Ammonium Nitrate Storage — Fertilizer Solution & Regulatory Reality

Four Facts That Shape AN Tank Design

Every ammonium nitrate storage decision starts with four regulatory and chemistry facts:

1. CFATS-regulated above 200 lbs solid or 400 lbs solution. DHS Chemical Facility Anti-Terrorism Standards (6 CFR Part 27) requires Top-Screen submission for any facility storing over the 200-lb solid / 400-lb solution threshold. Solution storage in a 55-gallon drum at 20% AN concentration is roughly 85 lbs AN — below threshold. A 1,500-gallon tank at the same concentration is 2,340 lbs — fully regulated.
2. ATF Explosives and Incendiary Devices tracking. Under 27 CFR 555, ammonium nitrate is a "listed explosive material precursor" above certain quantities. Sale tracking, user licensing, and inventory documentation apply.
3. State-level fertilizer-inspection registration. Every state ag department has rules on bulk-fertilizer storage and sale. Texas Feed and Fertilizer Control Service (TFFCS at Texas A&M), Iowa Department of Ag, California Department of Food and Agriculture — separate registration, separate fees, separate inspections.
4. NFPA 400 and 495 codes. National Fire Protection Association chemical-storage standards apply. Separation distances, containment, and prohibited co-storage (especially with organic fuels and strong acids) are spelled out.

The tank itself is straightforward. The paperwork is where installations succeed or fail. This pillar covers both — tank spec first, then the compliance landscape.

MOC Stack — Saturated Solution

Enduraplas rates saturated ammonium nitrate as Satisfactory in HDPE and LDPE/MDPE at 70°F and 140°F. The MOC stack:

• Resin: HDPE or XLPE
• Specific Gravity: 1.5 ASTM (saturated 70% AN solution density is 1.43 g/mL)
• Fittings: PVC, CPVC, or polypropylene
• Gaskets: EPDM or Viton — both compatible. EPDM is industry default for fertilizer service.
• Bolts: 316SS

Agricultural UAN (urea-ammonium-nitrate liquid fertilizer) and straight ammonium-nitrate solution both fit this spec. The dominant liquid AN product is UAN-28 or UAN-32 (28% or 32% nitrogen, with AN and urea split roughly 50/50). The pure-AN solution market exists but is smaller than the blended UAN market because UAN's chemistry is more cold-stable.

Agricultural Fertilizer Service — UAN and Pure AN

Row-crop agriculture (corn, wheat, cotton, sorghum, rice) is the dominant market for liquid nitrogen fertilizer. Application methods:

• Pre-plant broadcast: sprayer rigs applying 20–40 gallons per acre of UAN-32 or UAN-28 to the soil surface before tillage.
• Side-dress: planters equipped with liquid-fertilizer applicators dropping UAN into bands alongside the crop row at emergence.
• Fertigation: injection into center-pivot or drip-irrigation water. Common on irrigated corn in Nebraska, Kansas, Colorado; common on cotton in Texas High Plains.

A grain-farm fertilizer tank runs 1,500–6,000 gallons at the farm headquarters, plus a trailer-mounted 1,000-gallon applicator tank. A commercial ag-retail fertilizer plant (CPS, Nutrien, local co-op) runs 20,000–200,000 gallons of UAN inventory during spring application season.

Pure ammonium-nitrate solution (not blended with urea) is less common at farm scale. Some cotton and corn operations prefer it because AN nitrogen is immediately plant-available (vs urea which must hydrolyze first). Specialty vegetable farms also use pure AN for quick-response fertilization.

CFATS Compliance — The Top-Screen Process

DHS Chemical Facility Anti-Terrorism Standards require Top-Screen submission for any facility storing above threshold quantities of listed chemicals. For ammonium nitrate, the thresholds are 200 lbs solid or 400 lbs in solution. Top-Screen is a web-based submission at the DHS Chemical Security Assessment Tool (CSAT) portal.

Based on Top-Screen results, DHS may classify the facility as "high-risk" (Tier 1–4) or confirm it as exempt. High-risk facilities complete a Security Vulnerability Assessment (SVA) and a Site Security Plan (SSP), each with DHS review and approval.

