The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Scott R Yates - One of the best experts on this subject based on the ideXlab platform.
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biochar amendment to the soil surface reduces Fumigant emissions and enhances soil microorganism recovery
Environmental Science & Technology, 2016Co-Authors: Guoqing Shen, Daniel J Ashworth, Jay Gan, Scott R YatesAbstract:During soil fumigation, it is ideal to mitigate soil Fumigant emissions, ensure pest control efficacy, and speed up the recovery of the soil microorganism population established postapplication. However, no current Fumigant emission reduction strategy can meet all these requirements. In the present study, replicated soil columns were used to study the effect of biochar derived from rice husk (BR) and green waste (BG) applied to the soil surface on 1,3-dichloropropene (1,3-D) and chloropicrin (CP) emissions and soil gas distribution, and on microorganism population re-establishment. Relative to fumigated bare soil (no emission reduction strategy), high-density polyethylene (HDPE), and ammonium thiosulfate (ATS) treatments, BR gave dramatic emission reductions for both Fumigants with no obvious emission peak, whereas BG was very effective only for 1,3-D. With BR application, the concentration of Fumigant in the soil gas was higher than in the bare soil and ATS treatment. After the soil column experiment, mi...
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emissions of 1 3 dichloropropene and chloropicrin after soil fumigation under field conditions
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Scott R Yates, J A Knuteson, Daniel J Ashworth, Qiaoping Zhang, Wei Zheng, Ian J Van WessenbeeckAbstract: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 ...
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comparisons of soil surface sealing methods to reduce Fumigant emission loss
Journal of Environmental Quality, 2011Co-Authors: Suduan Gao, Ruijun Qin, Dong Wang, Bradley D Hanson, Scott R YatesAbstract:State and federal regulatory agencies depend on quality field data for determining the effects of agricultural management practices on Fumigant emissions to develop sound, science-based policies and regulations on preplant soil Fumigants. Field plot tests, using growers' standard field operation procedures, were used to simultaneously determine the effectiveness of several commonly proposed emission reduction methods, in a trial involving shank injection of Telone II [a.i. 1,3-dichloropropnene (1,3-D)] to a sandy loam soil to a target rate of 372 kg ha(-1). The experiment was conducted in late September 2008 in the San Joaquin Valley of California. Fumigant emissions were captured using dynamic flux chambers. The results showed that virtually impermeable film (VIF) reduced emissions >95% when compared to bare soil, and the glue joints in the film did not significantly affect the tarp performance. The VIF also created a more uniform distribution of gaseous Fumigant in the soil profile, which would likely benefit pest control efficacy. Standard high-density polyethylene (HDPE) tarp reduced total 1,3-D emissions about 50% (higher than most reported values) in this trial, whereas postfumigation intermittent water treatments (seals) reduced cumulative emission losses by approximately 20%. Adding 49.4 Mg ha (equivalent to 20 tons per acre) of composted dairy manure to surface soils did not reduce 1,3-D emissions during this experiment. Use of VIF was the most promising technique in reducing emissions and has the potential to allow lower application rates while providing satisfactory pest control.
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A standardized approach for estimating the permeability of plastic films to soil Fumigants under various field and environmental conditions.
Journal of environmental quality, 2011Co-Authors: Sharon K. Papiernik, Scott R Yates, Dan O. ChellemiAbstract:Minimizing atmospheric emissions of soil Fumigants is critical for protecting human and environmental health. Covering the soil surface with a plastic tarp is a common approach to restrict Fumigant emissions. The mass transfer of the Fumigant vapors through the tarp is often the rate-limiting factor in Fumigant emissions. An approach for standardizing measurements of film permeability is proposed that is based on determining the resistance (R) of films to diffusion of Fumigants. Using this approach, values were determined for more than 200 film-chemical combinations under a range of temperature, relative humidity, and film handling conditions. Resistance to diffusion was specific for each Fumigant/film combination, with the largest range of values observed for the Fumigant chloropicrin. For each Fumigant, decreased with increasing temperature. Changes in film permeability due to increases in temperature or field installation were generally less than a factor of five. For one film, values determined under conditions of very high relative humidity (approximately 100%) were at least 100 times lower than when humidity was very low (approximately 2%). This approach simplifies the selection of appropriate films for soil fumigation by providing rapid, reproducible, and precise measurements of their permeability to specific Fumigants and application conditions.
