S-Metolachlor Preemergence Herbicide Tank Selection
Metolachlor and S-Metolachlor Preemergence Herbicide — Bulk Tank Selection at Ag-Retailer Distribution, Custom-Applicator Operations, Farmer-Cooperative Stocking, and Row-Crop Production Agriculture
Metolachlor (CAS 51218-45-2; racemic) and S-metolachlor (CAS 87392-12-9; the S-isomer-enriched commercial form) are chloroacetanilide-class selective preemergence herbicides used at corn, soybean, sorghum, cotton, peanut, and a subset of vegetable + sugarbeet row-crop production for control of annual grasses (large + giant + green + yellow foxtail; barnyardgrass; fall panicum; crabgrass; signalgrass; goosegrass; Texas + johnsongrass-seedling; sandbur), small-seeded broadleaves (pigweed species; lambsquarters; nightshade; purslane; carpetweed; galinsoga), and yellow nutsedge. The active ingredient is supplied at 7.62-lb/gal active suspension or emulsifiable concentrate (S-metolachlor 7.62 lb a.i./gal at Syngenta Dual Magnum, Helena Cinch, and post-patent generic equivalents) plus pre-formulated tank-mix premixes including Bicep II Magnum (S-metolachlor + atrazine), Lumax EZ (S-metolachlor + atrazine + mesotrione), and Lexar EZ (S-metolachlor + atrazine + mesotrione). Application timing is preplant-incorporated, preemergence-surface, or early-postemergence at 1.0-2.6 pints per acre depending on soil texture + organic matter + crop tolerance.
U.S. metolachlor + S-metolachlor consumption is concentrated at Syngenta Crop Protection (the Dual Magnum + Bicep II Magnum + Lumax EZ + Lexar EZ branded product family at Greensboro NC technical center), plus generic post-patent supply at Albaugh, Drexel Chemical, ADAMA, FMC, Rotam North America, Sharda Cropchem, and Loveland Products (Helena Agri-Enterprises) house brands. Bulk technical material is manufactured at Syngenta + post-patent global producer plants and shipped at 2,500-gallon stainless or HDPE tote + 250-gallon shuttle + 30-gallon drum to U.S. ag-retailer + farmer-cooperative + custom-applicator stocking points. Storage envelope at ag-retail + co-op + custom-applicator: 7.62-lb-a.i./gal S-metolachlor formulated product is buffered at HDPE atmospheric stainless-jacketed tank in the 1,000-6,000 gallon range serving spring-season custom-applicator dispensing + farmer pickup + field-tender reload.
The eight sections below cite EPA FIFRA registration framework for chloroacetanilide herbicides, Federal Insecticide Fungicide and Rodenticide Act 7 USC 136 et seq. labeling and tolerance compliance, EPA OPP Reregistration Eligibility Decision (RED) for metolachlor and the metolachlor + S-metolachlor stewardship program, OSHA Worker Protection Standard 40 CFR Part 170 agricultural-worker reentry framework, ASABE / ASAE S472 + S327 + S386 sprayer-calibration and ground-application standards, EPA Endangered Species Act Bulletins Live framework and county-by-county pesticide use limitations, state-DEP groundwater-monitoring programs (Wisconsin, Minnesota, Iowa, Nebraska, Kansas, Texas, California Central Valley), USDA NRCS conservation-practice standards (Code 595 Pest Management Conservation System), ASTM D6692 + D6754 polyethylene tank specifications, and routine operating practice at North American ag-retail + co-op + custom-applicator + farm-cooperative distribution + handling.
1. Material Compatibility Matrix
Formulated S-metolachlor 7.62-lb-a.i./gal product is a brown-amber emulsifiable concentrate or oil-in-water suspension at pH 5.5-7.5, containing the active ingredient plus aromatic petroleum solvent + nonionic emulsifier surfactant + antifreeze + antifoam at typical formulation. The petroleum solvent + emulsifier package is the dominant material-compatibility driver at HDPE storage; the active itself is mild at typical contact time but the solvent system requires careful gasket + seal selection.