Practical impact for a typical mid-size fertilizer dealer:

• Top-Screen once at initial threshold crossing
• Update when storage quantities or facility layout change significantly
• Tier designation determines whether on-site inspection, cyber-security standards, and personnel-surety program apply

The National Fertilizer Solutions Association and The Fertilizer Institute publish industry guides. State ag-retail associations (Texas Ag Industries Association, Iowa Agribusiness Retailers Association) provide compliance training.

Separation and Co-Storage — What You Can't Put Next to AN

NFPA 400 (Hazardous Materials Code) and NFPA 495 (Explosive Materials Code) specify separation distances between ammonium nitrate storage and other materials. Prohibited or restricted co-storage:

• Organic fuels — diesel, gasoline, oil, grease. AN + organic fuel is the ANFO chemistry. Any warehouse storing both needs walls, distance separation, and fire-break design.
• Strong acids — sulfuric, nitric, HCl. Contact with strong acids releases NOx gases and creates thermal-runaway risk.
• Chlorates and chlorides — decomposition catalysts that can lower the thermal-runaway threshold.
• Combustible organic materials — seed cotton, hay bales, peat moss. Listed specifically in NFPA 400.
• Heat sources — unattended space heaters, electrical panels subject to arcing, welding operations.

Typical site design: AN storage in a dedicated building, concrete-walled, noncombustible roof, minimum 25-50 ft separation from fuel storage and main warehouse. Texas TFFCS, Iowa Ag Department, and state fire marshals publish specific siting rules.

Post-West-Fertilizer Regulatory Changes

The April 2013 fertilizer-plant fire and explosion in West, Texas (15 deaths, 160+ injured, widespread damage) triggered federal and state regulatory reviews. Key changes since:

• EPA Risk Management Program (RMP) amendments — facilities storing reactive chemicals above threshold must develop and implement accident-prevention programs.
• OSHA Process Safety Management (PSM) coverage expansion — ammonium nitrate operations above threshold now fall under PSM requirements for highly hazardous chemicals.
• Local Emergency Planning Committee (LEPC) notifications — EPCRA Tier II reporting at lower thresholds; better integration with fire-department pre-incident planning.
• Texas HB 942 (2015) — state fire-marshal authority over ammonium-nitrate storage, minimum distance requirements, fire-code enforcement.

For a typical agricultural tank installation, these changes manifest as: more paperwork, better fire-department communication, clearer separation requirements, and mandatory LEPC notification. The underlying fertilizer business continues; the compliance overhead is real.

Industrial and Blasting Applications — Regulated Market

Outside agriculture, ammonium nitrate is used in:

• Mining and quarrying: ANFO (ammonium nitrate fuel oil) and emulsion blasting agents. ATF-licensed users only. Solid AN storage in bulk silos; solution storage primarily at manufacturing facilities, not mine sites.
• Industrial nitrous oxide production: AN thermal decomposition yields N2O for medical, dental, and semiconductor applications.
• Instant cold packs and chemistry-demonstration kits: small-quantity AN in endothermic dissolution applications. Below any regulatory threshold.

Industrial-use tank storage follows the same MOC stack but with more stringent compliance overhead. Mining facilities typically use FRP or stainless over polyethylene because of scale and fire-rating requirements.

Concentration-Band Compatibility (Enduraplas / Equistar Data)

Polyethylene chemical resistance by concentration and service temperature. Satisfactory (S) = long-term service. Limited (O) = occasional only. Unsatisfactory (U) = do not use.

Frequently Asked Questions

Can I buy ammonium nitrate solution without ATF licensing?

For agricultural use below threshold quantities, yes — farm-scale purchases of UAN-32 through co-ops or ag retailers don't require ATF explosives licensing. For bulk quantities that cross CFATS or ATF precursor thresholds, registration applies. Most retail-level farmers never hit the threshold; commercial fertilizer dealers always do. Check with your supplier — they track the paperwork on behalf of customers.

Does AN solution freeze in winter storage?

UAN-32 freezes around 28°F; UAN-28 freezes around 1°F. Pure AN solutions freeze higher depending on concentration. In northern climates, most fertilizer storage is emptied and flushed in fall, refilled in spring. Year-round storage requires insulation and heat-tracing, or switching to a lower-freeze-point product. The crystallization on freezing is not a safety issue but it renders the tank unusable until thaw.

Why do I need to tell the fire department about my AN tank?

