Smart Irrigation Technology: Controllers and Sensors

Introduction

Rainfall in Oklahoma is variable across the state and fluctuates by year.  During dry periods, irrigation may be needed to preserve landscape quality.  Over- or under-irrigating a landscape can possibly increase disease incidence, waste water and decrease overall landscape condition.  Irrigation system efficiency is dependent upon several factors including design, installation and specific site conditions. Water applied to a landscape can account for a significant portion of a property’s water use. In Oklahoma, outdoor water use accounts for approximately 30 percent to 50 percent of household water use. A substantial amount of water is lost to evaporation, wind and runoff as a consequence of improper watering methods.  Reducing or eliminating this loss decreases utility bills and creates a more water efficient, healthy landscape.

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Outdoor water savings can be achieved using smart irrigation technologies. Smart irrigation controllers and sensors have been developed to reduce outdoor water use by irrigating based on plant water need compared to traditional automatic system timers, which irrigate on a user-determined fixed schedule. This technology exists as a complete controller or as a sensor that can be added to an existing irrigation timer to create a smart controller.  Smart irrigation technology uses weather data or soil moisture data to determine the irrigation need of the landscape. Smart irrigation technology includes:

These products maximize irrigation efficiency by reducing water waste, while maintaining plant health and quality. Incorporating smart irrigation technology in the landscape can potentially reduce outdoor water consumption. This technology is appropriate for small, residential landscapes as well as large, managed landscapes. The following sections describe how each product functions and the advantages and disadvantages of each product.  Irrigation managers and homeowners should be aware that smart irrigation technology will need to be periodically adjusted and maintained for maximum water savings.

Smart Irrigation Technology: New Controllers

There is a broad spectrum of smart irrigation technology that consumers can benefit from utilizing. Choosing the correct technology for the situation is essential to achieve potential water savings. Watering restrictions exist in some areas of Oklahoma, so the irrigation timer may be adjusted for allowed watering days. Irrigation controllers can be separated into two main categories: Climate based controllers and soil moisture based controllers.

Climate-Based Controllers

Climate-based controllers also referred to as evapotranspiration (ET) controllers use local weather data to adjust irrigation schedules (Figure 1). Evapotranspiration is the combination of evaporation from the soil surface and transpiration by plant materials.  These climate-based controllers gather local weather information and make irrigation run-time adjustments so the landscape only receives the appropriate amount of water.

There are three basic types of ET controllers:

• Signal-based controllers use meteorological data from a publicly available source and the ET value is calculated for a grass surface at the site.  The ET data is then sent to the controller by a wireless connection.
• Historic ET controllers use a pre-programmed water use curve, based on historic water use in different regions.  The curve can be adjusted for temperature and solar radiation.
• On-site weather measurement controllers use weather data collected on-site to calculate continuous ET measurements and water accordingly.
  
  

Evapotranspiration controllers have been shown to reduce outdoor water use. In Las Vegas, Nev., homes with ET based controllers saw an average of 20 percent irrigation reduction compared to homes with homeowner-scheduled irrigation (Devitt et al., ). Additionally, a study conducted on St. Augustine turfgrass showed an average irrigation savings of 43 percent in the summer compared to homeowner-scheduled irrigation, with no reduction in turfgrass quality (Davis et al., ). The accuracy of ET controllers depends on the equation parameters. Most ET controllers cost between $250 and $900. Professional grade ET controllers range between $900 and $2,500.

Figure 1. Evapotranspiration based controller. Photo courtesy of Rainbird.

Soil Moisture Sensor Controllers

The second type of smart irrigation controllers includes soil moisture sensor controllers (Figure 2).  Instead of using weather data, soil moisture sensor controllers utilize a soil moisture sensor placed belowground in the root zone of lawns to determine water need.  The soil moisture sensor estimates the soil volumetric water content.  Volumetric water content represents the portion of the total volume of soil occupied by water. The controllers can be adjusted to open the valves and start irrigation once the volumetric water content reaches a user-defined threshold.  The appropriate threshold value depends on soil and vegetation type and usually ranges from about 10 percent to 40 percent.  Soil moisture sensors must be installed in a representative area of the turf; far enough from sprinkler heads, tree roots, sidewalks and walls (Figure 3).