| Material | S-Metolachlor 7.62 lb/gal EC | Aqueous tank-mix (1-3% v/v) | Notes |
|---|---|---|---|
| HDPE rotomolded | A | A | Standard at ag-retail + co-op atmospheric storage; full envelope at 7.62-lb formulation; UV-stabilized exterior recommended at outdoor service |
| XLPE rotomolded | A | A | Equivalent to HDPE; preferred at premium installations |
| Polypropylene (PP) | A | A | Acceptable at fittings + valves + tank-mix mini-bulk service |
| PVDF (Kynar) | A | A | Premium dosing-pump diaphragm + tubing service |
| PVC Sch 80 | B | A | Acceptable at piping; aromatic solvent slowly attacks PVC at long quiescent contact; CPVC preferred |
| CPVC Sch 80 | A | A | Preferred at piping over PVC due to better aromatic-solvent resistance |
| FRP (vinyl ester) | A | A | Acceptable at large bulk storage; less common than HDPE at ag retail |
| 304L stainless steel | A | A | Premium tote + shuttle + bulk-receiving tank service |
| 316L stainless steel | A | A | Premium fittings + valves + transfer-pipe service |
| EPDM | D | C | NOT acceptable at concentrated formulation; aromatic solvent rapidly swells EPDM; do not use at gaskets or hoses |
| Viton (FKM) | A | A | Standard gasket + flexible-hose service at chloroacetanilide formulation; full envelope |
| Buna-N (Nitrile) | B | A | Acceptable at most service; aromatic solvent slow-swell at long contact |
| PTFE / Teflon | A | A | Premium gasket + valve-seat service; full envelope |
| Polyurethane | D | C | NOT acceptable at concentrated formulation; aromatic solvent attacks polyurethane |
| Carbon steel (uncoated) | C | B | Acceptable short-term at sealed tote + shuttle service; epoxy-lined preferred at long-term |
| Aluminum | C | B | Acceptable at sprayer tank service; not preferred at long-term bulk storage |
The dominant industrial pattern at North American ag-retailer + farmer-cooperative + custom-applicator S-metolachlor storage is HDPE rotomolded vertical atmospheric tank in the 1,000-6,000 gallon range with CPVC + Viton + PTFE wetted plumbing + stainless-steel fittings + air-operated diaphragm transfer pump. OneSource Plastics' 5-brand HDPE network (Norwesco, Snyder Industries, Chem-Tainer, Enduraplas, Bushman) is the standard atmospheric storage platform at ag-retail + co-op chloroacetanilide herbicide distribution.
2. Real-World Industrial Use Cases
Ag-Retailer + Cooperative Bulk Stocking and Mini-Bulk Loadout. Independent ag-retailers (Helena Agri-Enterprises, Wilbur-Ellis, Nutrien Ag Solutions, Simplot Grower Solutions, GROWMARK FS member cooperatives, CHS Inc., Land O'Lakes Truterra/WinField United, plus regional co-ops) operate retail-distribution facilities receiving bulk + mini-bulk + tote S-metolachlor at 1,000-6,000 gallon HDPE atmospheric tank, dispensing to grower mini-bulk tote + 30-gallon drum + sprayer field-tender via metering pump + closed-system handling per EPA Pesticide Container Containment Rule (40 CFR Part 165 Subpart E) refillable-container requirements.
Custom-Applicator Spring-Season Operations. Custom application services (corn-belt + soybean-belt + cotton-belt regional applicator networks; Helena Custom App, Wilbur-Ellis Custom App, Nutrien Custom App, plus thousands of independent custom-applicator businesses) maintain 1,000-3,000 gallon HDPE day-tank stocking S-metolachlor at primary custom-applicator branch + nurse-truck mini-bulk + sprayer-tender refill operations during the spring preplant + preemergence application window (typically March through June across U.S. row-crop geography).
Farmer-Cooperative Tank-Mix Premix Bulk Stocking. Pre-formulated premix products (Bicep II Magnum + Lumax EZ + Lexar EZ at Syngenta; generic post-patent S-metolachlor + atrazine premix at Albaugh + Drexel + Helena + Loveland) ship at 2,500-gallon mini-bulk and 30-gallon drum from formulator plant to co-op + ag-retailer; cooperative bulk storage at 2,000-6,000 gallon HDPE tank serves grower mini-bulk + sprayer-tender refill at the same spring-season window.
Vegetable + Sugarbeet Production Specialty Use. Specialty preemergence S-metolachlor application at sugarbeet (Michigan, Minnesota, North Dakota, Idaho, Wyoming), potato (Idaho, Washington, Wisconsin, Maine, North Dakota), pumpkin + watermelon + cucurbit, and snap bean production relies on smaller-scale bulk + tote stocking at regional vegetable-belt ag-retail + co-op operations; HDPE 500-1,500 gallon vertical tank is the standard at vegetable-belt service.
Aerial-Application Service Centers. Aerial-applicator service centers (helicopter + fixed-wing ag-aviation operators across the corn + cotton + sugarcane + rice belt) load S-metolachlor at 200-1,000 gallon HDPE day-tank at the aerial-loading pad with closed-transfer + dye-injection + nozzle-purge to prevent off-target drift + worker exposure per EPA + state-aerial-applicator + FAA Part 137 framework.