EPCRA Tier II and LEPC reporting. Emergency Planning and Community Right-to-Know Act (42 USC 11021) requires chemical-inventory reporting to the State Emergency Response Commission and the Local Emergency Planning Committee annually for any facility above reportable quantities. For AN, the reportable quantity is 10,000 lbs under EHS (Extremely Hazardous Substance) status. Below that, Tier I reporting still applies at lower thresholds. Your fire department pre-incident plan uses this data to respond correctly to any incident.

Can I store UAN-32 in a used urea-solution tank?

Yes — both are benign to HDPE, gaskets and fittings compatible, cross-contamination non-issue (urea and AN blend cleanly, in fact UAN IS a urea-AN blend). What you need to verify: tank SG rating (1.5 ASTM for UAN-32's denser chemistry) and fitting sizes for your application equipment. Repurposing a used tank is standard in ag.

Does secondary containment have to be concrete?

State and local fire codes vary. Concrete works but spalls under AN spill exposure over years — epoxy-coated or HDPE-lined concrete is preferred for long-term installations. Earthen berms with HDPE liner work in rural agricultural installations where containment volume is large. Steel containment basins are uncommon for AN service due to corrosion concerns.

Is solution AN an OSHA PSM-covered process?

Above 10,000 lbs of reactive chemical, yes. PSM 29 CFR 1910.119 applies, with mechanical integrity, process hazard analysis, employee training, and incident investigation requirements. For typical farm-scale storage (1,500–3,000 gallons = 4,500–9,000 lbs), PSM doesn't apply. Commercial ag-retail facilities storing 50,000+ gallons are fully covered. The compliance overhead is substantial — budget accordingly if you're scaling up.

Source Citations

• Snyder Industries — Chemical Resistance Recommendations (current edition)
• Enduraplas / Equistar Technical Tip — Chemical Resistance of Polyethylene (12-page reference)

Ammonium Nitrate Compatibility Matrix — Regulated Fertilizer and Oxidizer Service

Ammonium nitrate (NH₄NO₃) is a high-nitrogen, highly soluble, strongly oxidizing salt and the most volume-regulated fertilizer chemistry in the United States. It is sold as prilled 34-0-0 solid fertilizer, as 83% aqueous UAN-component solution, and as industrial-grade emulsion for mining explosives (ANFO — ammonium nitrate fuel oil). The 2013 West Fertilizer Company warehouse fire in West, Texas killed 15 people (including 12 first responders), destroyed surrounding housing, and injured roughly 270 workers and residents — it fundamentally reshaped US ammonium nitrate regulation. Storage and bulk handling are now governed by DHS Chemical Facility Anti-Terrorism Standards (CFATS) as a Chemical of Interest with 2,000 lb registration threshold, NFPA 400 Chapter 11 prescriptive design requirements, OSHA Process Safety Management (PSM) coverage above 15,000 lb, and state fertilizer-inspection regimes with prescriptive segregation and containment rules. Despite the regulatory burden, polyethylene storage is perfectly appropriate for the solution form — HDPE and XLPE are A-rated across the full concentration range for aqueous NH₄NO₃ in the absence of organic contamination. Prilled solid ammonium nitrate is never stored in polyethylene tanks — solid bulk storage follows NFPA 400 Chapter 11 warehouse specifications with non-combustible construction and no concealed organic fuel sources. The matrix below covers solution storage. "S" = Satisfactory, "L" = Limited, "U" = Unsatisfactory.

The specification rule: XLPE or HDPE with 1.9+ SG rating is the default material for ammonium nitrate solution below 140°F, and 316L stainless is the alternative for elevated-temperature service and for integrated UAN blend systems where solution crystallization risk requires heat-tracing. Aluminum is strictly prohibited — ammonium nitrate attacks aluminum violently, particularly at elevated temperature, and the reaction has contributed to documented storage fires. Carbon steel is unsuitable for long-term wetted service due to corrosion and the catalytic role Fe⁺⁺⁺ ions play in accelerating NH₄NO₃ thermal decomposition. Vinyl-ester FRP is acceptable for solution storage but rarely specified because polyethylene handles the service at lower cost. The absolute prohibition in any ammonium nitrate storage tank is organic contamination: no wooden pallets in the tank area, no fuel-oil spills near the tank, no sawdust or cellulosic fiber, and no rubber hose accumulated in a spill pan. The fuel-oxidizer combination is the core hazard mechanism that created ANFO as a mining explosive and that drove the West Texas disaster.

