west Nebraska northeast Colorado | 32% or 28% UAN fertilizer is simply a mixture of Urea, Ammonium Nitrate, and water. The more water you add, the lower the concentration of nitrogen in the solution. The reason you don't see mixtures "stronger" than 32% nitrogen is because the nitrogen will start to "salt out" (come out of solution and form a solid substance on the bottom of the tank) at fairly high temperatures. (a 34% UAN solution will salt out at appx. 50 degrees F). You can add water to lower the freezing point, but only to a certain point. For example, 2% UAN freezes at 27 degrees F, 14% UAN freezes at 0 degrees F, and 24% UAN Freezes at somewhere around -15 degrees F. Much more UAN than that however, and the problem becomes salt out. 28% UAN salts out (forms a solid precipitate) at appx. 0 degrees F, 32% UAN salts out at appx. 32 degrees F.
See the University of Nebraska Publication Crowbar referenced above, or google "Fluid Fertilizers:Properties and Characteristics + Leikam (see the chart on page 16 of Leikam) for a graph of this. The line on the left going down is freeze point, the line on the right going back up is salt out)
To the O.P. how cold do you want to protect to? I believe if you mix 14.5 gal of 32% UAN solution with 100 gal of additional water you will have a 5.1% UAN solution than won't freeze until 21 degrees F or so. I have not done this, but believe the calculations are correct. |
32% for anti freeze on tanker
