What Is UAN Liquid Fertilizer (Analysis & Rates)
UAN liquid fertilizer is a nitrogen solution sold in grades such as 28-0-0, 30-0-0, and 32-0-0. The first number is the percentage of nitrogen by weight; the zeros indicate no guaranteed phosphate or potash in those grades. To find gallons per acre, divide the target pounds of nitrogen per acre by the product’s pounds of nitrogen per gallon.
If you are choosing a fertilizer for a high-value crop or carefully managed lawn, the grade alone does not tell you how much to apply. You also need the product’s density, the recommended nitrogen rate, the right equipment, and the label directions. I use a simple worked calculation to explain the numbers, but it is not a crop recommendation: your soil test, local guidance, and product label must set the actual rate.
What UAN Liquid Fertilizer Is and What Its Analysis Means
UAN is a liquid nitrogen fertilizer made from urea and ammonium nitrate dissolved in water. Its grade tells you the percentage of nitrogen by product weight, not by volume. That distinction matters because a gallon weighs more than a gallon of water, and the weight varies by UAN grade.
The three common grades are 28-0-0, 30-0-0, and 32-0-0. In 28-0-0, for example, 28 means 28% nitrogen by weight. The two zeros mean the product has no guaranteed phosphate or potash in that analysis. It does not mean the fertilizer contains no water or other ingredients.
UAN nitrogen is typically present in three forms: about 50% urea-N, 25% ammonium-N, and 25% nitrate-N. These proportions can vary, so check the product label for the formulation you have. The forms differ in how they behave in soil and plants, but the grade’s total nitrogen is the figure used for the basic rate calculation.
| UAN grade | Nitrogen by weight | Approx. weight at 60°F | Approx. nitrogen per gallon |
|---|---|---|---|
| 28-0-0 | 28% | 10.65 lb/gal | 2.98 lb N/gal |
| 30-0-0 | 30% | 10.8 lb/gal | 3.24 lb N/gal |
| 32-0-0 | 32% | 11.06 lb/gal | 3.54 lb N/gal |
These weights are approximate. Use the supplier’s density for calibration, since density changes with temperature and can vary by product. The product label and supplier data take priority over a general reference value.
UAN Product Selection, Rate Calculation & Safety Preparation
UAN selection starts with the nitrogen rate that fits the crop, soil, and application timing, not with the highest grade on the shelf. Once that rate is set, density and analysis convert pounds of nitrogen into gallons of product. Treat the math as a measurement tool, not as a recommendation to apply a particular amount.
Step 1: Confirm the target rate. Use a current soil test, crop or turf recommendations, and the product label to determine the needed nitrogen rate and timing. Rates can differ by crop, soil, growth stage, and local rules. There is no universal UAN rate that suits every field or lawn.
Step 2: Find nitrogen per gallon. Multiply the product’s density in pounds per gallon by its nitrogen fraction. For UAN-28, using the approximate density above:
10.65 lb/gal × 0.28 = 2.98 lb nitrogen per gallon.
For UAN-32:
11.06 lb/gal × 0.32 = 3.54 lb nitrogen per gallon.
Step 3: Convert the target rate to product volume. Divide the target pounds of nitrogen per acre by pounds of nitrogen per gallon:
Product gallons per acre = target lb N/acre ÷ lb N/gal.
| Example target | UAN-28 calculation | UAN-32 calculation |
|---|---|---|
| 100 lb N/acre | 100 ÷ 2.98 = about 33.6 gal/acre | 100 ÷ 3.54 = about 28.2 gal/acre |
This is arithmetic only, not a universal agronomic recommendation. It assumes the approximate densities shown and does not account for field conditions or label limits. Use the supplier’s density for an exact calculation, then check the resulting nitrogen rate against the recommendation and label.
A common and costly mistake is to read “100 lb N/acre” as “100 gallons of UAN per acre.” Those are different units. At the approximate densities above, 100 gallons would deliver about 298 lb N/acre from UAN-28 or 354 lb N/acre from UAN-32. Always write down the units and check the calculated nitrogen rate before application.
Before handling UAN, read the label and safety data sheet (SDS). Wear the chemical-resistant gloves, eye protection, and protective clothing they require. Keep people, pets, and water bodies clear during handling and application, and follow label directions for setbacks and exposure.
Field Application: Calibration, Coverage & Crop Protection
Calibration means checking that the equipment applies the intended amount over a known area. It links the calculated gallons per acre to the actual flow from the tank, hoses, and nozzles. A correct calculation cannot prevent over- or under-application if the machine delivers the wrong volume.
