Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 9/9/2008
Publication Date: 11/10/2008
Citation: Qin, R. S. Gao, B. Hanson, D. Wang, and J. Gerik. Shank designs and soil surface treatments on 1,3-d emissions in a nursery field trial. Ann. Int. Res. Conf. on MeBr Alternatives and Emission Reductions, San Diego, Nov. 11-15, 2008. p. 31-1 to 31-2. Interpretive Summary: As the only methyl bromide alternative accepted by CDFA’s Nursery Stock Nematode Certification program, Telone II (1,3-D) is subject to volatile organic compounds (VOCs) regulations due to concerns about emissions. Emission control through combination of shank designs (standard shank and Buessing shank) and post-fumigation soil surface treatments (plastic tarp and water seals) are evaluated in this research. Buessing shank gave similar 1,3-D emission but enhanced fumigant concentration and distribution in soil gas phases suggesting that Buessing shank may improve fumigation efficacy compared to the conventional shank. Tarping with VIF achieved the best fumigant emission reduction and retained highest fumigant concentrations in soil profile. HDPE tarp reduced half 1,3-D emission loss compared to the bare soil. Post-fumigation water seals only result in lower emission during the water application period.
Technical Abstract: In California, tree and grapevine field nurseries must meet the CDFA requirements for nematode-free planting stock. Telone II (1,3-D) is the only methyl bromide alternative accepted by CDFA’s Nursery Stock Nematode Certification program, but its use is subject to environmental regulations. A field trial was conducted in fall 2007 and evaluated combined effects of two shank designs (standard and Buessing shanks) and soil surface treatments (water seals and tarps with VIF and HDPE) on 1,3-D emissions and distribution in soil. The Buessing shank included two injection depths at 40 and 66 cm with shanks spaced 61 cm apart while a conventional shank had only one injection depth at 40 cm with shanks spaced 51 cm apart. Emission results showed no differences between the two shank designs; but varied substantial from surface treatments. Emission peak occurred from bare soils ~30 hr. A high emission peak occurred in water treatments after water applications completed (48 hr after fumigant application). The emission peak from HDPE treatments occurred at similar time but was reduced by about half compared to bare soils. The emission flux of VIF was substantially lower than other treatments. Cumulative emission loss was highest from bare soils, reduced 30% by water seals, 50% by HDPE, and >90% by VIF. Fumigant concentrations in the soil gas-phase were slightly higher in the Buessing shank treatments compared to the conventional shank in lower depth, and much higher in HDPE and VIF tarped plots especially VIF. Results rom this field trial indicates that the Buessing shank with the current design did not reduce 1,3-D emission but improve fumigant distribution in soil profile especially to lower depths that may enhance fumigation efficacy compared to the conventional shank. Tarping with VIF achieves the best fumigant reduction.