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determining breakthrough of the soil Fumigant chloropicrin from 120 mg xad 4 sorbent tubes
Atmospheric Environment, 2008Co-Authors: Daniel J Ashworth, Wei Zheng, Scott R YatesAbstract:Abstract The emission to the atmosphere of soil Fumigants such as chloropicrin represents a potentially important human exposure pathway. Commonly, determining the air concentration of Fumigants is carried out by pumping air through sorbent tubes which chemically retain the Fumigant. In order to obtain an accurate measurement, it is essential that the Fumigant does not break through the sorbent tubes, since this would result in an underestimation. Using a simple apparatus, we tested the potential for chloropicrin breakthrough from 120 mg XAD-4 sorbent tubes. The effects of chloropicrin loading (0.33 and 3.3 mg) and air flow rate (50 and 1000 mL min−1) on the transport of chloropicrin through six XAD-4 tubes (connected in series) were examined over time periods ranging from 1 to 360 min. The higher flow rate led to rapid and high breakthrough of the chloropicrin, especially at the longer time periods. At 360 min, all six tubes together retained only 46–54% (depending on initial loading) of the added chloropicrin. At the lower flow rate, essentially all of the added chloropicrin was always retained on the first two tubes. The effect of flow rate was greater than that of initial chloropicrin loading and sampling time. It is concluded that when 120 mg XAD-4 tubes are used in soil Fumigant emission studies, it should be at low flow rates only and always with at least one back-up tube.
Bradley D Hanson - One of the best experts on this subject based on the ideXlab platform.
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Off-tarp emissions, distribution, and efficacy of carbonated Fumigants in a low permeability film tarped field.
The Science of the total environment, 2017Co-Authors: Ruijun Qin, Suduan Gao, John E Thomas, Dong Wang, Bradley D HansonAbstract:Carbonated Fumigants have been shown to distribute quickly and uniformly in sandy soils and improve pest control efficacy for annual crops. Low permeability films, such as VaporSafe® (TIF), could further improve Fumigant dispersion by effectively retaining the Fumigant in soil; however, there is a concern that the TIF can lead to higher off-tarp edge emissions. An orchard field trial was conducted to determine the off-tarp emissions, distribution, efficacy, and fate of carbonated Telone® C35 [63.4% 1,3-dichloropropene (1,3-D), 34.7% chloropicrin (CP)] that was shank-injected at 46cm soil depth. Treatments included carbonated Fumigants at full- or 2/3 rates and a full rate of regular (nitrogen-pressurized) Fumigants covered with standard polyethylene (PE) film, TIF, or no surface seal. Fumigant emissions at the regular tarp edge (25cm from the shank line) peaked at 3.98μgm-2s-1 for 1,3-D and 0.05μgm-2s-1 for CP. The addition of a TIF tarp extension (to 85cm from the shank line) reduce peak off-tarp emissions to
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Effect of application rate on Fumigant degradation in five agricultural soils.
The Science of the total environment, 2015Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Bradley D HansonAbstract:Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how Fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four Fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all Fumigants in the Hueneme sandy loam soil was reduced by 50-95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the Fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios.
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Managing the almond and stone fruit replant disease complex with less soil Fumigant
California Agriculture, 2013Co-Authors: Greg T. Browne, Bruce Lampinen, Brent A. Holtz, David Doll, Shrinivasa K. Upadhyaya, L. Schmidt, R Bhat, Udompetaikul, Robert W Coates, Bradley D HansonAbstract:As much as one-third of California's almond and stone fruit acreage is infested with potentially debilitating plant parasitic nematodes, and even more of the land is impacted by Prunus replant disease (PRD), a poorly understood soilborne disease complex that suppresses early growth and cumulative yield in replanted almond and peach orchards. Preplant soil fumigation has controlled these key replant problems, but the traditional Fumigant of choice, methyl bromide, has been phased out, and other soil Fumigants are increasingly regulated and expensive. We tested Fumigant and nonFumigant alternatives to methyl bromide in multiple-year replant trials. Costs and benefits were evaluated for alternative Fumigants applied by shanks in conventional strip and full-coverage treatments and applied by shanks or drip in novel spot treatments that targeted tree planting sites. Short-term sudangrass rotation and prudent rootstock selection were examined as nonFumigant approaches to managing PRD. Trial results indicated that integrations of the treatments may acceptably control PRD with relatively little soil Fumigant.