Similar to ET controllers, soil moisture controllers have been shown to reduce irrigation, while maintaining turfgrass quality. Compared to homeowner irrigation schedules, soil moisture controllers had an average 72 percent irrigation savings and a 34 percent water savings during drought conditions (Cardenas-Laihacer et al., ; Cardenas-Laihacer et al., ).  In some cases, studies have shown smart controllers will increase water use at sites that typically use less than the theoretical irrigation requirement (Mayer and Deoreo, ). Typically, soil moisture sensor controllers range from $280 to $1,800. Difference in pricing depends on product manufacturer and end user, either residential or commercial customers.

Figure 2. Example of a soil moisture controller.

Figure 3. Ideal locations for soil moisture sensor placement.

Smart Irrigation Technology: Add-on Sensors

In many cases, a scheduling irrigation controller is already in use on a property and upgrading to a smart controller is impractical. To increase efficiency of automatic irrigation systems a soil moisture, rain, wind or freeze sensor can be added to upgrade the existing system. Some manufacturers produce devices capable of measuring multiple environmental elements using one apparatus. Many sensors are compatible with existing systems, easy to install and produce similar results to smart irrigation controllers. The add-on sensors are generally more affordable than smart irrigation controllers, assuming a compatible irrigation timer is already installed on site.

Soil Moisture Sensors

Soil moisture sensors can be connected to an existing irrigation system controller. The sensor measures the soil moisture content in the root zone before a scheduled irrigation event and bypasses the cycle if the soil moisture is above a specific threshold. Different types of soil moisture sensors are available and the consumer should ensure system compatibility before purchasing a sensor. Some soil moisture sensors include a soil freeze sensor that will interrupt the irrigation cycle if temperatures fall below 32 F. Soil moisture sensors are available as wired or wireless systems. Typical cost for a soil moisture sensor can range from $99 to $165.

Rain and Freeze Sensors

Although these sensors are not considered smart technology, rain and freeze sensors interrupt the irrigation cycle during a rain or freeze event when irrigation is unnecessary. Watering during the rain wastes water, money and causes unnecessary runoff. Three different types of rain sensors are available and each function is based on separate concepts.

• The original type of rain sensor still in use today works with a small cup or basin that collects water, once a pre-determined amount is collected, the weight of the cup interrupts the irrigation cycle (Figure 4). Debris in the cup can also interrupt the irrigation cycle and should be checked and cleared of litter periodically.
• The second type of rain sensor uses a dish with two electrodes that are a specific distance from the bottom of the cup.  The distance can be adjusted to allow for small rain events and similar to the first type of rain sensor, debris can reduce accuracy by displacing water in the cup.  When the water reaches the electrodes, the irrigation cycle is interrupted.
• The third type of rain sensor does not have a rain catch cup, which makes it low maintenance and reliable.  Instead, the sensor uses several disks that expand as they get wet (Figure 5). The expanded disks trigger the switch and interrupt the cycle. The system will resume the scheduled cycles once the disks dry out. The disks should be checked at least once a year to determine if they need to be replaced. All of the devices should be mounted in an open area where they will receive rainfall.
  
  

Potential water savings depends on the amount of rainfall in any given year.  During years with average to above average rainfall, water savings are more significant than during dry years.  Rain sensors have shown payback periods of less than a year, but should be monitored for optimum performance (Cardenas-Laihacar and Dukes, ).

As an example, if a homeowner’s irrigation system waters a ¼-acre yard and applies 1 inch of water each irrigation cycle, then each cycle applies 6,789 gallons of water. If water costs $5.00 per 1,000 gallons, the monetary savings will be $33.95 each time the irrigation cycle is interrupted during a rainfall event.  Considering each rainfall event, the homeowner could expect substantial water and money savings.  Most wireless rain sensors are more expensive and range from $120 to $200, while wired rain sensors cost approximately $30 to $50.

Freeze sensors interrupt an irrigation cycle when air temperatures fall below 32 F.  Eliminating irrigation during freezing temperatures can potentially extend irrigation system life and prevent sidewalks and streets from icing over, causing dangerous situations. Many rain sensors include a freeze sensor and homeowners should account for sensor capability when considering price.

Figure 4. Rain sensor with a small basin to collect rainfall.

Figure 5. Rain sensor attached to a gutter (top) and the inside of an expanding disc rain sensor (bottom). Photos courtesy of Hunter Industries.

