Biochar significantly reduced fumigant emissions and benefited germination and plant growth under field conditions.

Soil fumigation continues to play an important role in soil disinfection, but tools to significantly reduce emissions while providing environmental benefits (e.g., biochar) are lacking.

Striking a balance between N sources: Mitigating soil acidification and accumulation of phosphorous and heavy metals from manure.

Manure amendment has been shown to effectively prevent red soil (Ferralic Cambisol) acidification from chemical nitrogen (N) fertilization. However, information is lacking on how much manure is needed to mitigate acidification and maintain soil productivity while preventing accumulation of other nutrients and heavy metals from long-term inputs. This study determined the effects of various combinations of manure with urea-N on acidification and changes in soil P, K, and heavy metals in a 9-year maize field experiment in southern China.

Nitrogen dynamics affected by biochar and irrigation level in an onion field.

Soil amended with biochar has many potential environmental benefits, but its influence on the fate of nitrogen (N) under irrigated conditions is unclear. The objective of this research was to determine the effects of biochar and interactions with irrigation on N movement in soil, gas emissions, and leaching. A three-year study was conducted in an onion field with three main irrigation treatments (50, 75, and 100% of a reference that provided sufficient water for plant growth) and three biochar amendment rates (0 or control, low char - applied first year at 29 Mg ha, and high char - added both first and second year for a total 58 Mg ha) as sub-treatments in a split-plot design.

Deep injection and the potential of biochar to reduce fumigant emissions and effects on nematode control.

Reducing fumigant emissions is essential for minimizing the environmental impacts of pre-plant soil fumigation. Low permeability plastic films are effective at reducing emissions but have high initial purchase, installation, and disposal costs. The objective of this study was to evaluate if deep fumigant injection and biochar soil amendments can reduce emissions, improve fumigant distribution in soil, and provide acceptable control of plant parasitic nematodes.

Evaluation of potassium thiosulfate as a nitrification inhibitor to reduce nitrous oxide emissions.

Potassium thiosulfate (KTS, KSO) has been shown to function as a nitrification inhibitor, thus has the potential to reduce nitrous oxide (NO) emissions and play an important role in effective N management. The objective of this research was to determine the potential effects of KTS on NO emissions and N transformation processes in comparison with commercial N transformation inhibitors (stabilizers). A laboratory incubation experiment was conducted using urea and ammonium nitrate (UAN) applied at 150mgNkg in a Hanford sandy loam soil (coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents).

Off-tarp emissions, distribution, and efficacy of carbonated fumigants in a low permeability film tarped field.

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.

Long-term incorporation of manure with chemical fertilizers reduced total nitrogen loss in rain-fed cropping systems.

Improving soil fertility/productivity and reducing environmental impact of nitrogen (N) fertilization are essential for sustainable agriculture. Quantifying the contribution of various fertilization regimes to soil N storage and loss has been lacking in a wide range of spatiotemporal scales. Based on data collected from field experiments at three typical agricultural zones in China, soil N dynamics and N changes in soil profile (0-100 cm) were examined during 1990-2009 under chemical fertilization, manure incorporation with fertilizer, and fertilizer with straw return treatments.

Mechanisms for 1,3-Dichloropropene Dissipation in Biochar-Amended Soils.

Biochar, which is organic material heated under a limited supply of oxygen, has the potential to reduce fumigant emissions when incorporated in the soil, but the mechanisms are not fully understood. The objective of this study was to determine the effects of biochar properties, amendment rate, soil microbe, moisture, temperature, and soil type on the fate of 1,3-dichloropropene (1,3-D) isomers in laboratory incubation experiments by assessing the 1,3-D degradation rate and adsorption capacity. 1,3-D dissipation rates were significantly reduced due to strong adsorption by biochar, which was also strongly affected by biochar type.

Effect of application rate on fumigant degradation in five agricultural soils.

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.

Fumigation efficacy and emission reduction using low-permeability film in orchard soil fumigation.

Background: Many orchards use fumigation to control soilborne pests prior to replanting. Controlling emissions is mandatory to reduce air pollution in California. This research evaluated the effects of plastic film type [polyethylene (PE) or totally impermeable film (TIF)], application rate of Telone C35 [full (610 kg ha(-1) ), 2/3 or 1/3 rates] and carbonation at 207 kPa on fumigant transport (emission and in soil) and efficacy.

Emissions from soil fumigation in two raised bed production systems tarped with low permeability films.

Raised beds are used to produce some high-value annual fruit and vegetable crops such as strawberry in California (CA) and tomato in Florida (FL), USA. Pre-plant soil fumigation is an important tool to control soil-borne pests in the raised beds. However, fumigant emissions have detrimental environmental consequences.

Emission and transport of 1,3-dichloropropene and chloropicrin in a large field tarped with VaporSafe TIF.

Tarping fumigated fields with low permeability films such as commercial Totally Impermeable Film (TIF) can significantly reduce emissions, but it can also increase fumigant residence time in the soil such that extended tarp-covering durations may be required to address potential exposure risks during tarp-cutting and removal. In an effort to develop safe practices for using TIF, a large field study was conducted in the San Joaquin Valley of California. Comprehensive data on emissions (measured with dynamic flux chambers), fate, and transport of 1,3-dichloropropene and chloropicrin were collected in a 3.