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comparisons of soil surface sealing methods to reduce Fumigant emission loss
Journal of Environmental Quality, 2011Co-Authors: Suduan Gao, Ruijun Qin, Dong Wang, Bradley D Hanson, Scott R YatesAbstract:State and federal regulatory agencies depend on quality field data for determining the effects of agricultural management practices on Fumigant emissions to develop sound, science-based policies and regulations on preplant soil Fumigants. Field plot tests, using growers' standard field operation procedures, were used to simultaneously determine the effectiveness of several commonly proposed emission reduction methods, in a trial involving shank injection of Telone II [a.i. 1,3-dichloropropnene (1,3-D)] to a sandy loam soil to a target rate of 372 kg ha(-1). The experiment was conducted in late September 2008 in the San Joaquin Valley of California. Fumigant emissions were captured using dynamic flux chambers. The results showed that virtually impermeable film (VIF) reduced emissions >95% when compared to bare soil, and the glue joints in the film did not significantly affect the tarp performance. The VIF also created a more uniform distribution of gaseous Fumigant in the soil profile, which would likely benefit pest control efficacy. Standard high-density polyethylene (HDPE) tarp reduced total 1,3-D emissions about 50% (higher than most reported values) in this trial, whereas postfumigation intermittent water treatments (seals) reduced cumulative emission losses by approximately 20%. Adding 49.4 Mg ha (equivalent to 20 tons per acre) of composted dairy manure to surface soils did not reduce 1,3-D emissions during this experiment. Use of VIF was the most promising technique in reducing emissions and has the potential to allow lower application rates while providing satisfactory pest control.
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field evaluation of a new plastic film vapor safe to reduce Fumigant emissions and improve distribution in soil
Journal of Environmental Quality, 2011Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Dong Wang, David A Sullivan, Bradley D HansonAbstract:Preplant soil fumigation is an important pest management practice in coastal California strawberry production regions. Potential atmospheric emissions of Fumigants from field treatment, however, have drawn intensive environmental and human health concerns; increasingly stringent regulations on Fumigant use have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low-permeability film, commonly known as totally impermeable film (TIF), on Fumigant emissions and on Fumigant distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha in two location-separate field plots (0.4 ha each) in Ventura County, California, in fall 2009. One plot was surface-covered with standard polyethylene (PE) film, and the other was covered with TIF immediately after Fumigant application. Data collection included emissions, soil-gas phase concentration profile, air concentration under the film, and soil residuals of the applied Fumigants. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than from the PE field. Total through-film emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d film covering period, compared with 43% for 1,3-D and 12% for CP from the PE field. However, on film-cutting, greater retention of 1,3-D in the TIF field resulted in a much higher emission surge compared with the PE field, while CP emissions were fairly low in both fields. Higher concentrations and a more uniform distribution in the soil profile for 1,3-D and CP were observed under the TIF compared with the PE film, suggesting that the TIF may allow growers to achieve satisfactory pest control with lower Fumigant rates. The surging 1,3-D emissions after film-cutting could result in high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.
Sharon K. Papiernik - One of the best experts on this subject based on the ideXlab platform.
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A standardized approach for estimating the permeability of plastic films to soil Fumigants under various field and environmental conditions.
