Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering

First Advisor

James L. Baker


Experiments conducted between August 1999 and April 2002 evaluated anhydrous ammonia (NH3) manifold distribution during field application at 84 kg N/ha and 168 kg N/ha application rates. Conventional, Vertical-Dam, Rotaflow(TM), Equa-flow(TM), FD-1200 prototype, and a new prototype manifold named the Impellicone were evaluated. At the 84 kg N/ha rate, all manifolds tested had significantly lower application variation than the conventional manifold. At the 168 kg N/ha rate the conventional, Vertical-Dam with a corn ring, and the FD-1200 prototype had significantly higher application variation than the other manifolds tested.;Analysis of temperature and pressure data indicated that NH3 flowing through the system very closely follows the saturation line. Predictions of NH3 quality assuming saturated conditions would be would be acceptable. Investigation for correlation between coefficient of variation (CV) and air temperature or percent of volume in the vapor phase of NH 3 resulted in only a significant correlation between CV and percent of volume in the vapor phase of NH3 for the conventional manifold.;Conclusions suggest that replacement of a conventional manifold with a Vertical-Dam manifold or any of the other manifolds tested could reduce application variation, and as a result reduce application rate by eliminating the need for overapplication to compensate for variations.;Anhydrous ammonia was applied between corn rows in varying amounts to measure corn yield response. Results showed that for one of the three years measured, large variations in application rate lowered the plot yield. No plot yield reduction was measured for the other two years. Comparisons showed a significant correlation between stalk-N concentration (ppm NO3-N) and application rate. Stalk-N concentration and nitrogen content of the grain did a poor job of predicting yield.



Digital Repository @ Iowa State University,

Copyright Owner

Paul McAteer Boyd



Proquest ID


File Format


File Size

159 pages