Wind Sensors

Oklahoma has an average wind speed of 16 miles per hour (mph) with wind gusts from 20 mph to 30 mph. Watering during windy conditions reduces irrigation distribution uniformity across the landscape and decreases the amount of water infiltrating into the soil profile (Figure 6). Wind sensors interrupt the irrigation cycle if wind speed exceeds a specific threshold (Figure 7).

Smart irrigation technology may help reduce water waste, while also providing a healthy, attractive landscape. Irrigation system owners should provide regular maintenance and ensure the irrigation system is only watering the landscape when needed. Many wind sensors are around $80 to $100 dollars or are packaged with other sensors.

The Environmental Protection Agency (EPA) has created performance criteria for irrigation technology manufacturers under the WaterSense program. For more information go to: www.epa.gov/watersense/.  Often, it depends on consumer preference when deciding which irrigation controller or add-on sensor is appropriate for the end user. Many local irrigation distributors have smart irrigation technology available for customers.

Figure 6. Irrigating during windy conditions wastes water and reduces system efficiency.

Figure 7. Example wind sensor for use in the landscape. Photo courtesy of Hunter Industries.

References

Cardenas-Lailhacar, B., M. D. Dukes, and G. L. Miller. . Sensor-based automation of irrigation on bermudagrass, during wet weather conditions. Journal of Irrigation and Drainage Engineering. 134(2): 120-128.

Cardenas-Lailhacar, B. and M. D. Dukes. . Expanding disk rain sensor performance and potential savings. Journal of Irrigation and Drainage Engineering. 134(1):67-73.

Cardenas-Lailhacar, B., M. D. Dukes, and G. L. Miller. . Sensor-based automation of irrigation on bermudagrass, during dry weather conditions. Journal of Irrigation and Drainage Engineering. 136(3): 184-193.

Davis, S. L., M. D. Dukes, and G. L. Miller. . Landscape irrigation by evapotranspiration-based controllers under dry conditions in southwest Florida. Agriculture Water Mgmt. 96(12): -.

Devitt, D. A., K. Carstensen, and R. L. Morris. . Residential water savings associated with satellite-based ET irrigation controllers. Journal of Irrigation and Drainage Engineering. 134(1): 74-82.

Mayer, P.W. and Deoreo, W.B. . Improving urban irrigation efficiency by using weather-based “smart” controllers.  American Water Works Association.  102(2):86.

Malarie Gotcher

Extension Associate

Saleh Taghvaeian

Irrigation Extension Specialist

Justin Quetone Moss

Turfgrass Research and Extension

Smart irrigation does so much more than just helping to cut down your irrigation costs. Concerns over water scarcity and the landscaping health benefits of efficient irrigation are also making property owners take a closer look at smart irrigation.

Are you curious about how smart systems lower costs and reduce water waste on commercial properties? Partly through innovative sensors we’ll discuss in detail in this article. Another key aspect are the real-time adjustments, without manual human intervention, that produce major benefits, like the ones outlined in the following case study.

If you want to learn more, please visit our website Smart Irrigation System equipment(ar,ru,fr).

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University Research Park: Their investment in smart irrigation technology paid for itself within the first season. The Research Park saved 25 million gallons of water and $120,000 on water bills across 55 acres of landscaped gree spaces. 

As impressive as those savings are, we think you’ll find even more evidence in this article that smart irrigation is a necessity for today’s commercial properties. If you’re facing utility bills that continue to climb, and water utilization compliance is getting trickier, even if you’re in an area not known for drought, then continue reading. We’re here to help.

What’s ahead in this article:

• How Smart Irrigation Works
• Proven Smart Irrigation Technologies for Water Conservation
• Cost Savings and ROI of Smart Irrigation Systems
• Evaluating Your Property for Upgrading to Smart Irrigation

How Smart Irrigation Works: Technologies that Drive Efficiency

Property managers and owners are often surprised at the amount of water they can save through smart irrigation because they’re unaware of the three-pronged approach to preventing water waste that the technology uses. Smart irrigation uses these three elements to create a water saving plan for your property’s landscape:

• Automation

• Real-time data

• Efficiency-focused design

Automation removes the manual labor required to schedule and adjust irrigation system settings. Manual adjustments slow the process of optimizing water use, while decreasing precision.