Real-World Industrial Use Cases

US ammonium nitrate consumption splits across three major verticals, each with distinct handling and storage regimes driven by federal regulation:

• Direct-application fertilizer (solid prilled 34-0-0): Historically the largest use but declining since the 2013 West Texas disaster and subsequent regulatory tightening. Solid AN is still applied in wheat, pasture, and specific row-crop regions where ammonium sulfate and urea alternatives don't fit agronomically. Warehouse storage is NFPA 400 Chapter 11 compliant: non-combustible building construction, no wooden mezzanines or pallets in contact with product, pile-size limits, isolation from organic fuels, and fire-service pre-plan with full-facility access and unlimited-water supply requirements. State fertilizer-inspection agencies (Texas TCEQ, Minnesota Department of Agriculture, etc.) conduct annual compliance audits.
• UAN solution blending (32% liquid nitrogen fertilizer): The largest liquid application. UAN 32% is blended at fertilizer terminals from 83% ammonium nitrate solution and 72% urea solution in roughly equal nitrogen contribution. Terminal-scale blending facilities store 50,000–500,000 gallons of 83% AN solution in 316L stainless or specialty-coated carbon-steel tanks (heat-traced to prevent crystallization below 32°F eutectic for 83% solution). Farm-scale bulk holding of finished UAN 32% uses 5,000–30,000 gallon XLPE or HDPE vertical flat-bottom tanks with 1.9+ SG rating.
• Mining explosives (ANFO precursor): Industrial-grade porous prilled AN is shipped to mining sites and blended with 5.7–6.0% diesel fuel oil on-site to produce ANFO for open-pit coal, copper, gold, and aggregate quarry blasting. Volume is concentrated at a small number of industrial manufacturers (Dyno Nobel, Orica, Austin Powder) with BATF (ATF) Type 20 explosives-manufacturing licensure. Bulk silo and warehouse storage is regulated under ATF 27 CFR 555 in addition to CFATS and NFPA 400.
• Sports instant cold packs: Tiny volume niche. Small-format AN packets surrounded by water-bladder; breaking the bladder dissolves AN and produces endothermic cooling. Not relevant to bulk tank storage.
• Nitrous oxide production: Specialty chemical feedstock for N₂O production (medical and automotive propellant). Pharmaceutical-grade AN handled in small-volume 316L stainless vessels.

A standardized farm-scale UAN-32 configuration is a 10,000–15,000 gallon XLPE or HDPE vertical flat-bottom tank rated 1.9 SG, 3" bottom outlet, polymer-bodied bulkhead and threaded fittings, atmospheric vent, and secondary containment sized to 110% of tank volume. Total installed cost is $10,000–$18,000 depending on region. UAN 32% has a specific gravity of 1.32 and a crystallization point of +32°F for 32% (the naming trick), which means farm-scale storage in unheated locations in USDA cold zones needs winter tank-blanket heat trace or partial-fill management. The federal registration trigger: farm-scale UAN tanks hold finished 32% product which contains about 40% ammonium nitrate by weight; the DHS CFATS 2,000 lb AN threshold is reached at approximately 600 gallons of UAN 32%. Most farm bulk-holding tanks therefore exceed the registration threshold and require CFATS Top-Screen submission and site-security plan compliance.

Hazard Communication — GHS, NFPA 704, DOT, Regulatory

CAS: 6484-52-2. UN: 1942 (solid, 5.1 oxidizer), UN2067 (fertilizer grade solid), UN2426 (molten). TSCA: listed, active. EINECS: 229-347-8.

• GHS pictograms: Flame over circle (oxidizer), Exclamation mark (irritant). Signal word: Danger.
• GHS hazard statements: H272 (may intensify fire; oxidizer), H319 (eye irritation), H335 (respiratory irritation).
• NFPA 704: Health 2, Flammability 0, Instability 3, Special: OX (strong oxidizer).
• DOT hazard class: Division 5.1 (oxidizer) — placarded shipment required above reportable quantity.
• EPA CERCLA RQ: not a CERCLA listed hazardous substance but regulated extensively under SARA 302 (Extremely Hazardous Substance threshold planning quantity 10,000 lb), SARA 312 Tier II annual inventory reporting.
• DHS CFATS: Appendix A Chemical of Interest. Screening threshold 2,000 lb solid (or equivalent solution content). Facilities exceeding threshold submit Top-Screen, may be tiered 1–4 for security plan requirements including background checks, perimeter controls, access restrictions, and response planning.
• OSHA PSM: 29 CFR 1910.119 Appendix A covers ammonium nitrate at 15,000 lb threshold — process hazard analysis, mechanical integrity, management of change, and incident investigation all mandatory above that quantity.
• ATF: 27 CFR 555 explosive-materials storage applies to non-detonable and blasting-agent forms of AN.
• OSHA PEL: no specific PEL for AN; nitrate dust covered under PNOR 15 mg/m³.

