WaterSense Notice of Intent (NOI) to Develop a Draft Specification for Soil Moisture-Based Control Technologies

WaterSense

WaterSense Notice of Intent

WaterSense® Notice of Intent (NOI) to Develop a Draft
Specification for Soil Moisture-Based Control

Technologies

I. Introduction

Residential outdoor water use in the United States accounts for nearly 9 billion gallons of
water each day,1 mainly for landscape irrigation. As much as half of this water is wasted
due to evaporation, wind, or runoff, often caused by improper irrigation system design,
installation, maintenance or scheduling. In addition to working with irrigation
professionals to increase water efficiency outdoors, the U.S. Environmental Protection
Agency's (EPA's) WaterSense program is addressing irrigation scheduling by labeling
efficient irrigation system control technologies. EPA released the final WaterSense
Specification for Weather-Based Irrigation Controllers in 2011. With the release of this
NOI, EPA is indicating its intent to issue a draft specification for soil moisture-based
control technologies.

By directly measuring the amount of moisture in the soil, soil moisture-based control
technologies tailor irrigation schedules to meet landscape water needs based on
seasonal patterns, as well as prevailing conditions in the landscape. Allowing soil
moisture-based control technologies to earn the WaterSense label will help further
transform the market from traditional clock timer-based irrigation control to control
technologies that schedule irrigation based on landscape water needs.

II. Background

The most common technology used to schedule irrigation is a manually programmed
clock timer that irrigates for a specified amount of time on a preset schedule
programmed by the user (e.g., 20 minutes, three days per week). In these systems, the
responsibility of changing the irrigation schedule to meet landscape water needs lies
with the end user or a hired irrigation professional. Clock timer controllers can be a
significant source of wasted water because irrigation schedules are often set to water at
the height of the growing season, and the home or building owner may not adjust the
schedule to reflect seasonal changes or changes in plant watering needs. For example,
plant water requirements decrease in the fall, but many home or building owners neglect
to reset their irrigation schedules to reflect this change (see Figure 1). Therefore, an
irrigation system may be watering in January as if it were July.

1 Kenney, Joan F., et al. "Estimated Use ofWater in the United States in 2005." U.S. Geological Survey
Circular, 1344. Department of the Interior. Table 6, page 20.

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Typical Irrigation Levels and Plant Water Needs

E
<

Potential water
savings

Average level
at which many
home owners
irrigate

Plant water
requirements

Mar

Jul

Nov Mar Jul
Seasonal Fluctuation

Nov

Mar

Figure 1. Potential Water Savings from Adjusting Irrigation Scheduling Based on

Landscape Water Needs

As an alternative to clock timer controllers, soil moisture-based control technologies
make irrigation schedule adjustments by automatically tailoring the amount and/or
frequency and timing of irrigation events based on the moisture content of the soil in the
landscape. There are currently two types of soil moisture-based control technologies:
bypass (i.e., watering interruption) technologies and on-demand technologies.

• Bypass technologies include a soil moisture sensor that communicates with a
device that is attached to a traditional clock timer controller with a pre-
programmed watering schedule. The attached device will inhibit or suspend an
irrigation event based on a reading from the soil moisture sensor, if the soil
moisture meets a set moisture threshold. Otherwise, it will allow the irrigation
event to occur. Bypass technologies are usually installed on residential and light
commercial landscapes and are the most commonly used type of soil moisture-
based control technology.

• On-demand technologies are stand-alone controllers that communicate with
associated soil moisture sensors. These controllers automatically adjust irrigation
schedules based on soil moisture levels. For example, in some technologies, a
lower and upper soil moisture threshold is set in the controller. When the soil
moisture sensor reads moisture content below the lower threshold, the controller
will initiate irrigation until the upper threshold is reached. On-demand
technologies are typically installed on larger commercial landscapes and are not
as common as bypass technologies.

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Research studies suggest that bypass technologies can achieve water savings of more
than 20 percent over systems scheduled with clock timer controllers. Appendix A lists
the water savings studies that WaterSense has identified to date. Note that the listed
studies identified by WaterSense pertain to bypass technologies only. WaterSense has
not identified any studies that examine water savings of on-demand technologies.