First, inspect the tank, hoses, seals, filters, and nozzles for leaks, wear, or signs of incompatibility. Use only materials approved by the equipment maker and fertilizer supplier. Then calibrate at the intended travel speed, pressure, and swath width, following the equipment maker’s instructions.
A practical check is to measure how much product the setup delivers while covering a known area under the planned operating conditions. Compare that measured volume with the intended gallons per acre. If it differs, adjust the equipment as directed, then repeat the check. Do not assume the same settings will give the same rate after changing speed, pressure, nozzle, or swath width.
Measure product with calibrated equipment or by weight. During application, maintain even coverage and follow label-required setbacks. For foliar or turf use, follow the label’s concentration and application conditions. Concentrated UAN can scorch foliage, especially when plants are under heat or drought stress or when the product dries slowly. Avoid guessing at a dilution or applying outside label directions.
Illustrative field scenario: A recommendation calls for 100 lb N/acre, and the available product is UAN-32. The calculation gives about 28.2 gallons per acre using the approximate density in the table. Before treating the field, the operator must still confirm that the recommendation applies to that crop and timing, check the label, use the supplier’s density, and calibrate the equipment. The calculation alone does not establish that the rate is appropriate.
Equipment Cleaning, Inspection & Calibration Maintenance
Equipment condition affects both application accuracy and safe handling. A small leak can expose people or contaminate an area, while a blocked or mismatched nozzle can change delivery. Inspect the system before use, and clean it after application as the product label and equipment instructions direct.
Before each job, check the tank, hoses, connections, seals, filters, and nozzles. Look for leaks or damage, and confirm that the wetted parts are approved for the product. Calibrate again if you change the operating speed, pressure, nozzle, or swath width, or if repairs may have changed flow.
After use, rinse equipment as the label directs. Do not discharge rinse water or leftover product where it could reach a drain, water body, or other sensitive area. Manage rinsate according to the label and local rules. Record the product name and analysis, rate, treated area, date, and weather; those notes help you review what was applied and plan later work.
UAN Storage, Spill Response & Seasonal Handling
Safe storage keeps the fertilizer contained and helps preserve clear records about the product on hand. Follow the label and SDS for storage conditions, container handling, and spill response. Do not rely on a general cleanup method, because the right steps depend on the product, spill size, and location.
Keep the container secure and follow its label for storage and handling. Keep unauthorized people and pets away, and prevent product from reaching drains or water. If a spill occurs, use the label and SDS instructions and any applicable local requirements. For a large spill, or one that could reach water, follow emergency directions and contact the relevant local response authority.
At the end of the season, store remaining product only as the label permits. Keep its label available, and do not transfer it to an unmarked container. Check that equipment is clean and stored as directed by its maker, and keep application records with the product information.
Common Questions About UAN Analysis and Rates
These quick answers clarify the grade, units, and calculation steps. They do not replace the product label, local rules, or crop-specific recommendations. When a label or supplier specification differs from a general estimate, use the product-specific information.
What does 28-0-0 mean?
It means the fertilizer is 28% nitrogen by weight, with no guaranteed phosphate or potash in that grade.
How much nitrogen is in a gallon of UAN-28?
About 2.98 lb of nitrogen per gallon using an approximate density of 10.65 lb/gal at 60°F. Use the supplier’s density for a more exact value.
How much nitrogen is in a gallon of UAN-32?
About 3.54 lb per gallon using an approximate density of 11.06 lb/gal at 60°F. Actual density can change with temperature and product.
How many gallons of UAN-32 provide 100 lb N/acre?
About 28.2 gallons per acre using the approximate values in this guide. This is a calculation example, not a recommendation to apply 100 lb N/acre.
Is UAN-32 always better than UAN-28?
No. A higher grade supplies more nitrogen per gallon, but the best choice depends on the recommendation, equipment, product availability, and label directions.
Can I apply UAN to leaves or turf?
Only when the product label permits that use and gives directions for concentration and conditions. Concentrated UAN may scorch foliage, especially during heat, drought stress, or slow drying.
Why does temperature matter to the calculation?
UAN density changes with temperature. Since the calculation uses pounds of product per gallon, use supplier density for the conditions and product being handled.
What is the main rate-calculation error to avoid?
Do not treat pounds of nitrogen per acre as gallons of fertilizer per acre. Convert using the product’s nitrogen per gallon, then check the result against the crop recommendation and label.
What should I check before applying UAN?
Confirm the recommended nitrogen rate and timing, read the label and SDS, inspect compatible equipment, calibrate at the planned settings, and use required protective gear.
What should I do with rinsate or a spill?
Follow the product label, SDS, and local requirements. Prevent rinsate or spilled product from reaching drains or water, and do not use an improvised cleanup or disposal method.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