Real-time data, such as soil moisture and weather conditions, is fed into smart irrigation systems so they can adjust watering levels immediately. Plants benefit by avoiding both under watering and overwatering.

Finally, efficiency-focused design aims to avoid wasted water through evaporation, runoff, or inefficient spray patterns. That’s why drip irrigation, at the base of your plants, is a key feature that ensures plant roots receive water directly, further lowering irrigation costs.

Proven Smart Irrigation Technologies for Water Conservation 

Now let’s look at four of today’s top technologies leading the charge in water conservation. It all begins with innovative sensors.

#1 Rain Sensors: Preventing Unnecessary Watering

How do rain sensors save water in irrigation? 

Rain sensors detect precipitation and automatically pause scheduled irrigation schedules, ensuring systems don’t operate during or immediately after rainfall, conserving water, and preventing overwatering. 

Although the process can seem technical, rain sensors simply send a signal to the system’s control box to “not water” once the sensors accumulate a set amount of rainfall. There are wired rain sensors, which are more cost-effective and usually need less maintenance. There are also  wireless sensors, which naturally offer flexibility in initial placement and can easily be relocated if needed.

Sensors come in a couple of other categories too:

• On-site rain sensors are installed on the property, collecting real-time weather data as it happens on the site. The main advantage is immediate, accurate data.
• Signal-based sensors get their weather data from external sources, like local weather stations. The main advantage to signal-based sensors is not needing to install and maintain the sensors on your property.

Regardless of the sensor type, the benefits are impressive:

• Reduced irrigation costs for property owners
• Prevents oversaturating landscape elements
• Avoids under-watering plants and trees
• Reduces wasted natural resources
• Adheres to sustainability initiatives 

#2 Rotary Spray Nozzles: Reducing Runoff and Improving Absorption

Modern rotary spray nozzles offer a win-win for property owners and managers. They deliver water slowly, which is ideal for soil to absorb water, while reducing the potential for wasteful runoff. Of course, your landscaping provider should ensure each irrigation zone is set up for success. 

With this approach, you want to avoidt the wrong mix of plant materials in a single zone together. Various plant species have different water requirements and mixing them in the same zone will lead to some plants getting too much moisture as others will receive too little.

This common mistake both wastes water and leads to unhealthy plants, negating the benefits you were hoping to achieve in the first place.

What are the benefits of rotary spray nozzles?

• Ideal for large commercial green spaces
• Promotes proper moisture absorption in the soil
• Precision watering helps avoid plant stress that can lead to dying plants
• Helps fend off disease and weeds
• Avoids water waste from runoff
• Highly adjustable output (can vary the arc and spray distance without tools)
• Large droplets are more wind-resistant (results in precision watering)

#3 ET Sensors & Smart Controllers: Adjusting Irrigation Based on Real-Time Weather

Evapotranspiration (ET) sensors are a cutting-edge irrigation technology. It’s impressive enough that these sensors accurately monitor humidity, temperature, wind, and rainfall. But then they use that data to calculate the resulting water lost by plants and soil due to these environmental factors.

Smart irrigation controllers are then triggered by the ET sensors to automatically adjust irrigation schedules. This means, even pop-up thunderstorms or heavy winds that seem to come out of the blue can be adjusted by your smart irrigation system in the moment, using these sensors.

ET sensors and smart controllers work in tandem to keep your commercial landscape properly watered. But these following benefits tell the full story:

• Minimizes the need for manual system adjustments
• Simplifies local water regulation compliance 
• Conserves water, improving brand image via sustainability efforts
• Financial savings through reduced water bills and irrigation costs
• Improved turf, plant, and tree health means reduced replacement costs

#4 Master Valves & Flow Sensors: Detecting Leaks and Preventing Major Water Waste

What role do master valves and flow sensors play in preventing water waste?

Master valves control the main water supply, shutting off flow in case of detected leaks. Flow sensors monitor water usage and identify irregularities, enabling prompt responses to leaks or system malfunctions—preventing significant water loss.

Typically installed after the backflow device, master valves are connected to the irrigation controller. As for flow sensors, they monitor in real-time, 24/7, and can detect the following:

• Breaks

• Leaks

• System malfunctions

These critical irrigation system elements are a property owner’s best ally in defending against major water waste and damage. Undetected leaks would otherwise waste hundreds or thousands of gallons of water. Not only would that skyrocket the water bill, but is likely to damage sections of your landscape.