While there are currently no federal standards for soil moisture-based control
technologies, the American Society of Agricultural and Biological Engineers (ASABE) is
developing two standards for these products: S633, Testing of Soil Moisture Sensors for
Landscape Irrigation, and S627, Standardized Testing Protocol for Weather-based or
Soil Moisture-based Landscape Irrigation Control Devices. The ASABE S633 Committee
is working to include in the standard a test protocol for bypass technologies that will
determine the responsiveness of soil moisture sensors and their associated interrupt
devices. ASABE S627 focuses on the test protocols for weather-based irrigation
controllers and on-demand soil moisture-based technologies. The ASABE S627
Committee is basing its standard on the Smart Water Application Technologies (SWAT)
8th Testing Protocol for Climatologically Based Controllers and the SWAT Operational
Test for Soil Moisture Sensor-Based Controllers, Version 3.0.

WaterSense intends to ultimately develop specifications for both bypass and on-demand
technologies. Separate specifications for these technologies are required because they
function differently from one another and will need to be tested according to their
function. WaterSense is focusing its initial specification development efforts on bypass
technology because the fundamental aspects of the performance test protocol for that
technology have been fully defined by the S633 Committee mentioned above.
WaterSense plans to address on-demand technology at a later date. WaterSense
intends to continue working with the ASABE S627 Committee and will have a clearer
picture of the timeframe associated with the specification development process for on-
demand technologies once the committee more fully defines the fundamental aspects of
that test protocol. The remainder of this NOI focuses on EPA's plans for developing a
draft WaterSense specification for bypass soil moisture-based control technologies.

III.	Scope

WaterSense intends that the specification will apply to bypass soil moisture-based
control technologies used in residential and commercial landscape applications. The
product being tested and labeled will include the soil moisture sensor itself and the
device that interrupts the signal from the controller to irrigate.

IV.	Performance Measures

WaterSense intends to work through the ASABE S633 Committee to develop a
performance test protocol and performance measures that assure the performance of
bypass type soil moisture-based control technologies with respect to their intended
purpose. The performance test protocol should test the ability of the product to sense
soil moisture accurately and reliably bypass irrigation events at preset soil moisture
values.

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Once a performance test protocol is available, WaterSense will need to examine actual
performance data resulting from the protocol on a range of products prior to developing
a draft specification for this technology. This will require that a number of products
available on the market undergo round robin testing with a number of independent
laboratories to ensure that the performance test protocol is repeatable. The data
generated from the round robin testing will be used to assess the range of performance
that is achievable for the products on the market. These data will inform an appropriate
threshold for product performance. The threshold will consider both the top echelon of
products on the market and the minimum performance level that is necessary to ensure
these products can accurately sense the moisture content of the soil and serve their
intended function.

To aid in assuring the performance test protocol is repeatable and produces a body of
data from round robin testing, WaterSense has developed a draft research proposal to
seek support to accomplish the following objectives:

1.	To evaluate and ensure that the performance test protocol for bypass type soil
moisture-based technology included in ASABE S633, Testing of Soil Moisture
Sensors for Landscape Irrigation, is repeatable among independent laboratories.

2.	To provide performance data that could inform the establishment of performance
level thresholds for bypass type soil moisture-based technologies.

Additional information on the research proposal is located in Appendix B.

V. Outstanding Questions and Issues

WaterSense welcomes feedback on all aspects of this NOI, but is seeking specific input
on the following outstanding questions and issues:

1.	Are the definitions of bypass and on-demand technologies clear and
appropriate?

2.	Regarding performance, WaterSense intends to test the accuracy of the soil
moisture sensor in assessing the moisture content of soil and the device's
ability to bypass an irrigation event based on preset soil moisture content.

i.	Are these appropriate performance attributes?

ii.	Are there additional performance attributes that WaterSense
should consider in developing a draft specification for bypass soil
moisture-based control technologies? Please provide associated
test protocols, if applicable and available.

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3. WaterSense has identified a number of studies that examine the water
savings of soil moisture-based control technologies. Please submit any
additional studies or data you would be willing to share on product
performance and/or water use that are not included in Appendix A.

VI. Schedule and Next Steps

As mentioned above, WaterSense plans to work through the ASABE S633 Committee to
develop a performance test protocol that is suitable for use in a WaterSense
specification for bypass type soil moisture-based control technologies. The timeline for
the development of a draft specification is largely dependent on the progress made by
the ASABE S633 Committee and the resolution of the outstanding questions and issues
described above.