Journal of environmental quality, 2011Co-Authors: Sharon K. Papiernik, Scott R Yates, Dan O. ChellemiAbstract:Minimizing atmospheric emissions of soil Fumigants is critical for protecting human and environmental health. Covering the soil surface with a plastic tarp is a common approach to restrict Fumigant emissions. The mass transfer of the Fumigant vapors through the tarp is often the rate-limiting factor in Fumigant emissions. An approach for standardizing measurements of film permeability is proposed that is based on determining the resistance (R) of films to diffusion of Fumigants. Using this approach, values were determined for more than 200 film-chemical combinations under a range of temperature, relative humidity, and film handling conditions. Resistance to diffusion was specific for each Fumigant/film combination, with the largest range of values observed for the Fumigant chloropicrin. For each Fumigant, decreased with increasing temperature. Changes in film permeability due to increases in temperature or field installation were generally less than a factor of five. For one film, values determined under conditions of very high relative humidity (approximately 100%) were at least 100 times lower than when humidity was very low (approximately 2%). This approach simplifies the selection of appropriate films for soil fumigation by providing rapid, reproducible, and precise measurements of their permeability to specific Fumigants and application conditions.
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Incompatibility of metam sodium with halogenated Fumigants
Pest management science, 2005Co-Authors: Mingxin Guo, Scott R Yates, Sharon K. Papiernik, Wei ZhengAbstract:Metam sodium (metam) is a widely used soil Fumigant. Combined application of metam and other available Fumigants is intended to produce synergic pesticidal effects for a broad spectrum of pest control in soil fumigation. This study aimed to test the compatibility of metam with the halogenated Fumigants 1,3-dichloropropene (1,3-D), chloropicrin, methyl bromide, methyl iodide and propargyl bromide. Halogenated Fumigants and metam were spiked simultaneously into organic solvents, water and moist soils, and metam-induced degradation of these halogenated chemicals was evaluated. In all three media, the halogenated Fumigants were incompatible with metam and degraded via rapid chemical reactions. The degradation rate varied with halogenated Fumigant species and increased as the amount of metam present was increased. In moist soil, 15-95% of the halogenated Fumigants were decomposed within 72 h by metam at a 1:1 molar ratio. Combined application of Telone C-35 (62.5% 1,3-D + 35% chloropicrin) at 265 mg kg(-1) and Vapam (42% metam) at 567 mg kg(-1) in soil resulted in complete disappearance of the applied chloropicrin and 20-38% of the 1,3-D within 8 h. The results suggest that simultaneous application of halogenated Fumigants and metam at the same soil depth will not maximize pest control. In practice, sequential treatment of soil or application at different soil depths is recommended when these two types of Fumigants are used in combination.
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effect of combined application of methyl isothiocyanate and chloropicrin on their transformation
Journal of Environmental Quality, 2004Co-Authors: Scott R Yates, Wei Zheng, Sharon K. PapiernikAbstract:Combining several soil Fumigants to increase the broad spectrum of pest control is a common fumigation practice in current production agriculture. In this study, we investigated the effect of combined application of chloropicrin and methyl isothiocyanate (MITC) on their transformations and persistence in the environment. In aqueous solution, no direct reaction between MITC and chloropicrin occurred and relatively slow rates of hydrolysis of these compounds were observed in aquatic environments free of suspended solids. The transformation of chloropicrin, however, was accelerated in aqueous solution with MITC because of a reduction reaction with bisulfide (HS ), which is a by-product of MITC hydrolysis. In soil, when Fumigants were applied simultaneously, the degradation of MITC was suppressed under the bi-Fumigant application due to the inhibition of soil microbial activity and a possible abiotic competition with chloropicrin for a limited number of reaction sites on the surface of soil particles. However, the degradation rate of chloropicrin was significantly enhanced in the bi-Fumigant soil system, which was primarily attributed to the reaction of chloropicrin and HS . Two sequential application approaches were developed to investigate the feasibility of the combined application of metam sodium (parent compound of MITC) and chloropicrin in soil and assess their potential effects on environmental fate. For both application sequences, the degradation of chloropicrin was accelerated and that of MITC, as a major breakdown product of metam sodium, was inhibited in soil.
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Effect of application variables on emissions and distribution of Fumigants applied via subsurface drip irrigation.
