Location: Water Management ResearchTitle: TIF Tarp on emission and fumigant movement in an 8-acre field) Author
Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 9/20/2011
Publication Date: 10/30/2011
Citation: Gao, S., Qin, R., Husein, A., Sullivan, D., Stanghellini, M. 2011. TIF Tarp on emission and fumigant movement in an 8-acre field. International Conference on Methyl Bromide Alternatives and Emissions Reductions. San Deigo, California, October 31-November 2, 2011. p. 21.1-21.3. Interpretive Summary: Low permeability tarps such as the commercial product named totally impermeable film (TIF) have shown their effectiveness in emission reduction from soil fumigation. However, there are issues associated with TIF tarp, including surges in emission following tarp-cutting and emissions at TIF tarped field edges. In collaboration with university, regulatory agency, consulting firm, and the industry, ARS researchers collected fumigant emission and soil data from an 8-acre fumigated field in Lost Hills, CA in June 2011. The field was fumigated with Pic-Clor 60 (40/60 mixture of 1,3-dichloropropene and chloropicrin) in broadcast application. The TIF tarp reduced emissions to as low as 7% and 6% of total applied 1,3-D and chloropicrin, respectively, but damaged tarps could result in much higher emission loss in some local areas. After the tarp was cut 16 days later, a much smaller surge in emission was measured compared to when tarp was cut earlier in other trials. Emission immediately off the tarp-edge on bare soil can be initially high, but the flux diminishes quickly within the distance of 6-feet and with time as well. The information gained from this large field trial is valuable for developing safe practices, policies or regulations on using low permeable tarp in soil fumigation.
Technical Abstract: The use of low permeable film, especially the commercial product named totally impermeable film (TIF), has been found effective in reducing emissions by retaining fumigants under the tarp and in soil. However, there are issues associated with the TIF tarp, including surges in emission following early tarp-cutting and unknown emissions at TIF tarped field edges. Under a collaborative project in an effort to address these issues, a large field trial was conducted in Lost Hills, Kern County, California in June 2011. One 8-acre field was selected to collect data with the following specific objectives: 1) monitor fumigant concentration changes in air under TIF tarp, 2) determine fumigant distribution and changes over time in soil profile in TIF tarped field and monitor movement at tarp edges, and 3) determine emissions from the TIF tarped field and at TIF tarp edges in bare soils. Pic-Clor 60 (40/60 mixture of 1,3-dichloropropene and chloropicrin) was applied at 652.6 kg/ha to 30 cm soil depth with injection nozzles spaced at 25 cm using a Noble plow rig. Emissions were measured with dynamic flux chambers. Air under the tarp and soil gas at various locations and different depths up to 100 cm were sampled throughout the trial. Fumigants were trapped in XAD resin tubes in the field, extracted and analyzed in the laboratory. Over the 16-day tarp covering period, cumulative emission losses as low as 7% 1,3-D and 6% CP of total applied were measured from tarped areas. A much higher emission loss was also detected, which was most likely caused by tarp damages during application because the effectiveness of TIF on emission reduction has been demonstrated in other field trials. Following the tarp-cutting, a much smaller surge in emission was measured compared to previous studies when tarp was cut earlier. Although emission flux measured immediately off the tarp-edge on bare soil was initially an order of magnitude higher than the tarped field, the flux decreased substantially within 2 meter distance and with time as well. The data from this trial are valuable for the development of safe practices, policies and regulations on TIF tarp use.