All interested parties are encouraged to submit written information and comments
regarding any of the concepts or issues presented in this NOI to EPA's contractor at
watersense-products@erq.com. All feedback will be taken into consideration as
WaterSense prepares to develop a draft specification for bypass soil moisture-based
control technologies.

VII. References

Allen, Richard G. 1997. U.S. Bureau of Reclamation Provo Area Office. Project
Completion Report: Demonstration of Potential for Residential Water Savings Using a
Soil Moisture Controlled Irrigation Monitor.

Augustin, B.J. and G.H. Snyder. 1984. "Moisture Sensor-Controlled Irrigation for
Maintaining Bermudagrass Turf." Agronomy Journal. Vol. 76. Pages 848-850.

Blonquist Jr., J.M., et al. April 4, 2006. "Precise irrigation scheduling for turfgrass using a
subsurface electromagnetic soil moisture sensor." Agricultural Water Management.

Cardenas-Lailhacar, B., et al. 2008. "Sensor-Based Automation of Irrigation on
Bermudagrass during Wet Weather Conditions." Journal of Irrigation and Drainage
Engineering. Vol. 134(2). Pages 120-128.

Cardenas-Lailhacar, B., et al. 2010. "Sensor-Based Automation of Irrigation on
Bermudagrass during Dry Weather Conditions." Journal of Irrigation and Drainage
Engineering. Vol. 136(3). Pages 184-193.

Davis, Stacia L. and Michael D. Dukes. 2012. University of Florida Agricultural and
Biological Engineering Department. Implementation of Smart Controllers in Orange
County, FL: Results from Year One.

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DeOreo, W.B. and P. Lander. 1994. Automated Irrigation Scheduling Using Soil Moisture
Sensors. ASAE Paper No. 94-2119.

DeOreo, W.B. 1997. Evaluation of Reliability and Cost Effectiveness of Soil Moisture
Sensors in Extended Field Use. City of Boulder, Office of Water Conservation. Boulder,
Colorado.

Haley, Melissa B., and Michael D. Dukes. 2012. "Validation of Landscape Irrigation
Reduction with Soil Moisture Sensor Irrigation Controllers." Journal of Irrigation and
Drainage Engineering. Vol. 137(2). Pages 135-144.

Irrigation Association of Australia. Summer 2004. "Irrigation Technology - Urban: Soil
Moisture Sensor Helps Save Water." Irrigation Australia. Vol. 19(4). Pages 13-15.

McCready, M.S., et al. 2009. "Water conservation potential of smart irrigation controllers
on St. Augustine grass." Agriculture Water Management. Vol. 96(11). Pages 1623-1632.

Pathan, S., et al. 2003. "Soil Moisture Sensor Controlled Irrigation for Maintaining Turf."
Irrigation Australia. Vol. 18(4). Pages 7-11.

Quanrud, David and Glenn France. 2007. Arizona Department of Water Resources.
"Smart" Irrigation Controller Study in Tucson, Arizona.

Shedd, Mary, et al. May 2007. University of Florida Agricultural and Biological
Engineering Department. Evaluation of Evapotranspiration and Soil Moisture-based
Irrigation Control on Turfgrass.

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APPENDIX A: Soil Moisture Sensor Water Savings Studies

Study
Reference

Study
Location
and/or
Sponsor

Product(s)
Tested

Objective(s) of Study

Study Findings(s)
Relevant to Soil Moisture
Sensors

Residential Field Studies

DeOreo,
1997

City of
Boulder,
Office of
Water

Conservation

(Boulder,

Colorado)

Watermark
(Irrometer
Company Inc.)

(1)	To understand the
time and expense
required to maintain
the soil moisture
sensor irrigation
systems.

(2)	To understand how
systems performed
in the field after
several years.

(3)	To understand how
well irrigation
applications matched
theoretical ET
requirements.

¦	Irrigation occurred at 76
percent of the theoretical
evapotranspiration (ET)
value.

¦	Systems were reliable
following 3-5 years in the
field.

¦	Maintenance
requirements were ~6-
7min/week/unit

¦	Some fine tuning was
required.

¦	Irrigation scheduling
tables were developed to
monitor performance.

