Agricultural relies on fumigants as a pre-plant treatment. The continued availability of agricultural fumigants will require sound environmental management of off-gassing. The commercialization of research on enhanced sealing practice is needed to mitigate off-gassing consistent with cultural practice. The purpose of this research will be to commercialize the enhanced fumigant sealing method referred to as intermittent water sealing. The goal is to reduce the scope and extent of the implementatio of this method in order to meet better meet commercial needs. OBJECTIVES: Agriculture relies on continued availability of fumigants to promote high yields and quality crops. The phase-out of methyl bromide heightens the importance of effective and environmentally safe alternatives to methyl bromide. The continued availability of key alternatives depends on both performance and longterm environmental viability. The use of intermittent water sealing (additional water sealing during the first and second evening) has been demonstrated to substantially reduce offgassing, and potentially increases dose in the treatment zone. Intermittent water sealing methods have consistently shown excellent control for shank injection and chemigation applications for metam sodium. To date, the testing has focused on 15 to 20 acre per day applications, which is too low for many commercial applications. Phase I proposes field research at two application sites to confirm that 40 acre per day applications can be controlled effectively through modification of these methods. The proposed commercialization concept suitable for 40 acres / day will be compared to previous successful research that was limited to 20 acres per day). Phase I will use Metam-Sodium as a case study to compare off-gassing control, dose in the treatment zone, and efficacy based on two alternative water sealing methods. Phase II would identify ways to adapt the methodology to a broader set of methyl bromide alternatives. If this research is successful, the dissemination of the results of this research to commercial agricultural, growers will provide a practical method to maintain fumigation and planting schedules within a reasonable adaptation of current cultural practice. Such measures will be especially important in areas of urban encroachment when sufficient water is available for implementation. Through modification of these methods in Phase II for other fumigants, the long-term viability of a suite of replacements could be strengthened to meet future needs of agriculture, consistent with evolving regulatory requirements. APPROACH: Two treatment areas will be evaluated: Treatment 1 (reference). Ten acre application of Metam-Sodium by chemigation using standard water sealing methods (one half inch water seal immediately upon completion of the application and another one-half inch water seal during the second afternoon). Irrigation lines will be used in the standard manner, with the concurrent use of each line. (Total water use for sealing is 1 acre inch). Treatment 2 (alternative approach to intermittent water sealing. As in Treatment 1 but use an extra one half inch water seal starting 1 hour before sunset on the day of application, followed by another one half inch water seal starting 1-hour before sunset on the second day. The application will be applied in the same manner as Treatment 1, however, the water sealing will be performed using every other line, followed by the use of the switching over to the alternative set of lines. (Total water use for sealing is 1.5 acre-inch). Off gassing Analysis. A total of 20 air quality monitoring stations will be established. Coconut charcoal tubes will be used to adsorb the MITC. Every four hours for 48 hours, each of the tubes will be replaced and the completed sample is stored in dry ice for subsequent shipment to a contract laboratory for analysis. Meteorological monitoring stations will be established at s representative location between the two fields to collect wind speed and wind direction data at 3 and 6 m. Ambient temperature, relative humidity, solar radiation, and precipitation also will be collected. Normalized dispersion modeling (i.e., setting the field emission rate to a unit emission rate will be performed for each of the separate 4 hour periods. Through the use of a least squares analysis, the emission rates for each period will be computed and the uncertainty in the fit is established. Soils Analysis. The soils analysis will include monitoring of liquid-phase MITC for two days post-application at three depths (3, 6, and 18 inches) in the two treatment zones. The liquid phase samples of MITC in the treatment zone will be taken every 8 hours. Soil moisture and soil temperature will be monitored on a continuous basis during this 48 hour period. The evaluation of MITC partitioning into the gas, liquid, and solid phases will be included. An analysis of the water distribution effectiveness for both fields will be conducted. Efficacy Analysis. Replicated trials will be conducted for each treatment area to evaluate nematodes, fungi, and weed control. Dissemination of Research Results. Develop a peer reviewed technical article and grower oriented brochure (in addition to a technical report) that would be used to disseminate the methods and results of Phase I in technical form for researchers, in nontechnical terms for dissemination to growers
