HR: 0830h
AN: H41E-1043    [PDF]
TI: Effectiveness of Vegetated Buffer Strips in Reducing Dormant Season Orthophosphate Pesticide Loading to Surface Waters in Glenn County, Northern California
AU: * GIlbert, K D
EM: kdgilbert@animail.net
AF: Dept. of Geological & Environmental Sciences, CSU, Chico, Chico, CA 95929-0205 United States
AU: Brown, D L
EM: dlbrown@csuchico.edu
AF: Dept. of Geological & Environmental Sciences, CSU, Chico, Chico, CA 95929-0205 United States
AU: Altier, L
EM: laltier@csuchico.edu
AF: College of Agriculture, CSU, Chico, Chico, CA 95929-0310 United States
AU: Oliver, M N
EM: mnoliver@ucdavis.edu
AF: UC Cooperative Extension, UC Davis, Davis, CA 95616 United States
AB: Riparian buffer strips are used in preventing nonpoint source contamination of agricultural runoff. The design and effectiveness of buffers varies widely under differing environmental conditions. Over the past two years, a project was implemented to evaluate the effectiveness of certain Best Management Practices in reducing organophosphate (OP) pesticide transport from almond orchards to local surface waters in Glenn County, northern California. Diazinon is a commonly-used OP pesticide applied during the dormant season in almond and stone-fruit orchards throughout the California Central Valley. Dormant season diazinon application coincides with the months of greatest rainfall and surface runoff in California. Three filter strip treatments were established: one planted with native vegetation, one with weedy resident vegetation, and the third with a bare soil surface. As a demonstration and reconnaissance project, replication of the treatments in this study was lacking (one plot of each vegetation type and two bare ground plots). Diazinon was applied in test orchard cells in January 2003. Surface runoff, shallow groundwater in the root zone, and deeper groundwater were monitored for the transport of diazinon during the three subsequent storm events. Composite surface water samples and flow volumes were obtained for each storm event using automated surface water collectors. Runoff and infiltration results indicate greater infiltration occurred in the vegetated plots as would be expected. Infiltration on bare ground plots was approximately 25%-50% less than on the vegetated plots. However, differences between the two vegetated plot treatments were less than 5%. Diazinon concentrations were reduced as surface runoff crossed the buffer strips for all three treatments. Detectable levels of diazinon were still present in runoff following the third storm, seven weeks after the pesticide application. Further replicated studies are currently being prepared for the coming dormant season and this study will continue over the next three years.
DE: 1803 Anthropogenic effects
DE: 1831 Groundwater quality
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2003 Fall Meeting