Allen, 1997

U.S. Bureau
of

Reclamation
Utah Office
and Utah
State
University
(Salt Lake
City and
Providence,
Utah)

Water Watcher
System (Turf
Tech, Inc.)3

To demonstrate soil
water control
technology for
conserving irrigation
water use by
residential users.

¦ On average, the 27
participants

demonstrated 10 percent
reduction in water use
compared to 39 control
households.

Irrigation of

Australia,

2004

Defence

Housing

Authority and

Water

Corporation

(Perth,

Australia)

Watermatic soil
moisture sensor
(Watermatic
Irrigation
Company)3

To evaluate potential
water savings using
different types of
irrigation control
devices.

¦ Total water savings of 41
percent were
demonstrated in
households using soil
moisture sensor
controlled irrigation
systems compared to
households using
standard irrigation
systems.

Quanrud
and France,
2007

Office of Arid
Lands
Studies at
University of
Arizona &
Arizona
Department
of Water
Resources
(Tucson, AZ)

WeatherTRAK ET

Controller

(Hydropoint)b,

WeatherMiser

temperature/humi

dity sensor

(Weathermiser)b,

and RainBird®

MS-100

(RainBird)3

To evaluate the
efficiency of several
types of smart
irrigation devices for
residential use.

¦ Results have shown that
compared to the previous
two years, there were 4.3
percent water savings
using soil moisture
sensors, 3.2 percent
using humidity sensors,
and 25 percent using ET
controllers.

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Study
Reference

Study
Location
and/or
Sponsor

Product(s)
Tested

Objective(s) of Study

Study Findings(s)
Relevant to Soil Moisture
Sensors

Haley and
Dukes, 2012

University of
Florida
(Gainesville,
Florida)

Acclima Digital
TDT RS-500
(Acclima Inc.)

To determine if
documented
irrigation reductions
found for soil
moisture sensor
under research
conditions could be
validated in actual
landscapes.

¦	Reduced irrigation
applications by 65
percent relative to homes
running on a timer-based
system.

¦	Bypassed at least 62
percent of scheduled
irrigation events that
were determined
unnecessary through soil
moisture readings.

Davis and
Dukes, 2012

University of

Florida

(Orange

County,

Florida)

Baseline
WatertecS100
(Baseline Inc.)

RainBird ESP-
SMT (RainBird)b

(1)	To evaluate types of
smart controllers to
determine whether
they can reduce
irrigation
applications.

(2)	To determine the
impact of user
training of the smart
technologies.

¦	Irrigation applications
with a soil moisture
sensor were reduced 23
percent; when a soil
moisture sensor was
combined with user
education, savings
increased to 45 percent.

¦	ET controllers reduced
irrigation applications 16
percent without user
education and 38 percent
with user education.

Turf Plot Field Studies

Augustin
and Snyder,
1984

Tennessee
Valley

Authority and

International

Minerals

Corporation

(Florida)

Irrometer TGA

Tensiometers

(Irrometer)

(1)To	investigate basing
irrigation on soil
moisture versus
clock scheduling
during periods of
high and low rainfall.

(2)	To assess the
influence of irrigation
practices on nitrogen
fertilization.

¦	Irrigation occurred 42
percent to 95 percent
less often in plots using
soil moisture sensor
controlled irrigation
compared to plots using
standard clock driven
irrigation.

¦	Plots with sensors
received 26 percent less
water than the control
plots.

¦	Better turf appearance
was noted in plots using
sensors.

Pathan et
al., 2003

University of

Western

Australia

(Perth,

Australia)

Water Smart1™
soil moisture
sensor (Rainbird)3

(1) To evaluate water
used and turf quality
of plots irrigated
using a control
system linked to a
soil moisture sensor
compared to current
best practices
recommended by
Water Corporation in
Western Australia.

¦	Turf plot irrigation using
the sensor resulted in
water savings of 25
percent compared to
those using the best
practice methods.

¦	No reduction in turfgrass
quality was observed.

