Management of agricultural pesticide rinsate using a biobed under Manitoba conditions

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Johnson, Sarah
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A dual-celled biobed was built at the Ian Morrison N. Research farm in Carman, MB to degrade and retain the pesticides from pesticide rinsate derived at the farm. The biobed was designed for Manitoba conditions with considerations taken from existing biobeds in the Province of Saskatchewan. Temperature and moisture of the biomixture contained within the biobed was monitored using probes for the duration of the study. Three pesticides (2,4-DB, dicamba, and metrafenone) were detected in the biomixture prior to pesticide input from rinsing in 2020 but had degraded by the end of the season and were no longer detected. The Influent of the biobed was analyzed for a suite of pesticides and 23 pesticides and one pesticide metabolite were detected. In Effluent One only 11 of the 24 compounds were detected, and six compounds were detected in Effluent Two. Total pesticide concentrations significantly decreased for Influent > Effluent One > Effluent Two. Pesticides detected in the effluents tended to have higher GUS or Koc values. In 2021, a large influx of prepared spraying liquid containing glufosinate (approximately 680L) overburdened the biobed and resulted in reduced degradation and increasing mean concentrations from Influent > Effluent One > Effluent Two. Glufosinate and seven other pesticides detected in the influent were not measured in biomix due to method limitations. There were three pesticides (bifenthrin, trifloxystrobin, and diuron) detected in the biomixture samples in 2021, and only diuron, which had the highest GUS and Koc values, was still detected at the end of the season.
biobed, dual-cell, single-cell, pesticide, pesticide rinsate, rinsate management system, rinsate management, biomixture