Alternatives to MEBR for California Cropping Systems
Location: Water Management Research
Title: Field evaluation of a new plastic film (Vapor SafeTM) to reduce soil fumigant emission and improve distribution in soil
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2011
Publication Date: April 25, 2011
Citation: Qin, R., Gao, S., Ajwa, H., Sullivan, D., Wang, D., Hanson, B.D. 2011. Field evaluation of a new plastic film (Vapor SafeTM) to reduce soil fumigant emission and improve distribution in soil. Journal of Environmental Quality. 40: 1195-1203.
Interpretive Summary: Low emissions from soil fumigation can provide both environmental benefits and maintain the availability of soil fumigants to important commodity groups such as strawberry growers. Low permeability films have shown potential in achieving low emissions while at the same time improving pest control efficacy by effectively retaining fumigants under the tarp. A new product, the so-called totally impermeable film (TIF), was tested in large field applications in California for its potential to control emissions from shank-applied 1,3-dichloropropene and chloropicrin in comparison with the standard polyethylene (PE) tarp. Results show that TIF can be extremely effective to reduce fumigant emissions compared to PE tarp. Much higher concentrations and more uniform distribution of fumigants were observed under TIF, which can lead to improved efficacy and/or use reduced rates in comparison with the standard PE film. Upon tarp-cutting after a 6-d covering period, however, surges of emissions occurred with much higher emission rates from the TIF-tarped field than the PE-covered field. Thus, a longer waiting period for the tarp-cutting is required to reduce potential exposure risks. This research provides first-hand information on emission reduction using the TIF tarp in large field applications. The information is valuable towards developing feasible practices for the safe use of TIF in soil fumigation.
Preplant soil fumigation is an important pest management practice for strawberry producers in coastal California production regions. However, environmental and human health concerns have resulted in increasingly stringent regulations on fumigant use and have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low permeability film commonly known as “totally impermeable film” (TIF; Vapor SafeTM) on fumigant emissions and distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha-1 in two 0.4 ha field plots in Ventura, CA in fall 2009. One field was sealed with standard polyethylene (PE) film and the other was sealed with TIF following fumigant application. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than the PE field. Total emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d tarp covering period compared to 43% for 1,3-D and 12% for CP from the PE field. However, upon tarp-cutting, the 1,3-D emission surge in the TIF field was much higher due to greater retention than in the PE field, while CP emissions were very low in both fields. Higher concentrations and a more uniform distribution in the soil profile for both 1,3-D and CP were observed under TIF as compared to the PE tarp, suggesting that highly retentive films may allow growers to achieve satisfactory pest control with lower fumigant rates. However, the issue of surging 1,3-D emissions following tarp-cutting could result in potentially high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.