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Study









Location





Study Findings(s)

Study

and/or

Product(s)



Relevant to Soil Moisture

Reference

Sponsor

Tested

Objective(s) of Study

Sensors

Blonquist et

Utah State

Acclima Digital

(1) To compare

¦ Relative to ET-based

al., 2006

University

TDT (Acclima

irrigation scheduling

recommendations, the



(Logan, Utah)

Inc.)

in turfgrass based on

system that included the







weather station ET

soil moisture sensor







estimates with those

applied approximately 16







from a time domain

percent less water.







transmissometry

¦ Relative to a fixed







(TDT) soil moisture

irrigation schedule, the







sensor.

soil moisture sensor







(2) To apply a

system applied







computer-based

approximately 53 percent







numerical model to

less water.







simulate volumetric









soil water content









dynamics at the









burial depth of the









sensor and any









drainage occurring









below the turgrass









root depth.



Shedd et al.,

University of

Acclima Digital

(1) To evaluate the

¦ The medium threshold

2007

Florida, Plant

TDT RS-500

differences in

settings for both soil



Science

(Acclima Inc.)

irrigation water

moisture sensors



Research



application and the

resulted in 11 percent to



and

LawnLogic

resulting quality of

28 percent water savings,



Education

(LawnLogic)

St. Augustine

without any significant



Unit (Citra,



turfgrass.

difference in the turfgrass



Florida)



(2) To test two types of

quality.







soil moisture sensor-

¦ The low threshold







based controllers set

settings for both soil







at three different

moisture sensors







moisture content

resulted in a 40 percent







thresholds.

to 63 percent water







(3) To test a time-based

savings, but did not







scheduling system

maintain acceptable turf







with and without a

quality.







rain sensor.

¦ The high threshold







(4) To test two types of

settings for both soil







evapotranspiration-

moisture sensor







based irrigation

treatments showed no







controllers.

reduction in water









applications.

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Study









Location





Study Findings(s)

Study

and/or

Product(s)



Relevant to Soil Moisture

Reference

Sponsor

Tested

Objective(s) of Study

Sensors

Cardenas-

University of

Acclima Digital

(1) To quantify the

¦ Water savings ranged

Laihacar et

Florida

TDT (Acclima

differences in

from 27 percent to 92

al., 2008

(Gainesville,

Inc.)

irrigation water use

percent for the four



Florida)



and turf quality

sensors studied





Watermark

between soil

compared to the control,





200SS-5

moisture sensor-

with an average savings





(Irrometer

based irrigation

of 72 percent.





Company Inc.)

systems versus time-

¦ Water savings were







based systems

dependent on the





Rain Bird MS-100

during wet weather

frequency of scheduled





(Rain Bird

conditions.

irrigation and the choice





International

(2) To test the different

of technology.





Inc.)3

commercially

¦ No differences in







available soil

turfgrass quality were





Water Watcher

moisture sensors.

visible.





DPS-100 (Water

(3) To test a time-based







Watcher Inc.)3

scheduling system









with and without a









rain sensor.



McCready et

University of

Acclima Digital

To evaluate the

¦ Reductions in irrigation

al., 2009

Florida

TDT RS-500

effectiveness of soil

applied were as follows:



(Gainesville,

(Acclima Inc.)

moisture sensors, ET

7 to 30 percent for rain



Florida)



controllers, and rain

sensors, 0 to 74 percent





LawnLogic

sensors at controlling

for soil moisture sensors,





LL1004

irrigation and

and 25 to 62 percent for





(LawnLogic)

providing adequate

ET controllers.







turf quality.

¦ The soil moisture sensor









treatments at low









threshold setting resulted









in high water savings but









unacceptable turfgrass









quality.









¦ The soil moisture sensor









treatments at the medium









threshold produced good









turfgrass quality and









reduced irrigation water









use by 11 to 53 percent.









¦ The soil moisture sensor









treatments at the high









threshold reduced water









use by 0 to 14 percent.

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Study

Location

Study Findings(s)

Study

and/or

Product(s)

Relevant to Soil Moisture

Reference

Sponsor

Tested

Objective(s) of Study

Sensors

Cardenas-

University of

Acclima Digital

(1) To quantify the

¦ Water savings ranged

Laihacar et

Florida

TDT (Acclima

differences in

from 9 to 83 percent for

al., 2010

(Gainesville,

Inc.)

irrigation water use

the three sensors studied

Florida)

and turf quality

compared to the control,

Watermark

between soil

with an average savings

200SS-5

moisture sensor-

of 54 percent.