Environmental science & technology, 2004Co-Authors: Sharon K. Papiernik, Wei Zheng, Robert S. Dungan, Scott M. Lesch, Mingxin Guo, Scott R YatesAbstract:Soil fumigation is useful for controlling soil-borne pests and diseases in high-cash-value crops. Fumigants are highly volatile, and approaches to reduce atmospheric emissions are required to protect human and environmental health. Application of Fumigants through drip irrigation has been proposed as a means to decrease Fumigant emissions, improve Fumigant distribution in soil, and minimize worker exposure. These experiments were conducted to investigate the effect of the configuration of the drip system on the volatilization and distribution of the Fumigants 1,3-dichloropropene (1,3-D), propargyl bromide (PrBr), and methyl isothiocyanate (MITC) in bedded systems. Results indicated that changing the drip emitter spacing and using multiple drip lines in each bed had little effect on the emissions and distribution of any Fumigant. Increasing the depth of application from 15 to 30 cm reduced volatilization of MITC by approximately 20 to >90%; emissions were reduced due to a decrease in the flux from the bed top, and deeper injection did not change the amount of Fumigant volatilized from the bed side slope and furrow. Increasing the application depth resulted in a slight decrease in the rate of Fumigant dissipation in soil, indicating the potential for some improvement in pest-control efficacy with deeper application.
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Effect of surface tarp on emissions and distribution of drip-applied Fumigants.
Environmental science & technology, 2004Co-Authors: Sharon K. Papiernik, Scott R Yates, Wei Zheng, Robert S. Dungan, Scott M. Lesch, Mingxin GuoAbstract:Soil Fumigants are used to control a wide variety of soil-borne pests in high-cash-value crops. Application of soil Fumigants through drip irrigation systems is receiving increasing attention as a method to improve the uniformity of Fumigant application. Little information is available on the emissions and soil distribution of Fumigants following subsurface drip application, or the effect of plastic tarp on Fumigant emissions in these systems. In these experiments, the Fumigant compounds 1,3-dichloropropene (1,3-D), Vapam (a methyl isothiocyanate (MITC) precursor), and propargyl bromide (PrBr) were applied to soil beds via drip irrigation at 15 cm depth. Beds were tarped with either standard 1-mil high-density polyethylene (HDPE) or a virtually impermeable film (VIF), leaving the furrows bare. Cumulative emissions of 1,3-D, MITC, and PrBr in these tarped bedded systems was very low, amounting to
Ruijun Qin - One of the best experts on this subject based on the ideXlab platform.
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Off-tarp emissions, distribution, and efficacy of carbonated Fumigants in a low permeability film tarped field.
The Science of the total environment, 2017Co-Authors: Ruijun Qin, Suduan Gao, John E Thomas, Dong Wang, Bradley D HansonAbstract:Carbonated Fumigants have been shown to distribute quickly and uniformly in sandy soils and improve pest control efficacy for annual crops. Low permeability films, such as VaporSafe® (TIF), could further improve Fumigant dispersion by effectively retaining the Fumigant in soil; however, there is a concern that the TIF can lead to higher off-tarp edge emissions. An orchard field trial was conducted to determine the off-tarp emissions, distribution, efficacy, and fate of carbonated Telone® C35 [63.4% 1,3-dichloropropene (1,3-D), 34.7% chloropicrin (CP)] that was shank-injected at 46cm soil depth. Treatments included carbonated Fumigants at full- or 2/3 rates and a full rate of regular (nitrogen-pressurized) Fumigants covered with standard polyethylene (PE) film, TIF, or no surface seal. Fumigant emissions at the regular tarp edge (25cm from the shank line) peaked at 3.98μgm-2s-1 for 1,3-D and 0.05μgm-2s-1 for CP. The addition of a TIF tarp extension (to 85cm from the shank line) reduce peak off-tarp emissions to
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Effect of application rate on Fumigant degradation in five agricultural soils.
The Science of the total environment, 2015Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Bradley D HansonAbstract:Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how Fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four Fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all Fumigants in the Hueneme sandy loam soil was reduced by 50-95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the Fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios.