Further, master valves and flow sensors mean your irrigation system will hold up longer by avoiding issues like excess water pressure and erratic fluctuations. Then there are also the reduced irrigation costs through efficient system operation to consider. A smart irrigation system gives itself constant “check-ups” that help prevent major problems.

Many Yellowstone Landscape customers have even found smart irrigation makes it easier to stay within local water conservation guidelines (which often gives them the bonus of rebates and incentives).

So let’s explore the ROI around your investment in smart irrigation.

Cost Savings and ROI of Smart Irrigation Systems

The following case study paints a great picture for the return on investment possible with smart irrigation systems.

An independent study in Northwest Arkansas, an area known for fluctuating rainfall from year to year, examined add-on rain sensors and soil moisture sensors and found that they reduced annual water use by an average of 22.1% and 66.2%, respectively over three years. The average ROI was estimated to be 87% for rain sensors and 200% for soil moisture sensors within the first year of installation.

And it isn’t only your water utility bill costs that will go down. Depending on your property’s size, your energy costs can also be reduced by an energy-efficient irrigation system. According to the Irrigation Association, utilizing smart irrigation and adhering to industry best practices can achieve up to 30% energy savings.

And with modern systems, you'll have less worry about maintenance and repairs since the system doesn’t run constantly. Remember, these systems are designed for efficiency, not just for more precise watering, but to reduce the run time of the system itself. 

The long-term irrigation savings with newer, smart irrigation systems are substantial compared to traditional systems:

• Up to half of all outdoor water use is wasted due to inefficient irrigation methods and systems (per EPA findings).
• Chances of landscape damage rise drastically with no leak detection in outdated systems (for example, costs to replace turf areas damaged by overwatering can be up to $4.50 per square foot).

Evaluating Your Property for Upgrading to Smart Irrigation

Ready to select the smart irrigation system best suited for your specific property and needs? Let’s take it step by step.

1. Evaluate your landscape into sections. Consider the varying water needs of turf, flower beds, trees, and shrubs.
2. Consider the growth stage of each of the above property sections.
3. Ask your provider about micro-climates that can affect watering needs.
4. Consider your water source options (i.e., municipal water, well, or rain harvesting system).
5. Compare smart irrigation system features like smart controllers, rain sensors, and soil moisture sensors.
6. Choose between on-site and signal-based sensors.
7. Decide on wireless vs. wired sensors to fit your property needs.
8. Consider your property size and layout to match the right system to optimize efficiency and give you flexibility for potential property changes in the future.

If you already have an irrigation system in place, you’re probably curious as to how well it’s performing. The best way to find out is by getting a water audit. A water audit will identify leaks, inefficiencies, and points where water is being wasted. 

Think of a water audit like a vehicle tune-up that improves fuel efficiency and prevents major breakdowns later on. Regular audits are a must if your goals include saving on irrigation costs, protecting water resources, and avoiding replacement of over or under-watered plants.

As you consider upgrading to a smart irrigation system or optimizing your current system, our team at Yellowstone Landscape is here to help. With years of experience in irrigation and an industry-leading sustainability knowledge base, we can guide you through the process and ensure you stay ahead of future water compliance challenges. Contact us today.

Conclusion

Smart irrigation is one of the most exciting development areas in modern landscape care. As you’ve learned, these innovative systems can positively impact property owners’ budgets. Utility bill savings are just the tip of the iceberg. Millions of gallons of water could be saved annually if all properties moved to smart irrigation systems and sustainable practices.

And with precision watering, property owners and managers don’t have the worries of improper water volumes threatening the health of valuable landscape elements. You can avoid the expense of replacing unhealthy plants, while enhancing your landscape’s curb appeal with healthy, vibrant, well-watered landscape features. 

These new irrigation technologies continue to evolve resulting in more attractive, resilient landscapes while making sustainability goals easier to achieve. Knowing which technologies are the best fit for your particular property is the most important part of the equation. 

A simple way to keep track of innovations that can save you money on the upkeep of your landscaping? Subscribe to our Yellowstone Landscape blog and get every update here first. 

Are you interested in learning more about drip irrigation products manufacturer? Contact us today to secure an expert consultation!