1a.Objectives (from AD-416)
1) Replace methyl bromide with an alternative fumigant,
2) Reduce the application rates of pre-plant alternative fumigants through a combination of decreased losses by better retention with low permeability films and enhanced sub-surface dispersion by carbonation of the fumigants, and
3) To ascertain the minimum fumigation rate required to be effective in various soils in multiple states with a variety of crops under different tarping techniques.
1b.Approach (from AD-416)
Three field trials will be conducted to collect field data. Targeted cropping systems are deep-rooted perennial tree/ornamental/grapevine orchards or nurseries. Telone and chloropicrin products will be tested in all trials. The first two years will focus on filed trials to determine effective reduced rates of carbonated fumigants. In the third year, a demonstration trial will illustrate those successful fumigation methods in growers’ fields. Emission loss, fumigant distribution (or concentration change over time in soil profile), and efficacy on nematode, pathogen and weed control will all be determined. The expected outcome is an economically feasible alternative to methyl bromide by increasing use efficiency, reducing chemical input and minimizing detrimental impact on the environment.
This Reimbursable Agreement supports Objective 3 of the parent project. In February 2011, a field trial was conducted in a sandy soil with raised bed design prior to planting tomatoes in Florida. The purpose of the trial was to investigate effective fumigant dispersion in soil by carbonation and emission control by tarping with totally-impermeable film (TIF). Carbonated Telone C35 was shank applied at 151 kg ha-1 to 25 cm deep of the beds, which is about one third rate of maximum rate allowed in California. Fumigant emissions from raised-beds tarped with TIF and from bare furrows were monitored for 10 days. Changes of fumigant concentration across the beds under the tarp were monitored. Sample analyses and data compilation are complete. The TIF tarp reduced fumigant emissions to only 0.1% of totally applied 1,3-Dichloropropene from the beds. However, significantly high emissions (27% of applied) were measured from the furrows. Concentration changes under the tarp across the bed support movement of fumigants under the tarp to the furrows. The results suggest that emission control by tarping TIF over the beds is effective, but not good enough to reduce total emissions from the whole field. Proper bed designs and fumigation methods need to be adjusted to achieve overall emission reduction.