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comparisons of soil surface sealing methods to reduce Fumigant emission loss
Journal of Environmental Quality, 2011Co-Authors: Suduan Gao, Ruijun Qin, Dong Wang, Bradley D Hanson, Scott R YatesAbstract:State and federal regulatory agencies depend on quality field data for determining the effects of agricultural management practices on Fumigant emissions to develop sound, science-based policies and regulations on preplant soil Fumigants. Field plot tests, using growers' standard field operation procedures, were used to simultaneously determine the effectiveness of several commonly proposed emission reduction methods, in a trial involving shank injection of Telone II [a.i. 1,3-dichloropropnene (1,3-D)] to a sandy loam soil to a target rate of 372 kg ha(-1). The experiment was conducted in late September 2008 in the San Joaquin Valley of California. Fumigant emissions were captured using dynamic flux chambers. The results showed that virtually impermeable film (VIF) reduced emissions >95% when compared to bare soil, and the glue joints in the film did not significantly affect the tarp performance. The VIF also created a more uniform distribution of gaseous Fumigant in the soil profile, which would likely benefit pest control efficacy. Standard high-density polyethylene (HDPE) tarp reduced total 1,3-D emissions about 50% (higher than most reported values) in this trial, whereas postfumigation intermittent water treatments (seals) reduced cumulative emission losses by approximately 20%. Adding 49.4 Mg ha (equivalent to 20 tons per acre) of composted dairy manure to surface soils did not reduce 1,3-D emissions during this experiment. Use of VIF was the most promising technique in reducing emissions and has the potential to allow lower application rates while providing satisfactory pest control.
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field evaluation of a new plastic film vapor safe to reduce Fumigant emissions and improve distribution in soil
Journal of Environmental Quality, 2011Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Dong Wang, David A Sullivan, Bradley D HansonAbstract:Preplant soil fumigation is an important pest management practice in coastal California strawberry production regions. Potential atmospheric emissions of Fumigants from field treatment, however, have drawn intensive environmental and human health concerns; increasingly stringent regulations on Fumigant use have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low-permeability film, commonly known as totally impermeable film (TIF), on Fumigant emissions and on Fumigant distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha in two location-separate field plots (0.4 ha each) in Ventura County, California, in fall 2009. One plot was surface-covered with standard polyethylene (PE) film, and the other was covered with TIF immediately after Fumigant application. Data collection included emissions, soil-gas phase concentration profile, air concentration under the film, and soil residuals of the applied Fumigants. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than from the PE field. Total through-film emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d film covering period, compared with 43% for 1,3-D and 12% for CP from the PE field. However, on film-cutting, greater retention of 1,3-D in the TIF field resulted in a much higher emission surge compared with the PE field, while CP emissions were fairly low in both fields. Higher concentrations and a more uniform distribution in the soil profile for 1,3-D and CP were observed under the TIF compared with the PE film, suggesting that the TIF may allow growers to achieve satisfactory pest control with lower Fumigant rates. The surging 1,3-D emissions after film-cutting could result in high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.
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Spot Fumigation: Fumigant Gas Dispersion and Emission Characteristics
Environmental science & technology, 2009Co-Authors: Dong Wang, Ruijun Qin, Suduan Gao, Bradley D Hanson, Greg T. Browne, James S. Gerik, Nishanth TharayilAbstract:Reducing emissions of volatile organic compounds (VOCs) from Fumigant pesticides is mandatory in California, especially in "nonattainment areas" like the San Joaquin Valley that do not meet federal air quality standards. A two-year field study was conducted to examine the feasibility of site-specific Fumigant application only at future tree sites with dramatically reduced amounts of Fumigant chemicals on an orchard basis. Soil gas distribution and atmospheric emission of 1,3-dichloropropene and chloropicrin were measured after applying InLine using subsurface drip irrigation. It was predicted that except in the surface 20 cm of soil, satisfactory pest control could be achieved within a 15 cm radius from the injection point. Also, at radial distances of 15-51 cm from the point of Fumigant injection, effective nematode control may be achieved. Cumulative atmospheric emission of the Fumigants was estimated to be 18-23% of the applied active ingredients in plots that had been cover cropped with Sudan grass and 2-6% in plots that had remained bare for several months before treatment. Considering the significantly small amount of Fumigant used on an orchard basis, the spot drip fumigation may achieve a 10-fold reduction in atmospheric VOCs load from Fumigant pesticides.
