Comparison of Exactrix and Conventional Fertilizer Application In Corn.

The cost of nitrogen fertilizer has increased dramatically over the past ten years and remains very volatile. Corn producers in the Southern High Plains are aware of this and are exploring options for different methods of nitrogen application. The Exactrix system dually applies NH₃ with ammonium polyphosphate (APP) (ie. 10-34-0), and ammonium thiosulfate (ATS) (ie. 12-0-0-26S), through two tubes mounted on injection knives. These two fertilizers then collide creating a crystalline form called triammonium polyphosphate sulfate.  In 2008, a two year study was initiated to compare the yield response of corn to nitrogen applied with the Exactrix system to a conventional liquid method of application.  A split plot design was used, with the main effect being the method of application, and nitrogen rate as a subplot.  Four replications of 0, 89.6, 179.2 and 268.8 kg ha^-1 nitrogen were applied over 1114 m² plots.  The Exactrix application method did not increase corn yield over conventional fertilizer application at any of the N rates tested in this study. Further, there was no indication that N use efficiency was improved with the Exactrix system, such that fertilizer N rates could be reduced when compared to conventional application methods and products. Four-foot samples collected before planting and after harvest suggest that N was used as deep as 4-ft in the profile.