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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #345517
Research Project: Develop Water Management Strategies to Sustain Water Productivity and Protect Water Quality in Irrigated Agriculture

Location: Water Management Research

Title: Deep injection and the potential of biochar to reduce fumigant emissions and effects on nematode control

Author
item Gao, Suduan
item DOLL, DAVID - University Of California
item STANGHELLINI, MIKE - Trical Inc
item WESTERDAHL, BECKY - University Of California
item Wang, Dong
item HANSON, BRAD - University Of California

Submitted to: Journal of Environmental Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2018
Publication Date: 6/10/2018
Citation: Gao, S., Doll, D.A., Stanghellini, M.S., Westerdahl, B.B., Wang, D., Hanson, B.D. 2018. Deep injection and the potential of biochar to reduce fumigant emissions and effects on nematode control. Journal of Environmental Engineering. 223:469-477.

Interpretive Summary: Soil fumigation is used to control nematodes and other pests before replanting orchards. Low permeability tarps are used to effectively reduce fumigant emissions after soil fumigation, but the costs are high and disposal of tarps after use is required. This research in an almond orchard, evaluated whether deep fumigant injection and biochar soil amendments can reduce emissions, improve fumigant distribution in soil, and provide acceptable control of plant parasitic nematodes. Data showed that deep injection to 65 cm soil depth enhanced fumigant movement to below 60 cm that the regular injection at 45 cm depth could not deliver, and also resulted in significantly lower emissions. Biochar amendment at 40 ton/ha had the lowest emission among all treatments, more effectively reduced emission than a low permeability film, and did not negatively impact nematode control. This research illustrated the potential of using biochar to mitigate fumigant emissions, but more cost effective materials from local orchard feedstock are needed.

Technical Abstract: Reducing emissions is essential for minimizing the environmental impacts of pre-plant soil fumigation. Low permeability plastic films are effective at reducing emissions but have high initial purchase, installation, and disposal costs. The objective of this study was to evaluate if deep fumigant injection and biochar soil amendments can reduce emissions, improve fumigant distribution in soil, and provide acceptable control of plant parasitic nematodes. A pre-plant soil fumigation trial was conducted in a commercial orchard in the San Joaquin Valley, CA, USA. Treatments included two rates of Telone® C-35 (a mixture of 1,3-dichloropropene and chloropicrin) under totally impermeable film (TIF) or with no surface seal, two injection depths (45 or 65 cm), and two biochar rates (20 or 40 ton ha-1). Emission rates were generally low due to rain events encountered during the trial, but data clearly showed that the deep injection enhanced fumigant delivery to depths below 60 cm and resulted in significantly lower peak emission compared to the standard injection depth. Biochar applied at 40 ton ha-1 had the lowest emission rates during 1-month monitoring period. Although variability in nematode survival was high, tarped, deep injection, and biochar treatment showed lower survival of nematodes at various depths. Increase in fumigant persistence, especially chloropicrin, was observed in this study, likely due to the high soil moisture and low temperature. All data indicate that biochar amendments can help reduce fumigant emissions without reducing nematode control; however, additional research is needed to optimize treatments, determine the affordability of various biochar materials, and validate results under a range of field conditions.