The 2013 West Fertilizer Company disaster is the governing case study for modern AN storage regulation. A building fire at the facility escalated to detonation of roughly 30 short tons of prilled AN in storage, killing 15 (12 volunteer firefighters responding to the initial fire), injuring approximately 260, and destroying an apartment complex, nursing home, and elementary school within blast radius. Post-incident CSB, EPA, OSHA, and state investigations found: no federal hazmat training for responders, no sprinkler system in the AN warehouse, combustible wooden construction in the AN storage building, no fire-service pre-plan, and no community-awareness disclosure under EPCRA that an AN facility of this scale existed. The Federal Fertilizer Security Act and state-level post-West tightening (Texas HB 942, Minnesota fertilizer security audits, etc.) now require: NFPA 400 Chapter 11 full compliance, fire-service pre-planning with building-specific access and water-supply disclosure, community right-to-know (LEPC) disclosure of inventory, CFATS Top-Screen where quantity threshold applies, and security-plan implementation for CFATS-tiered facilities. Operational bottom line: bulk AN storage is not a casual-handling commodity — it is a federally and state-regulated chemistry with prescriptive siting, construction, inventory, inspection, and training requirements. Solution-grade UAN storage is simpler than solid-prill storage but still triggers CFATS registration at relatively modest farm-scale volumes.

Storage Protocol — UAN Solution Tank Design and Regulatory Compliance

Tank selection (solution service): XLPE or HDPE vertical flat-bottom with 1.9+ SG rating, or 316L stainless for elevated-temperature blending service. No aluminum. No carbon steel in wetted service. Capacity 5,000–30,000 gallons for farm-scale; 50,000–500,000 gallons for terminal blending. Natural or black UV-stabilized polyethylene both acceptable outdoor.

Solid-product storage: not polyethylene tank service — handled in NFPA 400 Chapter 11 compliant warehouses with non-combustible construction, fire detection and suppression, pile-size limits (typically 4,000 tons maximum), aisle separation, and isolation from organic fuel sources including wooden pallets, fuel-oil storage, agricultural chemical pesticides, and organic agricultural product (grain, cotton, etc.).

Secondary containment: 110% of largest tank volume minimum; state regulation may require 125% at some jurisdictions. Lined concrete or HDPE geomembrane sump. Spill capture is particularly critical because AN solution is regulated under EPCRA and SARA — a reportable spill to surface water or soil triggers state notification requirements within hours.

Fittings and piping: Polymer or 316L stainless only. No aluminum, no brass, no bronze, no galvanized steel, no carbon steel. Bolted polyethylene flanges with EPDM gaskets for polymer tank interfaces. All buttress-thread and bottom-outlet fittings polymer-bodied with 316L internal hardware if any metallic component is wetted.

Venting: Atmospheric vent sized per API 2000 for normal fill and drain rates. No chemical-vent scrubber required at ambient temperature. Temperature monitoring is mandatory above 90°F — AN solution thermal stability degrades above 95°F and accelerates rapidly above 250°F (onset of decomposition). Cool-storage siting (shaded location, avoidance of south-facing black tank paint in warm climates) is good practice.

Heat trace (terminal blending): Required for 83% solution below 32°F ambient to prevent crystallization. Steam coils or electric resistance heat-trace with temperature limiters (never exceed 140°F bulk solution temperature). Farm-scale UAN 32% has a freeze point of +32°F and will partial-crystallize in any cold-climate unheated storage — recirculation pumps or tank-blanket heat trace is standard in USDA Zones 5 and colder.

CFATS compliance: Top-Screen submission required when on-site AN inventory (including AN content of UAN or emulsion) exceeds 2,000 lb equivalent. Site-security plan, background checks for employees with access, perimeter controls, and cyber-security measures apply to tiered facilities. Annual inventory reporting to LEPC (SARA 312 Tier II) above EHS thresholds.

