Evaluation of Sedimentation Control as a Best Management Practice for Removing Copper-based Crop Protectants in Plasticulture Runoff
Evaluation of Sedimentation Control as a Best Management Practice for
Removing Copper-based Crop Protectants in Plasticulture Runoff
Karen Marie Stall
The fate and distribution of copper-based crop protectants, applied to tomato fields to
protect against disease, were investigated in a greenhouse-scale simulation of farming
conditions in a coastal environment. Following rainfall, 99% of the applied copper was
found to remain on the fields sorbed to the soil and plants; most of the soil-bound copper
was found sorbed to the top 2.5 centimeters of soil. Of the copper leaving the agricultural
fields, 82% was found in the runoff with the majority, 74%, sorbed to the suspended
solids. The remaining copper, 18%, leached through the soil and entered the groundwater
with 10% in the dissolved phase and 8% sorbed to suspended solids. Although only one-percent
of the copper was found to leave the field, this was sufficient to cause high
copper concentrations (average 2102 Â± 433 mg/L total copper and 189 Â± 139 mg/L
dissolved copper) in the runoff. Copper concentrations in groundwater samples were also
high (average 312 Â± 198 mg/L total copper and 216 Â± 99 mg/L dissolved copper).
Sedimentation, a best management practice for reducing copper loadings, was found to
reduce the total copper concentrations in runoff by 90% to a concentration of 245 Â± 127
mg/L; however, dissolved copper concentrations remained stable, averaging 139 Â± 55
mg/L. Total copper concentrations were significantly reduced by the effective removal of
suspended solids with sorbed copper.
This research was supported by a grant from the Virginia Department of Agriculture and
Consumer Services. Funding was also provided by Sea Grant.