It will certainly give you reason to keep your doubts. It covers several manufacturers controllers and the results are spotty.
Here is the summary.
A smart controller testing facility was established by the Irrigation Technology Center at Texas
A&M University in College Station in 2008 in order to evaluate their performance from an “end-
user” point of view. The “end-user” is considered to be the landscape or irrigation professional
(such as a Licensed Irrigator in Texas) installing the controller. Controllers are tested using the
Texas Virtual Landscape which is composed of 6 different zones with varying plant materials,
soil types and depths, and precipitation rates.
This report summaries the results from the 2010 evaluations. Eight controllers were evaluated
over a 238 day period, from March 29 - November 22, 2010. Controller performance is analyzed
for the entire evaluation period as well as seasonally (spring, summer, fall). Controller
performance is evaluated by comparison to the irrigation recommendation of the TexasET
Network and Website (http://texaset.tamu.edu
). This year, we introduce a new evaluate
methodology: irrigation adequacy in order to identify controllers which apply excessive and
inadequate amounts of water.
Programing smart controllers for specific site conditions continues to be a problem. Only two (2)
of the eight (8) controllers tested could be programmed directly with all the parameters needed to
define each zone.
The 2010 results showed an increase in controller performance compared to the Year One and
Year Two results. However, we continue to see controllers irrigating excessively; some irrigated
in excess of ETc even though 17 inches of rainfall fell during the study.
Total Irrigation Amounts
• When looking at total irrigation amounts for the entire landscape, one (1)
controller was within +/- 20% the recommendation of the TexasET Network for
five (5) stations
• Two (2) controllers applied greater than a simple ETc model (ETo x Kc, neglecting
rainfall) and one (1) controller was greater than ETo.
• No controllers were consistently able (across all 6 stations) to adequately meet the
plant water requirements throughout the entire season.
• The results showed inconsistency in performance by the 8 controllers, with three
(3) controllers irrigating excessive volumes and four (4) controllers irrigating
• Two (2) controllers had five (5) stations irrigate adequate amounts and two (2)
controllers had four (4) stations irrigate adequate amounts.
Factors that could have caused over/under irrigation of landscapes are improper ETo calculations
and insufficient accounting for rainfall. Only three (3) controllers were equipped with “tipping
bucket” type rain gauges which actually measure rainfall. Two of these were consistency among
the top 3 performing controllers.
Based on 2010 performance, controllers which used onsite sensors for ET calculations irrigated
closer to the recommendations of the TexasET Network than those which operate on an ET
subscription. It was observed that controllers that used on site sensors more often produced
inadequate irrigation amounts compared to ET subscription controllers that generally produced
excessive irrigation amounts.