Emission and distribution of fumigants as affected by soil moistures in three different textured soils.

Water application is a low-cost strategy to control emissions of soil fumigant to meet the requirements of the stringent environmental regulations and it is applicable for a wide range of commodity groups. Although it is known that an increase in soil moisture reduces emissions, the range of soil moisture for minimizing emissions without risking pest control, is not well defined for various types of soils. With two column studies, we determined the effect of different soil moisture levels on emission and distribution of 1,3-dichloropropene and chloropicrin in three different textured soils.

Comparisons of soil surface sealing methods to reduce fumigant emission loss.

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.

Effects of surface treatments and application shanks on nematode, pathogen and weed control with 1,3-dichloropropene.

Background: Preplant fumigation with methyl bromide (MeBr) has been used for control of soilborne pests in high-value annual, perennial and nursery crops, but is being phased out. In 2007 and 2008, research trials were conducted to evaluate the effects of surface treatments and two application shanks on pest control with 1,3-dicloropropene (1,3-D) in perennial crop nurseries.

Results: All 1,3-D treatments controlled nematodes similarly to MeBr.

Field evaluation of a new plastic film (vapor safe) to reduce fumigant emissions and improve distribution in soil.

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.

Interactive effect of organic amendment and environmental factors on degradation of 1,3-dichloropropene and chloropicrin in soil.

Soil organic matter is an important factor affecting the fate of soil fumigants; therefore, the addition of organic amendments to surface soils could reduce fumigant emissions by accelerating fumigant degradation. Experiments were conducted to determine the degradation of fumigants [a mixture of cis- and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP), a similar composition as in Telone C35] in soils with organic amendment under a range of soil moisture, temperature, sterilization, and texture conditions. Degradation of the fumigants followed availability-adjusted first-order or pseudo-first-order kinetics with slower degradation of 1,3-D than CP.

Effects of manure and water applications on 1,3-dichloropropene and chloropicrin emissions in a field trial.

Minimizing fumigant emissions is required for meeting air-quality standards. Application of organic materials to surface soil has been effective in reducing fumigant emissions during laboratory tests, but the potential to reduce emissions in the field has not been adequately evaluated. The objective of this study was to determine the effect of incorporated composted manure with or without water applications on fumigant emissions and the potential impact on pest control efficacy under field conditions.

Effect of water seal on reducing 1,3-dichloropropene emissions from different soil textures.

Soil physical conditions can affect diffusion, environmental fate, and efficacy of fumigants in soil disinfestation treatments. Water seals (applying water using sprinklers to soil following fumigation) can effectively reduce fumigant emissions from sandy loam soils. Soil column studies compared the effectiveness of water seals in reducing cis-1,3-dichloropropene (1,3-D) emissions from three different textured soils (loamy sand, sandy loam, and loam).

Degradation of methyl iodide in soil: effects of environmental factors.

Methyl iodide (MeI) is a promising alternative to the phased-out fumigant methyl bromide (MeBr); however, there are concerns about its environmental fate following soil fumigation. Laboratory experiments were conducted to investigate the effect of various environmental factors on the rate of MeI degradation in soil. The chemical was added to soil at 48.

Field tests of surface seals and soil treatments to reduce fumigant emissions from shank injection of Telone C35.

A mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) (Telone C35) is an increasingly used fumigant product for pre-plant soil fumigation in California, USA. Atmospheric emissions of volatile organic compounds, including these important pesticides, is more heavily regulated in an effort to improve air-quality. Research has identified various methods of reducing fumigant emissions but effective and economically feasible field methods are still needed.

Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields.

Plastic tarps are commonly used in raised bed strawberry production to minimize emissions of preplant soil fumigants and are left in place throughout the growing season as part of the standard cultural practices. Soil amendments with chemicals such as thiosulfate (S2O3(2-)) can reduce fumigant emissions. A field study was conducted near Santa Maria, CA to determine the effects of low density polyethylene (LDPE) and virtually impermeable film (VIF) over raised-beds and applying potassium thiosulfate (KTS) in furrows on reducing chloropicrin (CP) emissions from a strawberry field.

Thiosulfate and manure amendment with water application and tarp on 1,3-dichloropropene emission reductions.

Reducing fumigant emissions is required for minimizing bystander risk and environmental impact. Effective and economic field management methods including commonly used surface sealing technique and soil amendments are needed for achieving emission reductions. This research determined the effectiveness of ammonium thiosulfate (ATS) and composted manure amendments to surface soil in combination with water application or high density polyethylene (HDPE) tarp on reducing emissions of 1,3-D from soil columns.

Evaluation of fumigation and surface seal methods on fumigant emissions in an orchard replant field.

Soil fumigation is an important management practice for controlling soil pests and enabling successful replanting of orchards. Reducing emissions is required to minimize the possible worker and bystander risk and the contribution of fumigants to the atmosphere as volatile organic compounds that lead to the formation of ground-level ozone. A field trial was conducted in a peach orchard replant field to investigate the effects of fumigation method (shank-injection vs.