(Irrometer

based irrigation

¦ Water savings were

Company Inc.)

systems versus time-

dependent on the

based systems

frequency of scheduled

Rain Bird MS-100

during dry weather

irrigation and the choice

(Rain Bird

conditions.

of technology.

International

(2) To test the different

¦ No differences in

Inc.)3

commercially

turfgrass quality were

available soil

visible.

Water Watcher

moisture sensors.

DPS-100 (Water

(3) To test a time-based

Watcher Inc.)3

scheduling system

with and without a

rain sensor.

Commercial Field Studies

DeOreo and

(Boulder,

Watermark Soil

To determine how

¦ Water applications were

Lander,

Colorado)

Moisture Sensor

efficiently soil

similar to the theoretical

1994

(Irrometer

moisture sensors

applications.

Company, Inc.)

perform in the field.

¦ Water cost savings were

demonstrated in the

amounts between $1,000

and $3,000.

Notes:

a. Product is no longer available. The manufacturer has either gone out of business or the type of
soil moisture sensor is no longer made.

b. Product is a weather-based controller.

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APPENDIX B: Research Proposal for Soil Moisture-Based Control

Technologies

I. Background

To address irrigation scheduling inefficiencies and water waste, the U.S. Environmental
Protection Agency's (EPA's) WaterSense program is interested in labeling efficient
irrigation system control technologies. In 2011, EPA released the WaterSense
Specification for Weather-Based Irrigation Controllers. EPA issued a Notice of Intent
(NOI) on May 16, 2013 announcing its intent to add soil moisture-based control
technologies to its suite of WaterSense labeled products.

Soil moisture-based control technologies make irrigation schedule adjustments by
automatically tailoring the amount and/or frequency and timing of irrigation events based
on the moisture content of the soil in the landscape. There are currently two types of soil
moisture-based control technologies: bypass (i.e., watering interruption) technologies
and on-demand technologies.

The American Society of Agricultural and Biological Engineers (ASABE) is developing
two standards for these products: S633, Testing of Soil Moisture Sensors for Landscape
Irrigation, and S627, Standardized Testing Protocol for Weather-based or Soil Moisture-
based Landscape Irrigation Control Devices. The ASABE S633 Committee is working to
include in the standard a test protocol for bypass technologies that will determine the
responsiveness of soil moisture sensors and their associated interrupt devices. ASABE
S627 focuses on the test protocols for weather-based irrigation controllers and on-
demand soil moisture-based technologies.

WaterSense is focusing its initial specification development efforts on bypass technology
because the fundamental aspects of the performance test protocol for that technology

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have been fully defined by the S633 Committee mentioned above. WaterSense plans to
address on-demand technology at a later date.

II. Objective

The objectives of this research proposal are twofold:

1. To evaluate and ensure that the performance test protocol for bypass type soil
moisture-based technology included in ASABE S633, Testing of Soil Moisture
Sensors for Landscape Irrigation, is repeatable among independent laboratories.

2. To provide performance data that could inform the establishment of performance
level thresholds for bypass type soil moisture-based technologies.

The research approach outlined below provides a mechanism to generate vital data that
will allow WaterSense to move forward with its specification development efforts more
quickly and with the necessary assurance to provide for and maintain the integrity of the
WaterSense label.

III. Approach

Assessing Test Protocol Repeatability

To assess the performance test protocol repeatability, three independent laboratories
will conduct round robin testing of a representative set of bypass type soil moisture-
based control technologies on the market using the performance test protocol under
development by the ASABE S633 Committee. Other laboratories and manufacturers
participating in the S633 Committee will also be encouraged to voluntarily participate in
the round robin testing to augment the data set. All round robin testing data generated
will be aggregated, masked, analyzed, and reported back to the committee for
consideration. The committee will then use the data to make adjustments to the test
protocol as necessary to ensure that independent laboratories can achieve similar
results. It should be noted that in order for this research to proceed, the committee will
need to be at a point where the protocol is ready for round robin testing.

Establishing Performance Thresholds

The data generated from the round robin testing will also be used to assess the range of
performance that is achievable for the products on the market. These data will inform an
appropriate threshold for product performance. The threshold will consider both the top
echelon of products on the market and the minimum performance level that is necessary
to ensure the products can accurately sense the moisture content of the soil and serve
their intended function.

For more information on this research proposal please send an e-mail to: watersense-
products@erq.com

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