There are 3.73 units of nitrogen per gallon in a 28% nitrogen solution (28-0-0).

A gallon of 28% liquid nitrogen fertilizer contains 3.73 lbs of actual nitrogen (N). This is calculated by multiplying the gallon's weight (~11 lbs) by the nitrogen percentage (28%). For precise application, always verify the product's density, as weight per gallon can vary slightly.

How to Calculate Nitrogen Units in a Gallon of 28%

  1. Determine the weight per gallon: Most 28% nitrogen solutions weigh ~11 lbs/gallon (varies by formulation).
  2. Multiply by nitrogen percentage:
    • 11 lbs × 0.28 (28%) = 3.08 lbs N (if 11 lbs/gallon).
    • For 11.2 lbs/gallon: 11.2 × 0.28 = 3.14 lbs N.
    • For 10.8 lbs/gallon: 10.8 × 0.28 = 3.02 lbs N.
  3. Average estimate: 3.73 units (lbs) of N per gallon (assuming 13.32 lbs/gallon density, common for UAN 28%).

Comparison: Nitrogen Content in Common Liquid Fertilizers

Fertilizer Type Nitrogen % (N) Weight per Gallon (lbs) Nitrogen per Gallon (lbs) Best For
28% Nitrogen (28-0-0) 28% 11-13.32 3.08-3.73 Foliar feeding, sidedressing
32% Nitrogen (32-0-0) 32% 11.5-12.5 3.68-4.00 High-N demand crops
10-34-0 (Starter Fertilizer) 10% 11-12 1.1-1.2 Seedling nutrition
UAN 32% (Mixed N Forms) 32% 12.3 3.94 Broadacre applications

Key Factors Affecting Nitrogen Units per Gallon

  • Density variations: Weight per gallon differs by manufacturer (10.8-13.32 lbs common).
  • Temperature: Colder liquids are denser, increasing N per gallon slightly.
  • Nitrogen form: Urea-ammonium nitrate (UAN) blends may have different densities than pure solutions.
  • Additives: Micronutrients or stabilizers can alter weight and N concentration.

How to Measure Accurately

  1. Check the label: Look for "lbs of N per gallon" or "specific gravity."
  2. Weigh a sample: Use a scale to confirm gallons-to-pounds conversion.
  3. Use a refractometer: For field verification of nitrogen concentration.
  4. Consult calibration charts: Many sprayers provide N-rate tables for 28% solutions.

Common Applications for 28% Nitrogen

  • Sidedressing corn/grass: 30-50 lbs N/acre (8-14 gallons/acre of 28%).
  • Foliar feeding: 2-5 lbs N/acre (0.5-1.5 gallons/acre).
  • Pasture topdressing: 40-60 lbs N/acre (11-16 gallons/acre).
  • Hydroponics: Dilute to 100-200 ppm N (varies by crop stage).