Emissions of 1,3-Dichloropropene and Chloropicrin after Soil Fumigation under Field Conditions

Abstract

Soil fumigation is an important agronomic practice in the production of many high-value vegetable and fruit crops, but the use of chemical fumigants can lead to excessive atmospheric emissions. A large-scale (2.9 ha) field experiment was conducted to obtain volatilization and cumulative emission rates for two commonly used soil fumigants under typical agronomic practices: 1,3-dichloropropene (1,3-D) and chloropicrin. The aerodynamic method and the indirect back-calculation method using ISCST3 and CALPUFF dispersion models were used to estimate flux loss from the treated field. Over the course of the experiment, the daily peak volatilization rates ranged from 12 to 30 μg m(-2) s(-1) for 1,3-D and from 0.7 to 2.6 μg m(-2) s(-1) for chloropicrin. Depending on the method used for quantification, total emissions of 1,3-D and chloropicrin, respectively, ranged from 16 to 35% and from 0.3 to 1.3% of the applied fumigant. A soil incubation study showed that the low volatilization rates measured for chloropicrin were due to particularly high soil degradation rates observed at this field site. Understanding and quantifying fumigant emissions from agricultural soil will help in developing best management practices to reduce emission losses, reducing adverse impacts to human and ecosystem health, and providing inputs for conducting risk assessments.

Effect of deep injection on field-scale emissions of 1,3-dichloropropene and chloropicrin from bare soil

“…For chloropicrin, emission rates were < 1.5 g m -2 s -1 . The low emission rates were due to high soil degradation rates observed for this soil type (Yates et al, 2015) and low chloropicrin application rates, leading to relatively low soil concentrations (Ashworth et al, 2015). The total chloropicrin emissions were found to be less than 1 % of applied for this study and less than 2% when injected at cm (Table 2, SI).…”

“…and two injection depths. For standard injection at cm (Yates et al, 2015), 1,3-D concentrations were generally higher compared to deep injection (i.e., 61 cm) with maxima of approximately 200 g m -3 at 30 m and 120 g m -3 at 90 and 120 m from the field edge. After approximately 3 days, the air concentrations became lower.…”

“…The ADM method yielded a cumulative emission that was 42-80 % larger than the other methods, and was a result of consistently higher emission rates throughout the experiment. When 1,3-D is applied at a depth of 46 cm (Yates et al, 2015) emissions calculated using the ADM were 35% (Table 2, SI). In previous research that used these methods for calculating the fumigant emission rate, it was found that the ADM was approximately 50% higher than the IHF and TPS methods (Yates et al, 2008).…”

“…These fumigants also have a relatively high vapor pressure (18-28 mmHg) so that losses to the atmosphere can be significant. In a previous paper, Yates et al (2015) reported on a field experiment conducted to measure the volatilization rate of 1,3-D and chloropicrin after application to a bare soil at 46 cm depth (SI) using a standard fumigation methodology. Using several methods for quantification, the reported total emissions of 1,3-D and chloropicrin, respectively, ranged from 16 -35% and 0.3 -1.3% of the applied fumigant.…”

“…The purpose of the present paper is to obtain emission measurements for soil fumigation employing deep injection, a proposed emission-reduction methodology. By comparison to the standard application methodology reported by Yates et al, (2015) an evaluation can be made to determine if deep injection effectively mitigates emissions.…”