Agricultural buyers are some of our most loyal customers. Liquid fertilizer — UAN solutions (urea-ammonium nitrate), starter blends, micronutrient packages — moves through tens of thousands of totes every spring in the Midwest. The chemistry is generally tote-friendly, but a few details matter.
UAN-32 chemistry
UAN-32 is roughly 32% nitrogen by weight, a balanced mix of urea, ammonium nitrate, and water. The pH is slightly acidic to neutral (5.8–7.0 typically) and the salt content makes it electrolyte-rich. HDPE handles UAN-32 well. The cage is the more vulnerable part — galvanized steel in contact with UAN drip will corrode at the white-rust stage rapidly.
The practical implication is that cages on UAN-service totes look used. Even with no leaks, the splash and condensation around the bottom valve area accelerates galvanic loss. Inbound UAN totes from a season’s ag service typically have measurably more cage corrosion than non-fertilizer service.
Ammonia odor
UAN totes off-gas trace ammonia continuously as urea slowly hydrolyzes. The odor is faint but persistent and survives a single rinse. If a tote will go into food service after fertilizer service (we don’t do this, but it’s worth knowing why), the ammonia ghost is detectable in lab analysis for many wash cycles.
For continued fertilizer service, the ammonia ghost is irrelevant. The tote can be flushed and refilled with no consequence.
Cold-weather behavior
UAN-32 has a salt-out temperature around 32°F — the ammonium nitrate component crystallizes below that, leading to a slushy two-phase mix in the bottom of the tote. The slush is not damaging to the tote but is impossible to dispense through a 2″ valve. For winter storage, either heat the tote to 40°F+ or accept that you need a remelt cycle before spring use.
UAN-28 has a lower salt-out temperature (~5°F) and is more winter-tolerant. Most northern operations use 28 instead of 32 for stored inventory.
Bulk valve choice
Standard EPDM gaskets are fine for UAN service. We see longer gasket life on UAN service than on plain-water service, oddly — probably because the salt-rich environment inhibits some forms of biological gasket attack. Galvanized hardware (bolts, valve handles) shows accelerated corrosion. Spec stainless or coated hardware for UAN-dedicated totes if you can.
Tote tagging
UAN-service totes should be permanently tagged as “ag use, ammonia history” before going into any other service. We track this internally and decline to upcycle UAN-history bottles into food, brewing, or potable-water applications, regardless of wash status. The market for ag-to-ag turnover is robust enough that the bottles continue in service for many cycles.
Spill containment
Most state regs require secondary containment for liquid fertilizer storage above some threshold (varies by state — Ohio is 1,500 gallons aggregate, Michigan is similar). A single 330-gallon tote is below threshold but a small ag operation with five totes is over it. Plan for secondary containment from day one if you’re stacking inventory.
Questions on this one? Email info@ibctankscleveland.com. We answer everything inside one business day — usually inside four hours.