Location: Application Technology Research
Project Number: 5082-30500-001-073-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 18, 2025
End Date: Sep 17, 2026
Objective:
In this study we propose investigating the potential for detoxifying persistent herbicide residues in irrigation water using ozone. The outcomes will be guidelines for ozone / water exposure times necessary to degrade herbicide residues to concentrations that are not injurious to sensitive crop species. Growers in watershed systems that may be susceptible to this type of herbicide contamination could use these methods to treat water as it is transferred from holding ponds (or other source waters) to the irrigation intake ponds. This would ensure clean and safe irrigation water for crops and avoid catastrophic crop losses. Furthermore, the technologies for detoxification developed herein could be more broadly applied to reduce biotic pests and other organic chemical contaminants (such as PGR’s) that could affect crop growth.
Approach:
To accomplish these goals, a series of experiments will be conducted following these general methods. An ozone treatment system will be provided to cooperator.
Stock solutions of herbicide dilutions will be treated with ozone at different concentrations and time durations. Pre- and post-treatment laboratory analyses and plant bioassays of the water will be conducted. Plant bioassays are critical because several herbicides are biologically active at concentrations below the limit of quantification. Samples of stock and treatment solutions will be sent to an independent laboratory to quantify the herbicide concentrations. Bioassays will follow standardized testing protocols used in our previous research. Bioassay plants will be grown to appropriate size, then treatment solutions applied via foliar drench. Treatment drenches will be applied daily for seven days, then plant responses will be monitored for four weeks. All treatments will be replicated 6 times and the test repeated. Plant responses will be visually evaluated then above-ground biomass measured.
Initial studies to identify effective treatment regimens will be conducted using ‘city’ water. To determine if water quality might impact the optimum ozone treatment regimen, the effective ozone treatment regimens will be further tested with water extracted from a commercial nursery pond. The pond water will be tested with and without particulate filtration prior to ozone treatment.