Commercial Horticultural Field Specialist
Iowa State University Extension and Outreach
Connected devices are becoming the norm in households including everything from outlets and switches to lightbulbs and sensors for water leaks. The horticulture industry has not been left out of the connected devices revolution. New irrigation and climate controllers offer remote management from your phone or tablet giving you the ability to irrigate a field or close up a high tunnel from anywhere with internet or cellular connection.
Irrigation controllers are a tool that I rarely see used in the Iowa produce industry. However, irrigation is a farm task that can be automated requiring only minimal input and observation to adjust on a weekly basis. They do not need to be expensive, complicated, or difficult to install. More advanced systems can be connected to rain sensors or soil moisture sensors to automatically delay an irrigation cycle. The newest systems can be connected to a weather station or weather source via the internet. These connected systems can be accessed through your computer, cell phone, or tablet and can automatically adjust run times based on environmental conditions such as rainfall, soil moisture, and temperature.
To get started setting up an irrigation controller, lets define a few common irrigation terms:
- A controller is the brain of the system but it is nothing more than a fancy programmable clock. It opens and closes valves according to a schedule programed by the user.
- Valves determine where water flows. Most valves are two pieces; an electric solenoid connected to the controller with a valve body which water flows through. Most home and small commercial grade controllers can operate only one valve at a time.
- A Zone is all the water that flows from a single valve to the field. A zone must be sized so that the total amount of water flowing to the field is less than the total amount supplied by the source.
- A pump start relay is a switch that turns on an auxiliary pump. This is not needed when irrigating from a rural water source or most standard home wells with an always-on pressure. It is directly connected to the controller via a communication wire.
A basic irrigation system only needs a controller, a couple of irrigation valves, a backflow prevention device, and a filter. If electricity is not nearby, battery-powered controllers (such as the Hunter NODE-100 and Rainbird ESP-9V) are available to operate the valves. To install an irrigation valve, plumb it inline between the water source and the zone. Placing a union fitting on both sides of the valve to make it easier to replace when the valve inevitably wears out. Wiring an irrigation controller is just as simple. A solenoid has two wires. One wire goes to the common terminal on the controller and one wire goes to a zone terminal on the controller. Generally, it does not matter which one is which but always read and follow the controller instructions before installing. When connecting multiple valves to an irrigation controller, the common wires are all connected together. When connecting multiple valve to an irrigation controller, multi strand wire is used to keep the wire clutter better organized. The number of wire strands needed equals the number of valves plus one (for common) though it is a good idea to have a couple of extra strands for future growth or if a single strand goes bad the entire system does not need to be rewired. Cost for a basic irrigation controller that can operate multiple zones is as low as $50 with valves starting around $15 each.
Many new irrigation controllers can accommodate a rain sensor. When activated, a rain sensor will delay an irrigation cycle for a user-programmed length of time. Typically 1 to 3 days. This is a helpful feature when irrigating outdoor crops but caution should be used when a controller is managing irrigation for outdoor crops in conjunction with a high tunnel as not all controllers are to able distinguish which valves to delay and which not to delay. For some controllers, the delay is all valves or no valves.
Several products such as the Hunter phc-1200i, Rachio 3 Smart Sprinkler, Rainbird ESP-Me series, Orbit B-hyve, and Gro Controller by Scotts offer internet connectivity. Cost for these system vary from $150 to $300. Features vary from manufacturer to manufacturer but some premium features include:
- Remote connectivity. Program and access the system from your computer, tablet, or cell phone. Turn on/off a zone or adjust the schedule from anywhere with an internet connection.
- Automatic adjustment of run times based on local weather data. Some connected systems can automatically adjust the run time of each zone based on weather variables such as temperature or rainfall. When temperatures are hot, more water is applied by increasing run time. When temperatures are cool, plants need less water so the amount of water applied is reduced by decreasing the runtime. Furthermore, an irrigation cycle can be delayed similar to a rain sensor but the delay can be set to dictate how much rain must be received before a delay is initiated. The added value of this feature is that trace rainfalls (such as a couple of tenths in the morning) do not delay an irrigation cycle. Only significant ones do. Weather station network availability varies from manufacturer to manufacturer. Some work with vast networks such as weather underground (which allows you to connect to your own local station) and some have limited station availability. The value of automatic adjustment of run times is directly related to the quality of the local station that is connected to the controller and the ability of the user to finely tune settings for their need.
- Create program water schedules. A program water schedule is used to assign multiple valves the same irrigation scheme. This feature is especially useful when managing the same crop across multiple valves. For instance, a farm has one zone for tomatoes and three zones for muskmelons (controlled by three different valves). A single muskmelon schedule is assigned to each of the three muskmelons valves. A change to the muskmelon schedule is made across all three muskmelon zones rather than making three separate changes. This feature ensures that changes are done across the board for like crops. The program water schedules are saved and assigned to valves the following year.
- Alerts. Did something go wrong? The station will tell you. Some controllers have the ability to monitor a flow meter that connected to the station. The connected flow meter helps determine if there is a leak or clog somewhere in the system and notifies you that there is a problem. A master valve is also a good investment so the whole system can be turned off. Master valve’s act as a backup valve or fail-safe valve if something breaks on a zone valve.
- The cycle and soak feature enables a grower to reduce run-off and wasted water on soils that have slow penetration like clay soils or reduce leaching on course soils like sand. It is also good for young plants that have shallow root systems. However, don’t forget to increase the length of the cycles as the plants age to encourage deep root growth.
Choosing an irrigation controller
Choose an irrigation controller made from a well-known, reliable manufacturer. It should be easy to connect the valves and easy to program. If it is not easy to use, it will not be used. A controller should have the ability to control as many zones as needed plus a few extra to allow for future growth. If purchasing a connected controller, download and test the application as well as the web interface to ensure it suites your needs and works with your devices.
Irrigation controllers help to reduce effort while automating an irrigation system. However, it is still up to the user to monitor plants and make regular adjustment to the schedule to ensure the appropriate amount of water is applied. This means regularly scouting soil moisture and adjusting run times as needed.