Monday, April 1, 2013

Nozzle up: a D.U. study!

One of the projects I’ve been working on regularly since late 2012 involves testing the distribution uniformity of several spray head nozzles at a research field on campus.

The distribution uniformity (DU) of an irrigation zone is how uniformly it applies water. The DU test is an integral part of any irrigation system audit.

A catch can grid in a research plot
Volume information obtained from the catch cans used in testing not only reveal how balanced the zone application is, but can also be used to calculate zone application rate, or how fast water is applied.

The set-up
Last year a major irrigation brand asked our group in Gainesville to begin tests on several of its spray head nozzles and a popular nozzle from a competitor.

You put a rotor where?: The UCU's Jesus Lomeli in assessment mode
In my countless irrigation system assessments with the U.C.U. in Miami-Dade County, I have seen almost every kind of nozzle in all states of disrepair/misuse. Suffice to say I was excited to work with these big name products in a controlled setting.

Before the testing could begin, twelve plots in the research field were selected (three reps per nozzle).

The research field in Gainesville: 72 plots!
The water meters on those plots were calibrated to confirm how efficient the meters tracked volumes actually applied in the field.

Large containers capture water during a specific run time

Tubing directs water from head stem into containers

Large containers are weighed to determine volume
Then the grid pattern for catch cans in the plot was determined and marked with paint.

Researcher Bernard Cardenas surveys the can pattern

Technician Sara Wynn marks can positions in the plot
Then nozzles were then attached and spray heads were oriented.

Lower Quarter D.U.
Although the DU data from these tests is analyzed in sundry ways, the foundation for all data is the Lower Quarter DU test.

The percentage the above equation generates classifies the irrigation zone's distribution uniformity as excellent, good, or poor.

All can everything!
We have been conducting DU tests consistently since early December. Recently, we experimented with a grid pattern that left no piece of the plot uncover and allowed for mocking different grid patterns in the data analysis.

Just what it looks like: 320 cans!

...and time flies during data collection!
And lately, we have been focusing primarily on conducting tests during high wind days.

Results will be made public in 2014. Stay tuned!


  1. Interesting piece about a similar study and the pros & cons of low precipitation rate nozzles.

  2. And finally, a catchy video about some DU study results generated by the University of Arizona.