Suduan Gao - One of the best experts on this subject based on the ideXlab platform.
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Off-tarp emissions, distribution, and efficacy of carbonated Fumigants in a low permeability film tarped field.
The Science of the total environment, 2017Co-Authors: Ruijun Qin, Suduan Gao, John E Thomas, Dong Wang, Bradley D HansonAbstract:Carbonated Fumigants have been shown to distribute quickly and uniformly in sandy soils and improve pest control efficacy for annual crops. Low permeability films, such as VaporSafe® (TIF), could further improve Fumigant dispersion by effectively retaining the Fumigant in soil; however, there is a concern that the TIF can lead to higher off-tarp edge emissions. An orchard field trial was conducted to determine the off-tarp emissions, distribution, efficacy, and fate of carbonated Telone® C35 [63.4% 1,3-dichloropropene (1,3-D), 34.7% chloropicrin (CP)] that was shank-injected at 46cm soil depth. Treatments included carbonated Fumigants at full- or 2/3 rates and a full rate of regular (nitrogen-pressurized) Fumigants covered with standard polyethylene (PE) film, TIF, or no surface seal. Fumigant emissions at the regular tarp edge (25cm from the shank line) peaked at 3.98μgm-2s-1 for 1,3-D and 0.05μgm-2s-1 for CP. The addition of a TIF tarp extension (to 85cm from the shank line) reduce peak off-tarp emissions to
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Effect of application rate on Fumigant degradation in five agricultural soils.
The Science of the total environment, 2015Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Bradley D HansonAbstract:Soil fumigation is an important pest management tool for many high value crops. To address the knowledge gap of how Fumigant concentration in soil impacts dissipation, and thereby efficacy, this research determined the degradation characteristics of four Fumigants as affected by application rate. Laboratory incubation experiments were conducted to determine degradation rates of 1,3-dichloropropene (both cis- and trans isomers), chloropicrin (CP), dimethyl disulfide (DMDS), and methyl iodide (MeI) in five agricultural soils. Fitted to pseudo first-order kinetics, the degradation rate constant (k) of CP, DMDS, and MeI decreased significantly as application rate increased while the 1,3-D isomers were the least affected by rate. Half-lives increased 12, 17, and 6-fold for CP, DMDS, and MeI, respectively, from the lowest to the highest application rate. At low application rates, the degradation rate of all Fumigants in the Hueneme sandy loam soil was reduced by 50-95% in sterilized soil compared to the biologically active controls. However, this difference became much smaller or disappeared at high application rates indicating that biodegradation dominates at low concentrations but chemical degradation is more important at high concentrations. When co-applied, CP degradation was enhanced with biodegradation remained above 50%, while 1,3-D degradation was either reduced or not changed. Among the Fumigants tested, the relative importance of biodegradation was DMDS>CP>MeI>1,3-D. These results are useful for determining effective fumigation rates and for informing regulatory decisions on emission controls under different fumigation scenarios.
