UAN (Urea Ammonium Nitrate solution) is one of the most technologically advanced nitrogen fertilizers in modern agriculture. Over the past 10 years, its share of applied nitrogen fertilizers has grown from 5 to 18% in many markets. The reason — flexibility of application, the ability to combine with pesticides, and real cost savings on application. In this guide, we cover everything you need to know about UAN-28 and UAN-32.

What is UAN: Composition and Production

UAN (Urea Ammonium Nitrate solution) is a liquid nitrogen fertilizer — an aqueous solution of ammonium nitrate and urea. Unlike pure solutions of nitrate or urea alone, UAN contains three forms of nitrogen simultaneously:

  • Nitrate (NO₃⁻) — absorbed by plants immediately, without prior transformations
  • Ammonium (NH₄⁺) — absorbed gradually as nitrification occurs, retained by the soil cation exchange complex
  • Amide (NH₂) — hydrolyzed to ammonium within 3–7 days, providing prolonged nutrition

This combination of forms provides rapid initial action (nitrate nitrogen) and long-lasting feeding effect (ammonium and amide). UAN outperforms solid fertilizers in terms of even nitrogen distribution in the soil and precision dosing.

UAN-28 vs UAN-32: What is the Difference

UAN-28 Urea Ammonium Nitrate 28%
N Content28%
Density1.28 g/cm³
Crystallization−17°C
NH₄NO₃ in solution~40%
CO(NH₂)₂ in solution~30%
Recommended forCold regions
UAN-32 Urea Ammonium Nitrate 32%
N Content32%
Density1.32 g/cm³
Crystallization−10°C
NH₄NO₃ in solution~45%
CO(NH₂)₂ in solution~35%
Recommended forWarmer regions

The main practical difference is the crystallization temperature. In regions with harsh winters, UAN-28 is preferable for winter storage. In warmer climates, both grades can be stored without issue.

UAN Application Methods: Three Options

1. Soil Application (Base / Pre-sowing)
UAN without dilution is applied to soil using injector applicators or disc openers at 8–10 cm depth. Eliminates ammonia volatilization. Rate: 100–200 L/ha. Timing: autumn under plowing or spring before sowing under cultivation.
2. Foliar Spray Application
UAN diluted with water 1:3–1:5 and applied by sprayer to foliage. UAN rate: 30–50 L/ha (in diluted form 120–250 L/ha working solution). Optimal growth stages: tillering to stem elongation in cereals, 2–4 leaf pairs in beet. Apply only in morning/evening hours at air temperature below +20°C with dry leaves.
3. Tank-Mix with Pesticides
The most economical method — UAN is added to the tank mix with herbicides, fungicides or insecticides. One pass of equipment — simultaneous fertilization and crop protection. Always verify compatibility with a jar test. UAN rate in mix: 15–30 L/ha at 1:5 dilution.

UAN Application Rates by Crop

Crop Method UAN Rate, L/ha Timing
Winter Wheat Soil 100–150 Early spring, vegetation restart
Winter Wheat Foliar (1:4 dilution) 30–50 Tillering (BBCH 25–29), stem elongation (BBCH 31–37)
Maize Soil + Foliar 120–180 + 40–60 Pre-sowing + 3–5 leaf stage (BBCH 13–15)
Sunflower Soil 100–160 Pre-sowing under cultivation
Sugar Beet Foliar in herbicide tank-mix 20–40 2–3 leaf pairs (BBCH 14–16)
Winter Rapeseed Soil + Foliar 100–140 + 30–40 Spring (BBCH 30–31) + stem elongation
Spring Barley Soil 80–120 Pre-sowing application

Economics: UAN vs Ammonium Nitrate

At a nitrogen rate of 120 kg/ha, a cost comparison example:

Ammonium Nitrate: 350 kg/ha × market price + application by spreader = higher total cost per ha

UAN-32: 375 L/ha applied combined with herbicide pass = lower total cost per ha, saving one equipment pass

Combining UAN application with herbicide treatment saves one full equipment pass — typically 800–1,200 currency units per ha depending on region.

UAN Compatibility with Pesticides: Rules

One of UAN's main advantages is the ability to mix with most crop protection products. However, compatibility must be verified for each specific combination.

Jar Test (Required Before Every New Mix)

  1. Pour 250 mL of water into a clear glass jar
  2. Add UAN in the same proportion as in the tank mix
  3. Add the pesticide at the calculated rate
  4. Mix and observe for 15–20 minutes
  5. Signs of incompatibility: separation, sediment, colour change, gas formation, strong heating
Product Group Compatibility with UAN Note
Glyphosate herbicides Good UAN enhances glyphosate action on grass weeds
Sulfonylurea herbicides Good Jar test required for the specific product
Dicamba-based herbicides Caution Possible precipitation at high rates. Jar test mandatory.
Fungicides (triazoles, strobilurins) Good Common practice on cereals
Insecticides (pyrethroids) Good Generally no restrictions
Micronutrients (chelates) Good Often enhances the overall feeding effect
Important for foliar UAN application: do not treat when dew is present, at temperatures above +25°C, or in strong wind. Undiluted UAN causes chemical leaf burn. Always dilute at minimum 1:3.

UAN Storage and Transportation

UAN is a liquid with moderate corrosive activity. Storage requirements are significantly less demanding than for ammonium nitrate:

  • Tanks — stainless steel, fibreglass (FRP), high-density polyethylene (HDPE). Do not use: ordinary carbon steel without anticorrosive coating, copper, zinc, brass
  • Storage temperature — above the crystallization point (+2…+5°C in winter for UAN-28, +5…+10°C for UAN-32)
  • Fire and explosion safety — UAN is non-explosive, non-flammable, and requires no special storage class unlike ammonium nitrate
  • Transportation — stainless steel or food-grade polyethylene tanker trucks, specialised rail tank cars

If UAN crystallizes (turns cloudy) in frost — this is not a defect. After warming and mixing, the fertilizer fully regains its properties.

Equipment for UAN Application

Effective UAN use requires specialised equipment:

  • Soil application — applicator units with injector tubes or disc openers (e.g. Amazone UX series)
  • Foliar application — any boom sprayer with stainless steel or plastic nozzles and tank. Copper and bronze components are prohibited
  • Nozzles — flat fan nozzles for foliar application (110° angle), air-induction (anti-drift) nozzles in windy conditions
Looking to buy UAN-28 or UAN-32 wholesale? We supply by tanker truck from 3 t and rail tanker from 50 t. Manufacturer prices.