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item Colvin, Thomas

Submitted to: Integrated Crop Management Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/4/2003
Publication Date: 12/4/2003
Citation: Hanna, M.H., Baumgartner, K.J., Colvin, T.S., Baker, J.L. 2003. Application uniformity of an impellicone anhydrous ammonia manifold. Integrated Crop Management Conference Proceedings. Ames, IA: Iowa State University Extension. p. 155-164.

Interpretive Summary:

Technical Abstract: Since the 1960's, anhydrous ammonia (NH3) has become the most widely used source of nitrogen (N) fertilizer in agriculture. In fact over 8.1 billion pounds of NH3 is used in the United States every year. With the cost and wide spread use of NH3, operators are seeking ways to improve uniformity and reduce rates of application. This is because most NH3 tends to be over-applied due to variability in NH3 equipment. Reducing variability will put more money into producers' pockets and reduce the likelihood of N leaching into water supplies. At a cost of $267/ton of NH3, improved application equipment that reduced use in the United States by 5% would result in direct savings of $65 million annually for crop producers. A key component of NH3 application equipment that affects uniformity is the distribution manifold. Tests have shown that some outlets on manifolds release two to four times as much NH3 as other outlets. Some knives could be putting on two to four times the desired rate while other knives could be putting on very little NH3. This means that some plants may be getting more N than they can use and others are not getting enough N due to poor distribution by application equipment. In recent years, new manifolds have been tested and produced that improve uniformity among distribution ports. One such manifold is the Vertical-Dam (Continental NH3 Products, Dallas, TX) which uses specific rings for certain applications and application rates. Vertical-Dam manifolds with 11 active outlets have produced coefficients of variation of 15% to 18% compared to conventional manifolds producing 30% or higher coefficients of variation. However, the Vertical-Dam does have some drawbacks. Different rings and housings may be required for different types of applications. The Vertical-Dam manifolds tend to cost three to four times more than a conventional manifold. Other prototype manifolds have been developed at Iowa State University using a cone design (impellicone) to evenly distribute NH3.