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comparisons of soil surface sealing methods to reduce Fumigant emission loss
Journal of Environmental Quality, 2011Co-Authors: Suduan Gao, Ruijun Qin, Dong Wang, Bradley D Hanson, Scott R YatesAbstract:State and federal regulatory agencies depend on quality field data for determining the effects of agricultural management practices on Fumigant emissions to develop sound, science-based policies and regulations on preplant soil Fumigants. Field plot tests, using growers' standard field operation procedures, were used to simultaneously determine the effectiveness of several commonly proposed emission reduction methods, in a trial involving shank injection of Telone II [a.i. 1,3-dichloropropnene (1,3-D)] to a sandy loam soil to a target rate of 372 kg ha(-1). The experiment was conducted in late September 2008 in the San Joaquin Valley of California. Fumigant emissions were captured using dynamic flux chambers. The results showed that virtually impermeable film (VIF) reduced emissions >95% when compared to bare soil, and the glue joints in the film did not significantly affect the tarp performance. The VIF also created a more uniform distribution of gaseous Fumigant in the soil profile, which would likely benefit pest control efficacy. Standard high-density polyethylene (HDPE) tarp reduced total 1,3-D emissions about 50% (higher than most reported values) in this trial, whereas postfumigation intermittent water treatments (seals) reduced cumulative emission losses by approximately 20%. Adding 49.4 Mg ha (equivalent to 20 tons per acre) of composted dairy manure to surface soils did not reduce 1,3-D emissions during this experiment. Use of VIF was the most promising technique in reducing emissions and has the potential to allow lower application rates while providing satisfactory pest control.
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field evaluation of a new plastic film vapor safe to reduce Fumigant emissions and improve distribution in soil
Journal of Environmental Quality, 2011Co-Authors: Ruijun Qin, Husein A. Ajwa, Suduan Gao, Dong Wang, David A Sullivan, Bradley D HansonAbstract:Preplant soil fumigation is an important pest management practice in coastal California strawberry production regions. Potential atmospheric emissions of Fumigants from field treatment, however, have drawn intensive environmental and human health concerns; increasingly stringent regulations on Fumigant use have spurred research on low-emission application techniques. The objectives of this research were to determine the effects of a new low-permeability film, commonly known as totally impermeable film (TIF), on Fumigant emissions and on Fumigant distribution in soil. A 50/50 mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) was shank-applied at 314 kg ha in two location-separate field plots (0.4 ha each) in Ventura County, California, in fall 2009. One plot was surface-covered with standard polyethylene (PE) film, and the other was covered with TIF immediately after Fumigant application. Data collection included emissions, soil-gas phase concentration profile, air concentration under the film, and soil residuals of the applied Fumigants. Peak emission flux of 1,3-D and CP from the TIF field was substantially lower than from the PE field. Total through-film emission loss was 2% for 1,3-D and <1% for CP from the TIF field during a 6-d film covering period, compared with 43% for 1,3-D and 12% for CP from the PE field. However, on film-cutting, greater retention of 1,3-D in the TIF field resulted in a much higher emission surge compared with the PE field, while CP emissions were fairly low in both fields. Higher concentrations and a more uniform distribution in the soil profile for 1,3-D and CP were observed under the TIF compared with the PE film, suggesting that the TIF may allow growers to achieve satisfactory pest control with lower Fumigant rates. The surging 1,3-D emissions after film-cutting could result in high exposure risks to workers and bystanders and must be addressed with additional mitigation measures.
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Spot Fumigation: Fumigant Gas Dispersion and Emission Characteristics
Environmental science & technology, 2009Co-Authors: Dong Wang, Ruijun Qin, Suduan Gao, Bradley D Hanson, Greg T. Browne, James S. Gerik, Nishanth TharayilAbstract:Reducing emissions of volatile organic compounds (VOCs) from Fumigant pesticides is mandatory in California, especially in "nonattainment areas" like the San Joaquin Valley that do not meet federal air quality standards. A two-year field study was conducted to examine the feasibility of site-specific Fumigant application only at future tree sites with dramatically reduced amounts of Fumigant chemicals on an orchard basis. Soil gas distribution and atmospheric emission of 1,3-dichloropropene and chloropicrin were measured after applying InLine using subsurface drip irrigation. It was predicted that except in the surface 20 cm of soil, satisfactory pest control could be achieved within a 15 cm radius from the injection point. Also, at radial distances of 15-51 cm from the point of Fumigant injection, effective nematode control may be achieved. Cumulative atmospheric emission of the Fumigants was estimated to be 18-23% of the applied active ingredients in plots that had been cover cropped with Sudan grass and 2-6% in plots that had remained bare for several months before treatment. Considering the significantly small amount of Fumigant used on an orchard basis, the spot drip fumigation may achieve a 10-fold reduction in atmospheric VOCs load from Fumigant pesticides.
