Anhydrous Ammonia Distribution during Field Application

Hanna, H. Mark
Hanna, H. Mark
White, Michael
Colvin, Thomas
Baker, James
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Agricultural and Biosystems Engineering

Poor knife–to–knife distribution observed in stationary tests is a concern because it may reduce efficiency of use and even lead to intentional over application of nitrogen (N) applied as anhydrous ammonia. To determine the magnitude of this problem we measured ammonia distribution by conventional, Vertical–Dam, and Cold–flo manifolds and flow division by a pipe tee during field applicator operation with ammonia flows from each port caught in water. Due to limitations of the manifolds and regulator, flow variability due to knife style and condition was determined in a stationary test using water instead of ammonia.

Port–to–port variability was less for a Vertical–Dam manifold than a conventional manifold at a 56–kg N/ha (50–lb N/acre) application rate, but similar for both manifolds at application rates of 112 and 168 kg N/ha (100 and 150 lb N/acre). The Cold–flo manifold also had similar variability to the other two manifolds at the 112–kg N/ha (100–lb N/acre) rate. Ammonia exiting individual outlet ports was typically 10 to 20% from the mean application rate with highest port flow 150 to 250% of lowest port flow.

Statistically, manifolds had the greatest ammonia output from ports across from incoming flow, intermediate output from ports behind incoming flow, and least output from ports on either side of the manifold midway between these regions. A straight entry pipe did not improve distribution for a conventional manifold. A pipe–tee divided flow evenly, with only an average 2.4% flow difference. Different knife styles had different flow rates suggesting knives, particularly new ones, should be carefully inspected and matched on the applicator.


This article is from Applied Engineering in Agriculture 18 (2002): 443–451, doi:10.13031/2013.8747.