State Department of Agriculture Pesticide Storage Permit Compliance. Bulk pesticide storage (typically >500 gallons aggregate at single facility) triggers state-DEP + state-DOA pesticide-storage-permit requirements (Wisconsin DATCP ATCP 33, Iowa DALS 21-44.6, Minnesota MDA 1505, Nebraska NDA 33, Kansas KDA pesticide-storage-secondary-containment, Indiana OISC 357 IAC 1-5, Illinois IDA 8 IAC 250) imposing secondary-containment + spill-response + employee-training requirements; HDPE atmospheric storage with engineered HDPE secondary-containment pan or concrete-bermed pad is the dominant compliance solution.
3. Regulatory Framework
EPA FIFRA Registration. Metolachlor was federally registered at EPA in 1976; S-metolachlor at EPA in 1997. Both are Restricted Use Pesticide-eligible at certain state-specific designations (Texas RUP for groundwater-protection counties; California limited-use status at certain restricted-use-permit-required counties) but are not blanket federally-restricted at the FIFRA Section 3 registration. Product labels detail use-rate, crop, geographic, and reentry specifications under FIFRA 7 USC 136 enforcement framework.
EPA OPP RED + Stewardship Program. EPA Office of Pesticide Programs published the metolachlor Reregistration Eligibility Decision (RED) in 1995, supplemented by ongoing registration review. EPA + Syngenta operate an industry stewardship program addressing groundwater detection of metolachlor + the metolachlor metabolite oxanilic acid (OA) and ethanesulfonic acid (ESA) at vulnerable aquifers across the U.S. Midwest and Atlantic Coastal Plain.
40 CFR Part 165 Pesticide Container Containment Rule. EPA's bulk-pesticide-storage rule requires impervious secondary containment at refillable-container bulk-pesticide-storage facilities at 500-gallon-aggregate threshold, with detailed specifications for containment-pad volume (sufficient to capture largest single tank plus precipitation), surface impermeability, and inspection-recordkeeping requirements. HDPE bulk + mini-bulk pesticide handling at ag-retailer + co-op falls under this rule.
OSHA Worker Protection Standard 40 CFR Part 170. Reentry interval for treated fields is 24 hours under standard application; protective-equipment requirements at handler include long-sleeve shirt + long pants + chemical-resistant gloves (Viton, butyl, or PTFE) + chemical-splash goggles + closed-toe footwear + chemical-resistant apron at mixing-loading + open-system handling. WPS posting + hazard communication + worker training are required at agricultural establishments.
EPA Endangered Species Act Bulletins Live. S-metolachlor + atrazine premix + tank-mix application is subject to county-by-county Endangered Species Act use limitations published at EPA's Bulletins Live! Two system; applicators are required to consult Bulletins Live! at point of application for active geographic restrictions protecting listed aquatic + terrestrial species.
State Groundwater Monitoring Programs. Wisconsin DATCP, Minnesota MDA, Iowa DNR, Nebraska DEE, Kansas KDHE, and California DPR operate ongoing groundwater-monitoring programs detecting metolachlor + metolachlor-OA + metolachlor-ESA at vulnerable aquifers; state-specific use limitations + groundwater-protection-area + setback restrictions are imposed at high-detection counties (e.g. Wisconsin Atrazine Prohibition Areas, certain Iowa karst counties, certain California Central Valley districts).
USDA NRCS 595 Pest Management Conservation Practice. Federal cost-share + crop-insurance benefits at NRCS Conservation Practice Code 595 Pest Management Conservation System encourage IPM-based herbicide management with reduced-rate + banded + post-emergent + biological-alternative practices reducing total chloroacetanilide load to vulnerable watersheds.
4. Storage System Specification
Bulk-Storage Tank. S-metolachlor 7.62-lb-a.i./gal formulated product bulk storage at HDPE rotomolded 1,000-6,000 gallon scale: standard HDPE resin per ASTM D1248 specification; vertical flat-bottom or conical-bottom vessel; 4-inch ANSI flanged top fill or 3-inch threaded top at smaller sizes; 3-inch flanged bottom outlet with PVC or CPVC ball valve; atmospheric vent with insect-screen + dust-cover; 18-24-inch top manway for inspection + cleaning access; ultrasonic or radar level transmitter with high-high alarm + low-low alarm; sample valve at 12 inches above bottom outlet for QC sampling; HDPE bulkhead fittings at all penetrations rated for 1.10-1.15 SG (S-metolachlor 7.62-lb formulation approx 1.10 SG) and 100 deg F maximum service temperature; UV-stabilized exterior + UV-resistant cap at outdoor installations.
Secondary Containment per 40 CFR Part 165. Bulk + mini-bulk pesticide storage at 500-gallon aggregate threshold requires impervious secondary containment with capacity equal to 100% of largest single vessel plus precipitation (typically 110% of largest tank). HDPE secondary-containment pan, concrete-bermed pad with chemical-resistant coating, or steel-framed concrete-walled containment basin are standard. Drainage connection requires positive isolation valve + lockable manual-only drain to prevent unintended contaminated-rainfall release.
