjected to WDCs was higher than its release from the untreated soil. This was attributed to soil aggregation, higher in untreated soils, which trapped the herbicide and reduced its release. Metolachlor leaching from the commercial product through a thin soil layer was high and increased with WDCs while its leaching from the CRF was moderate, even when subject to WDCs. A bioassay in soil columns demonstrated good weed control and reduced leaching for the CRF in comparison with the commercial formulation, even after four WDCs. These results emphasize the advantage of the CRF over the commercial formulation even when the soil is subjected to WDCs.

Effect of soil wetting and drying cycles on metolachlor fate when applied as commercial and as controlled-release formulations

244th National Meeting (2012)

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