How to calculate cost per pound of nitrogen

The formula

Nitrogen content of common sources

The percent N comes from each product’s grade. Pounds of N per ton is just 2,000 × that percentage. These are standard label analyses: Michigan State University Extension reports the same figures, including anhydrous ammonia at 82% N and ammonium sulfate at 21% N with 24% sulfur (see Sources below).

Liquids priced by the gallon

UAN is sometimes priced per gallon rather than per ton. To use the formula you need the product’s weight per gallon (ask your supplier or read the label). University of Minnesota Extension reports that a gallon of 28% UAN weighs about 10.7 lb and carries about 3 lb of N, and a gallon of 32% UAN about 3.5 lb of N. Confirm the exact weight for the product you buy.

Worked comparison

Illustrative delivered prices — not quoted prices — turned into cost per pound of N:

Cost per pound of N is not the whole story

These sources are not interchangeable. Ammonium sulfate looks expensive per pound of N here, but it also supplies sulfur, so its nitrogen cost overstates its total value where sulfur is needed. Sources also differ in handling and in how much nitrogen can be lost to the air if surface-applied without incorporation. See urea vs UAN for those differences. Which source fits your field is an agronomic decision, not a price decision.