Use of Soil Fumigants: Transition from Methyl Bromide to - - PowerPoint PPT Presentation

Use of Soil Fumigants: Transition from Methyl Bromide to Alternatives in California

Suduan Gao* and Larry Wilhoit

2012 PUR Workshop, June 5, Sacramento, CA

• Many crops rely on pre-plant fumigation:
• Strawberry
• Perennials (stone fruits, nuts,

almonds, grapes)

• Annual vegetables (peppers, carrots)
• Nurseries and ornamentals

• Tree and grapevine nurseries need to produce

nematode-free crops (Calif. Dept. of Food and Agriculture Nursery Stock Nematode Control Program)

• Phase-out of methyl bromide
• Montreal Protocol (an international agreement).
• US Clean Air Act
• Official phase out as January 2005; some

allowable uses under CUE and QPS

• Alternatives
• Exposure risks
• VOCs (ozone precursor)
• Regulations by US Environmental Protection Agency

(USEPA) and California Department of Pesticide Regulation (CDPR)

• buffer zone
• township cap
• Low emission requirement in NAAs

Fumigant Issues

California Air Quality Non-Attainment Areas (NAAs)

Segawa, 2008

Important Fumigants

• Methyl bromide (phased out in 2005)
• 1,3-dichloropropene (1,3-D; Telone)
• Chloropicrin
• MITC (methyl isothiocyanate) generators: Metam-sodium

and Metam-potassium

• Methyl iodide (registered, then pulled out in CA)

MeBr: (excellent) fungicide, nematicide, herbicide 1,3-D: (very good) nematicide Chloropicrin: (very good) fungicide and nematicide MITC: (fair) fungicide, nematicide, (nematicide)

Total Fumigant Use

30.8 million lbs in 2009

Total acres of agricultural fields fumigated in California. The total fumigated acres decreased by 27% from 2000 to 2009

Year 1,3-dichloropropene Chloropicrin Metam-K Metam-Na Methyl bromde Total 2000 33,244 68,063 534 146,847 75,839 324,528 2001 30,817 65,166 2,321 125,417 60,892 284,614 2002 42,172 58,907 9,073 141,415 53,140 304,707 2003 48,944 58,460 12,887 142,406 55,254 317,951 2004 56,618 60,932 10,229 128,427 57,385 313,592 2005 51,486 53,797 19,670 97,562 45,700 268,215 2006 49,885 56,129 27,299 102,451 50,677 286,441 2007 53,937 55,678 42,988 78,030 45,675 276,308 2008 57,922 53,964 56,009 71,815 35,685 275,396 2009 38,374 49,639 38,197 74,132 39,587 239,928

Methyl Bromide

Metam sodium and metam potassium

1,3-dichloropropene

Chloropicrin

• California Strawberry (NASS,

2009 report):

• $1.7 billion
• 39,800 acres (69%)
• Total production (88%)
• Rely on soil disinfestation

Fumigant use for strawberry

• Fumigated acreage:

– 50% broadcast shank application – 50% bed drip application

• Tarping with low permeability

tarps (VIF or TIF) is the most effective method to reduce emission, but also most costly, but feasible for strawberry growers.

Fumigation and Emission Reduction Methods

Broadcast (flat) shank application

Drip Application Equipment Drip Application Equipment Drip Application Equipment

Flow meter Static mixer Injection port Water meter Nitrogen cylinder

Chemical name 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 1,3-dichloropropene 13,069 146,636 440,338 884,326 1,523,348 1,596,114 1,660,985 1,903,980 1,791,436 1,129,540 Chloropicrin 2,367,936 3,011,014 2,908,893 3,281,889 3,258,530 3,186,596 3,236,327 3,414,854 3,644,530 3,951,393 Metam-K 31,886 20,247 23,395 79,544 24,207 21,616 11,612 75,797 48,956 Metam-Na 63,108 85,757 238,030 237,943 274,472 226,475 208,823 301,134 188,718 226,713 Methyl bromide 4,257,846 3,777,605 3,706,812 3,676,878 3,190,832 2,929,175 3,083,693 2,688,614 2,710,834 2,516,737 Grand total 6,701,958 7,052,898 7,314,320 8,104,431 8,326,727 7,962,569 8,211,443 8,320,194 8,411,316 7,873,339

Total Annual Use (lbs) of Soil Fumigant for Strawberry Production in CA

2000 2009

?

