Ammonium Nitrate vs Urea: Results
In this example, ammonium nitrate costs less at $550 per ton than urea at $630 per ton.
However, the cost of nitrogen per lb for urea ($0.67) is actually less than the cost of nitrogen per lb for ammonium nitrate ($0.79). This is because urea has more nitrogen than ammonium nitrate relative to the overall mass.
While urea fertilizer is slightly less expensive per unit of nitrogen, it is not immediately available like the ammonium nitrate and must first be converted or "mineralized" from the organic form to the inorganic form needed by plants.