Measuring Flux of Soil Fumigants Using the Aerodynamic and Dynamic Flux Chamber Methods

Abstract

Methods for measuring and estimating flux density of soil fumigants under field conditions are important for the purpose of providing inputs to air dispersion models and for comparing the effects of management practices on emission reduction. The objective of this study was to measure the flux of 1,3-dichloropropene (1,3-D) and chloropicrin at a site in Georgia (GA) using the aerodynamic method and the dynamic flux chamber (FC) method. A secondary objective was to compare the effects of high density polyethylene (HDPE), and virtually impermeable film (VIF) tarps on fumigant flux at a site in Florida (FL). Chloropicrin and 1,3-D were applied by surface drip application of In-Line soil fumigant on vegetable beds covered by low density polyethylene (LDPE), HDPE, or VIF. The surface drip fumigation using In-Line and LDPE tarp employed in this study resulted in volatilization of 26.5% of applied 1,3-D and 11.2% of the applied chloropicrin at the GA site, as determined using the aerodynamic method. Estimates of mass loss obtained from dynamic FCs were 23.6% for 1,3-D and 18.0% for chloropicrin at the GA site. Flux chamber trials at the FL site indicate significant additional reduction in flux density, and cumulative mass loss when VIF tarp is used. This study supports the use of dynamic FCs as a valuable tool for estimating gas flux density from agricultural soils, and evaluating best management practices for reducing fumigant emissions to the atmosphere.

Estimating Field Volatility of Soil Fumigants Using CHAIN_2D: Mitigation Methods and Comparison Against Chloropicrin and 1,3-Dichloropropene Field Observations

“…A linear equation was fit to a semi-log plot of wind speed and concentration measurements to estimate values for each gradient. Details of the aerodynamic method are reported in [11,20].…”

“…The plot was irrigated for 3 h prior to the injection of the InLine fumigant (Trademark of Dow AgroSciences), a mixture of 60.2% 1,3-D and 33% chloropicrin. A total of 402.9 L (542.0 kg) of test material was used resulting in an application rate in the overall field (bed) of 186.5 kg/ha (350.6 kg/ha) and 192.2 kg/ha (102.2 kg/ha) for 1,3-D and chloropicrin, respectively [20]. A sandy loam soil texture was assumed for modeling purposes.…”

“…Field volatility studies have been conducted in various agricultural regions of the United States to measure the evaporation of soil fumigants applied to soil via shallow or deep shank injection, or via drip irrigation. Extensive field research of gas flux from soils have included methyl bromide [9,22,30], and to a lesser extent 1,3-dichloropropene (1,3-D) and chloropicrin [4,20,23,31,32]. Recent field studies have shown significant decreases in fumigant flux from soil via mitigation factors such as the increased depth of application, soil moisture, and organic matter, and the use of tarps at the soil surface [1,2,8].…”

Volatilisation of pesticides under field conditions: inverse modelling and pesticide fate models

“…In addition, it is expensive to measure directly the emission flux density from a treated area, although various technologies exist. 35 -40 It can be calculated from measurements of concentration in air close to the source. There are a number of methods for doing this, such as aerodynamic profile (ADP), energy balance (EB), relaxed eddy accumulation (REA) and plume dispersion (PD) methods.…”

Use of SOFEA to Predict 1,3‐D Concentrations in Air in High‐Use Regions of California

“…Approximately 90% of strawberry applications were made using a drip irrigation system. Drip applications using 1,3‐D are typically made under an agronomic film or tarp, and are taken into account by SOFEA (Cryer, 2005; Cryer et al, 2005; van Wesenbeeck et al, 2005).…”