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)

Fumigant Issues • 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

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

Fumigant use for strawberry • California Strawberry (NASS, 2009 report): • $1.7 billion • 39,800 acres (69%) • Total production (88%) • Rely on soil disinfestation

Broadcast (flat) shank application Fumigation and Emission Reduction Methods • Fumigated acreage: – 50% broadcast shank application – 50% bed drip application • Tarping with low permeability Drip Application Equipment Drip Application Equipment Drip Application Equipment tarps (VIF or TIF) is the most effective method to reduce Flow meter emission, but also most costly, but feasible for strawberry growers. Nitrogen cylinder Injection Water port meter Static mixer

Total Annual Use (lbs) of Soil Fumigant for Strawberry Production in CA 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 2009 2000 ?

Physicochemical properties of soil fumigants Fumigant Molecular Molecular Boiling Density Water Vapor K H (g ml -1 ) formula weight Point solubility pressure (g mol -1 ) (g l -1 ) (°C) (kPa) Methyl bromide CH 3 Br 94.9 3.6 13.4 (25 °C) 227 (25°C) 0.24 (20 °C) 1.73 (0 °C) Methyl iodide CH 3 I 141.9 42.4 2.28 (20 °C) 14.0 (25 °C) 53 (25 o C) 0.21 (25 °C) cis-1.3-D C 3 H 4 Cl 2 111.0 104.3 1.22 (20 °C) 2.32 (25 °C) 4.5 (25°C) 0.074 (25 °C) 3.1 (25 o C) 0.043 (25 o C) trans-1.3-D C 3 H 4 Cl 2 111.0 112 1.22 (20 °C) 2.18 (25 °C) 3.2 (25 o C) 0.10 (20 o C) Chloropicrin Cl 3 CNO 2 164.4 112 1.66 (20 °C) 1.62 (25°C) MITC CH 3 NCS 73.1 118-119 8.2 (25 °C) 2.5 (20 o C) 0.01 (20 o C) 1.05 (24 °C) Dimethyl disulfide C 2 H 6 S 2 94.2 110 1.06 (16 °C) 4.2 2.9 (20 o C) 0.05 (20 o C) 47 (25 o C) 0.078 (10 o C) Carbon disulfide CS 2 76.1 45.5 1.26 (20 °C) 2.94

Research: Reduce emissions & improve efficacy 100 350 Cumulative loss of 1,3-D (% of applied) 300 80 cis 1,3-D total 1,3-D trans 1,3-D 250 Flux (mg/m 2 /h) 60 200 150 40 100 20 50 0 0 0 48 96 144 192 240 288 336 0 48 96 144 192 240 288 336 Time (h) Time (h)

Summary of emission reduction potential and cost estimates for surface sealing/treatments (Gao et al, 2011, Cal Ag) Soil surface Emission reduction potential Cost (excluding fumigant) Other considerations treatment Bare soil The reference level, which Labor for preparation of field such often results in >60% emissions as disking and compaction of total applied fumigant 0-50% emission reduction HDPE: $950-1,100/ac (materials: Effective emission reduction in HDPE tarp depending on soil moisture ~$500/ac; glue, $100/ac; relatively moist soils condition and temperature application, $350/ac; cutting and removal, $100/ac) >90% emission reduction if the VIF: $1,200-1,600/ac assuming Effective emission reduction in Low permeable tarps (e.g., VIF) tarp is installed successfully material cost is 1.5-2x of HDPE almost all conditions; and other costs are similar to additional time needed for safe HDPE removal of the tarp 20-50% emission reduction < $300/ac, depending on water May reduce efficacy at surface Water treatment depending on water amount price and whether grower owns soil and additional treatments and the number of applications or rents the sprinkler system. may be needed Composted Not conclusive in reducing Vary depending on application Consider with free or low cost manure emissions at 25 tons/ac rate and materials costs; materials for improving soil composted dairy manure Commercial composted manure properties and emission application at maximum Telone range: $15-30/ton reduction when fumigant rate (330 lbs/ac) application rate is low Chemicals (e.g., Potentially >50% emission $150-300/ac at 1:1 to 1:2 Excess nutrients or salts to thiosulfate) reduction fumigant:thiosulfate active soil; post treatment odor and ingredient ratio. soil reaction

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 Average 1,3-D Soil Gas Concentration (µg cm -3 ) Average 1,3-D Soil Gas Concentration (µg cm -3 ) 0 5 10 15 20 25 0 5 10 15 20 25 0 0 HDPE/Full Rate TIF/Full Rate 24 20 20 48 Depth (cm) 120 40 40 216 336 60 60 505 673 80 80 841 100 100 0 5 10 15 20 25 0 5 10 15 20 25 0 0 TIF/0.25 Rate TIF/ 0.5 Rate 20 20 Depth (cm) 40 40 60 60 80 80 100 100

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.