Ammonium Nitrate FAQs — Field-Tested Answers

Can I store UAN 32% in the same HDPE tank I use for liquid urea?

Yes — UAN 32% is approximately 40% ammonium nitrate content by weight, and HDPE and XLPE are A-rated across both UAN and neat urea solution. Triple-rinse before changeover if switching between chemistries. The regulatory wrinkle: UAN tank storage may trigger CFATS registration at volumes above ~600 gallons (corresponding to 2,000 lb AN content threshold), whereas neat urea has no CFATS trigger.

Do I need a CFATS security plan for a 10,000-gallon UAN tank?

Almost certainly yes — 10,000 gallons of UAN 32% contains approximately 33,000 lb of AN equivalent, which is 16x the 2,000 lb CFATS screening threshold. Even a 2,500 gallon farm tank (~8,000 lb AN equivalent) is 4x the threshold. Submit a CFATS Top-Screen through the CISA Chemical Security Assessment Tool (CSAT), receive a tiering determination, and implement site-security plan compliance appropriate to tier (1–4). Most farm-scale facilities tier 3 or 4 with modest perimeter and access requirements; tier 1 and 2 apply to very large terminal and wholesale operations.

Can I put a UAN tank inside a heated barn to avoid crystallization?

Yes, but with care. NFPA 400 Chapter 11 requires isolation of AN-containing product from combustible fuel sources. If the barn stores diesel fuel, wooden pallets, straw, grain, or equipment with hydraulic oil, the AN tank must be in a separately partitioned, non-combustible-construction zone. Most farm facilities handle this with an outdoor tank pad and heat-traced or insulated tank rather than indoor barn storage. Consult your state fertilizer-inspection agency and local fire marshal for site-specific siting requirements.

What happens if my UAN tank overflows onto a wooden platform?

Clean immediately and thoroughly. Spilled UAN on wooden construction creates an AN-wood contact surface that, once dried, presents an accelerated fire hazard. The West Texas disaster investigation identified wooden construction and AN-soaked wood as contributing factors. Best practice is secondary containment with non-combustible (concrete, HDPE geomembrane, steel grating) surface and routine inspection. Spills to wood or cellulosic material require removal and disposal of the contaminated material as hazardous waste, not simple rinse-in-place remediation.

Why are there metal straps and restraints on my UAN tank when HDPE tanks for other chemistries don't have them?

Anchoring and seismic restraint is standard on any tank in a state with seismic-design requirements (California, Pacific Northwest, and parts of Utah and Colorado) and is specifically required under NFPA 400 Chapter 11 for AN-containing product regardless of state. Restraints prevent tank displacement in earthquake, flood, or high-wind event, which would spill product and create containment-breach conditions.

Can I use a former water tank for UAN storage?

Yes if the tank is HDPE or XLPE polyethylene rated 1.9+ SG and has no metallic fittings other than 316L stainless. Triple-rinse, flush, and verify no residual chlorine (swimming pool or potable-chlorine contamination is not compatible with AN solution). Label the tank with DOT placarding, SARA 312 hazard disclosure, and visible CFATS chemical-of-interest signage if the facility is CFATS-tiered. Most repurposed water tanks are adequate for the compatibility requirement but the regulatory compliance retrofit is the larger project.

How do I get emergency-service pre-plan coverage for my UAN tank?

Contact your local fire department and LEPC (Local Emergency Planning Committee) to file the SARA 302/312 hazard disclosure and coordinate a site pre-plan. The pre-plan documents tank location, quantity, access roads, water-supply connections, and product-specific response procedures (cool-water cooling, evacuation distance for thermal-runaway scenarios, etc.). Post-West Texas, state fire marshals and county emergency management offices have elevated engagement — reach out proactively and they will typically respond with site visit and pre-plan development within weeks.

Related Chemistries in the Agricultural Nitrogen Cluster

Related chemistries in the agricultural-nitrogen cluster (urea + ammonium + UAN + phosphate-nitrogen fertilizer):

• Urea Solution — Urea-water fertilizer chemistry
• UAN-28 (28% urea-ammonium-nitrate) — Blended-N liquid fertilizer
• UAN-32 (32% urea-ammonium-nitrate) — Higher-concentration UAN
• Ammonium Sulfate (AS) — Sulfur-plus-nitrogen fertilizer