Physicochemical properties of soil fumigants

Fumigant Molecular formula Molecular weight (g mol-1) Boiling Point (°C) Density (g ml-1) Water solubility (g l-1) Vapor pressure (kPa) KH Methyl bromide Methyl iodide cis-1.3-D trans-1.3-D Chloropicrin MITC Dimethyl disulfide Carbon disulfide CH3Br CH3I C3H4Cl2 C3H4Cl2 Cl3CNO2 CH3NCS C2H6S2 CS2 94.9 141.9 111.0 111.0 164.4 73.1 94.2 76.1 3.6 42.4 104.3 112 112 118-119 110 45.5 1.73 (0 °C) 2.28 (20 °C) 1.22 (20 °C) 1.22 (20 °C) 1.66 (20 °C) 1.05 (24 °C) 1.06 (16 °C) 1.26 (20 °C) 13.4 (25 °C) 14.0 (25 °C) 2.32 (25 °C) 2.18 (25 °C) 1.62 (25°C) 8.2 (25 °C) 4.2 2.94 227 (25°C) 53 (25 oC) 4.5 (25°C) 3.1 (25 oC) 3.2 (25 oC) 2.5 (20 oC) 2.9 (20 oC) 47 (25 oC) 0.24 (20 °C) 0.21 (25 °C) 0.074 (25 °C) 0.043 (25 oC) 0.10 (20 oC) 0.01 (20 oC) 0.05 (20 oC) 0.078 (10 oC)

Research: Reduce emissions & improve efficacy

50 100 150 200 250 300 350

48 96 144 192 240 288 336

Flux (mg/m2/h)

Time (h)

cis 1,3-D trans 1,3-D

20 40 60 80 100 48 96 144 192 240 288 336 Cumulative loss of 1,3-D (% of applied) Time (h)

total 1,3-D

Soil surface treatment Emission reduction potential Cost (excluding fumigant) Other considerations Bare soil The reference level, which

• ften results in >60% emissions
• f total applied fumigant

Labor for preparation of field such as disking and compaction HDPE tarp 0-50% emission reduction depending on soil moisture condition and temperature HDPE: $950-1,100/ac (materials: ~$500/ac; glue, $100/ac; application, $350/ac; cutting and removal, $100/ac) Effective emission reduction in relatively moist soils Low permeable tarps (e.g., VIF) >90% emission reduction if the tarp is installed successfully VIF: $1,200-1,600/ac assuming material cost is 1.5-2x of HDPE and other costs are similar to HDPE Effective emission reduction in almost all conditions; additional time needed for safe removal of the tarp Water treatment 20-50% emission reduction depending on water amount and the number of applications < $300/ac, depending on water price and whether grower owns

• r rents the sprinkler system.

May reduce efficacy at surface soil and additional treatments may be needed Composted manure Not conclusive in reducing emissions at 25 tons/ac composted dairy manure application at maximum Telone rate (330 lbs/ac) Vary depending on application rate and materials costs; Commercial composted manure range: $15-30/ton Consider with free or low cost materials for improving soil properties and emission reduction when fumigant application rate is low Chemicals (e.g., thiosulfate) Potentially >50% emission reduction $150-300/ac at 1:1 to 1:2 fumigant:thiosulfate active ingredient ratio. Excess nutrients or salts to soil; post treatment odor and soil reaction

Summary of emission reduction potential and cost estimates for surface sealing/treatments (Gao et al, 2011, Cal Ag)

Current Research Objectives

Develop field management practices using low permeability tarps (TIF) to reduce emissions, improve efficacy, and reduce fumigant application rates.

Fumigants: 1,3-D; chloropicrin; in various combinations Shallow injection of fumigants (~12 inch deep)

Challenges for perennials

• Requires pest control in deep soils
• Improved fumigant distribution in finer

textured soil:

• TIF tarp
• Carbonation

20 40 60 80 100 5 10 15 20 25 Depth (cm) Average 1,3-D Soil Gas Concentration (µg cm-3)

24 48 120 216 336 505 673 841

HDPE/Full Rate 20 40 60 80 100 5 10 15 20 25 Average 1,3-D Soil Gas Concentration (µg cm-3) TIF/Full Rate

20 40 60 80 100 5 10 15 20 25

TIF/0.25 Rate 20 40 60 80 100 5 10 15 20 25 Depth (cm) TIF/ 0.5 Rate

Summary

• Soil fumigants continue to play important role in the

production of many crops in CA. Fumigant use must comply with environmental regulations for emission reduction while meeting the needs for pest control.

• Fumigant use in a commodity is largely affected by fumigant

registration and costs. Continuous shift in fumigant use is expected.

• Our research is to address the challenges agriculture faces

and seeking solutions to reducing negative impact towards sustainable crop production in CA.