Closed-Transfer System. EPA + state-DOA closed-system transfer requirements at refillable-container service eliminate operator exposure during transfer; HDPE bulk tank dispenses through dry-disconnect coupler (Banjo Corp dry-disconnect, Dixon DC-Series, Walther Praezision dry-disconnect) to grower mini-bulk + sprayer-tender via metering pump; air-operated diaphragm pump (Wilden M4, Aro Ingersoll-Rand, SandPiper, Yamada) at 8-25 gpm transfer rate is standard.
Heat-Tracing + Freeze-Protection. S-metolachlor formulation viscosity rises and emulsion stability degrades below 32 deg F; northern-corn-belt + sugarbeet-belt + Canadian-prairie installations require heated + insulated storage building (typically conditioned to 50-65 deg F) or heat-traced + insulated bulk tank to maintain product stability through winter dormant storage. Self-regulating electric heat-trace cable + 2-inch closed-cell polyurethane insulation is the standard cold-weather package.
Spill-Response Equipment. Pesticide-bulk-storage facilities maintain on-site spill-response kit per state-DOA + 40 CFR Part 165 framework: absorbent pad + sock + boom; HDPE drum for contaminated absorbent collection; PPE (Viton gloves, splash goggles, Tyvek suit, half-face respirator with organic-vapor cartridge); spill-response written procedure + emergency-contact list; state-DEP + EPA National Response Center + state-911 + Syngenta technical-emergency-line (1-800-888-8372 SyngentaPro Hotline) phone numbers posted at storage facility.
5. Field Handling Reality
Handler PPE. Mixer-loader-applicator PPE per S-metolachlor product label: long-sleeve shirt + long pants + chemical-resistant gloves (Viton, butyl, or PTFE; do not use EPDM or natural rubber due to aromatic-solvent permeation) + chemical-splash goggles + closed-toe footwear + chemical-resistant apron at mixing-loading. Closed-system handling per WPS engineering-control reduces PPE to long-sleeve shirt + long pants + chemical-resistant gloves at certain rate-and-task combinations.
Tank-Truck Receipt + Mini-Bulk Transfer. Bulk S-metolachlor delivery is by 5,500-7,000 gallon DOT-406 stainless tanker (formerly MC-306) at large ag-retailer + co-op; smaller volume by 1,000-2,500 gallon mini-bulk tote. Tanker offload via plant-side air-operated diaphragm transfer pump at 25-100 gpm transfer rate; transfer pipe is 2-3 inch CPVC or stainless + camlock or dry-disconnect + manual ball-valve isolation. Driver continuous attendance per DOT 49 CFR 177.834; high-level shutoff via float switch + radar level + tanker safety-stop.
Sampling + Quality Control. Each tanker delivery requires sample collection at receipt for internal QC + supplier-COA verification: active ingredient content by HPLC (Syngenta + post-patent generic CofA reference), water content by Karl Fischer titration, pH by glass electrode at 1% aqueous, density at 20 deg C by hydrometer, color + clarity + emulsion stability at standard agitation. Records retained 2-3 years for state-DOA audit + customer-quality-complaint traceability.
Spill Response. S-metolachlor is FIFRA-regulated environmental-hazard product. Spill response: contain to floor + secondary containment, sweep liquid via wet-vac or absorbent pad + sock to HDPE drum, neutralize residual via large-volume rinse to closed-loop holding tank for licensed disposal at hazardous-waste-treatment-storage-disposal facility (typically Clean Earth, Veolia, Heritage, Stericycle, or regional equivalent). State DEP + EPA National Response Center notification at any spill exceeding RQ (Reportable Quantity is 100 lb metolachlor per CERCLA); state-DOA notification at any incident-of-concern.
Tank Cleaning + Inspection. Annual tank inspection + recertification per facility 40 CFR Part 165 + state-DOA framework: drain to recovery tank, triple-rinse with potable water + ammonia or alkaline cleaner, neutralize rinse waste at on-site holding for licensed disposal, inspect interior for residue + crystallization at fill-line + outlet, refill at next campaign. Confined-space entry per OSHA 29 CFR 1910.146 with atmospheric monitoring + supplied-air respiratory protection at any internal inspection.
Compatibility with Other Pesticide Storage. S-metolachlor storage should NOT be co-located with strong oxidizers (calcium hypochlorite, sodium hypochlorite, hydrogen peroxide, peracetic acid), strong acids, or strong bases at adjacent secondary containment. Dedicated chloroacetanilide storage at separate containment + clear labeling prevents cross-contamination + worker confusion.
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