Such extreme physical properties make NH3 a challenging product for producers to handle and apply accurately and evenly, or in precision farming environments. The 44 applicators without electronic controllers had an average variation of plus or minus 16 percent of the intended application rate. The NH3 applicators with electronic controllers did a little better job. Their average variation ranged plus or minus 7.4 percent. A 1997 cooperative study conducted by Iowa State University, Successful Farming and Continental NH3 Products, found that even greater variation was possible among knives on the same applicator.
Most manifolds are simply hollow chambers with outlet holes on the perimeter.
NH3 immediately begins to vaporize into a gas as it moves out of the tank, through the hoses and into the manifold. The vapor interrupts the flow of liquid nitrogen to the hoses and knives, which disrupts uniform distribution. Often two, three or, sometimes, even four times more NH3 goes to one knife compared to another.