Microencapsulated and Conventional Clomazone Formulations: Dynamics in Soil, Crop Residue, and Soybean

Clomazone is widely used in no-tillage systems, where volatilization and leaching can reduce its effectiveness. Microencapsulation has been proposed to improve herbicide stability and persistence. This study evaluated the behavior of two microencapsulated (ME) and two emulsifiable concentrate (EC) commercial clomazone formulations under controlled conditions in soil, corn residue, and soybean plants. In soil, the evaluated ME formulations showed low initial leaching but a gradual increase over time, reaching 42.3% (ME-1) and 36.9% (ME-2) at 30 days after application (DAA). In contrast, the EC formulations exhibited high initial leaching at 1 DAA (22% for EC-1 and 20% for EC-2), followed by lower cumulative losses than those observed for the ME formulations. In corn residue, clomazone recovery was higher for the ME formulations (40.8 μg for ME-1 and 27.6 μg for ME-2) compared with the EC formulations (11.5 μg for EC-2 and 5.8 μg for EC-1). In soybean plants, the ME formulations retained more than 90% of clomazone on the leaf surface, with 78-86% remaining encapsulated, whereas the EC formulations showed higher internal absorption (up to 69%). No significant phytotoxicity was observed in soybean for any formulation. Overall, the evaluated ME formulations modified the environmental fate of clomazone and plant exposure pathways compared to the tested EC formulations. These results indicate differences in environmental behavior and crop selectivity in no-tillage systems but are limited to the clomazone formulations evaluated.