In appropriate field conditions ammonium nitrogen can be biologically oxidized into nitrate nitrogen, which is can be easily leached from the soil profile. Georgia Pacific Inc., has developed a slow release nitrogen fertilizer to increase nitrogen availability by reducing potential nitrogen loss from the crop root zone by leaching. A field study was performed to evaluate comparative nitrogen availability of the Georgia Pacific urea formaldehyde (32% N) compound and urea ammonium nitrate (28% N) at three locations in Iowa in 2004 and two locations in 2005. 0, 50, 100, 150, 200 lbs N acre-1 of both the urea formaldehyde and urea ammonium nitrate were applied with four repetitions at each location. Availability of the fertilizer was estimated by comparing crop yield. Soil and plant samples were collected and analyzed for supplemental information regarding nitrogen levels. The yield values showed a response to rate of nitrogen fertilization at two locations, but no response was seen for the different fertilizer materials.