Step-by-Step Guide
Understanding the Depletion Model
WeatherTRAK uses a calculated soil depletion model that operates on a station-by-station basis for every station you manage. The best way to understand this concept is to imagine a glass of water under every zone in your system. This glass represents the available water in the soil, and it fluctuates between full (0% depleted) and empty based on weather conditions and irrigation events.
On a rainy day, the glass fills up as moisture is added to the soil. On a sunny day, the glass depletes as water evaporates from the soil and is consumed by plants. WeatherTRAK continuously monitors this depletion for every station. Once the depletion passes a threshold called the Maximum Allowable Depletion (MAD), the system prompts irrigation to refill the glass of water back up. The system operates within a range from 50% depleted to 0% depleted (completely full).
Understanding this depletion model is fundamental to using WeatherTRAK effectively. If this concept sinks in, you'll understand how to adjust your irrigation frequency with confidence.
Adjusting Target MAD (Maximum Allowable Depletion)
The target MAD setting determines the trigger point at which irrigation will occur, and it directly affects the frequency of your watering schedule. Within WeatherTRAK, you can adjust this trigger point from 80% down to 20%, though 50% is the recommended setting for most applications.
Here's how target MAD affects frequency: If you adjust your target MAD up to 60%, you're telling the system not to let the glass of water deplete all the way to 50% before irrigating. Instead, when the glass reaches 60% full, the system will prompt irrigation. A higher target MAD will prompt greater frequency in your irrigation schedule because you're watering before the soil gets as dry.
Conversely, if you set your target MAD to 40%, you're allowing the glass to get to 40% depleted before irrigation occurs. This increases the amount of time between irrigation events, resulting in less frequent watering. The lower the MAD number, the more frequent the irrigation; the higher the MAD number, the less frequent the irrigation.
It's very rare that you would need to be anywhere besides the default 50% setting. This is one of the primary tools for managing irrigation frequency in your system.
Selecting the Correct Soil Type
Soil type is another factor that directly affects irrigation frequency. WeatherTRAK offers several soil type options, and selecting the correct one is critical because different soils hold water differently and affect how long water stays available to plants.
Understanding Soil Characteristics: Sand allows water to travel through it very easily—you can think of it like water moving through boulders. Sandy soil has a fast infiltration rate but low water-holding capacity. Clay, on the other hand, holds water much longer. Clay soil has a much larger field capacity (the amount of water it can hold) and retains that water in the soil for a very long time.
This difference in water retention directly impacts frequency. With clay soil, you can push your irrigation days further out because the water stays available to plants longer. With sandy soil, water doesn't stay in the soil very long, so the days between irrigation events will shrink to meet the needs of the plants.
Field Testing Your Soil Type: There's a simple on-site test you can perform to determine your soil type. Dig down a decent amount in your soil and grab a piece of soil in your hand. Make sure it's a little bit wet (if it's dry, add a little water). Squeeze the soil in your hand and observe the indentation your fingers make. The amount of indentation will help you determine whether you have sand, loam, or clay. While this isn't a scientifically precise method, it's a good way to assess soil type on site.
Another method is the jar test. Grab a soil sample, put it in a jar, fill the jar with water, shake it up, and let it sit. You'll see the separation of different soil particles—the finer sediment settles on top and the larger pieces settle on the bottom.
How Soil Type Affects Irrigation Settings: Clay soil requires shorter cycles and longer soaks because water infiltrates more slowly, but you'll have more available water, which means you can go longer between waterings. Sandy soil requires longer cycles and shorter soaks because water infiltrates quickly, but the days between irrigation events will be shorter because the soil doesn't hold water as long.
Important: Don't adjust the soil type setting just to try to manage a frequency outcome. Make the information in the program match the actual conditions in the field, and let the WeatherTRAK science handle the rest. There are other ways to manage frequency (like adjusting target MAD), but soil type should always reflect reality.
More than 95% of stations will have the word "loam" in the soil type—whether sandy loam, loam, or clay loam. These are the middle three settings. Even though WeatherTRAK offers extreme settings for sand and clay, those represent extreme soil types. In Utah, for example, the vast majority of stations are set to clay loam. It's very rare to use anything besides one of the middle three loam settings.
Choosing the Appropriate Plant Type
Plant type is another way of assigning a crop coefficient to a station, and WeatherTRAK applies this on a station-by-station basis. When you tell WeatherTRAK that you have cool-season turf in a zone, the system applies a crop coefficient behind the scenes. This crop coefficient represents how much water that type of plant pulls out of the soil, and it directly affects irrigation frequency.
Every different type of plant pulls a different amount of water from the soil. Your shrubs pull a different amount of water than your grass does, and this difference affects how frequently you need to irrigate. This feature is particularly valuable for conservation-focused landscapes. If you design with plants that require less water, make sure you're scheduling them appropriately. Xeric gardens can be kept healthy on significantly less water when you select a plant type that reflects a lower crop coefficient.
Selecting Water Use Levels for Shrubs: A common question is when to pick high, medium, or low water use for shrubs. If you're not familiar with a specific plant, the best practice is to go middle-of-the-road and select medium water use. As a general guideline, think of tropical plants as high water use—these are plants that will burn through water quickly. Most plants in commercial and residential landscapes fall into the medium water use category. Low water use is appropriate for water conservation gardens, xeric gardens, or plantings that include cactus and similar drought-tolerant species.
💡One tip: if a plant has a woody stem—like lavender, rosemary, or similar plants—it may be a low water use plant, though this varies by species. If you know that a garden has been specifically designed with a focus on water conservation, you can typically use the low water use setting. When in doubt, medium is a safe choice.
Understanding Mix vs. Shrub: The "shrub" plant type is for areas with only shrubs. The "mix" plant type is for areas with a mixture of trees and shrubs together.
Custom Plant Types: For advanced users who want to dial in exact crop coefficients, WeatherTRAK offers custom plant and custom turf options. If you obtain specific crop coefficient data from your local university (many state universities provide this information), you can program those exact values into the system. This allows the science to reflect precisely what you're working with in the field.
Setting and Managing Root Depth
Root depth is the primary tool for managing irrigation frequency when you want to increase or decrease how often a station irrigates. Going back to the glass of water analogy, root depth sets the bottom of that glass. This is why getting root depth right is so important.
Measuring Root Depth: You can determine root depth fairly simply by using a soil probe. In grass areas, for example, insert the soil probe down into the soil, pull it back up, and observe how far down the roots have grown. This gives you an accurate measurement of the active root zone.
WeatherTRAK calculates the exact saturation point in the soil based on root depth. If you're growing roots down to four inches, water applied at the fifth inch is wasted water. The system isolates exactly where to hydrate to ensure you're only using the right amount of water and not wasting any below the root zone.
How Root Depth Changes Affect Frequency and Runtime
Understanding how root depth affects your irrigation schedule is critical.
Here's a detailed example of how this works:
Imagine you have a plant with a four-inch root depth. With all other factors combined (weather, soil type, plant type, etc.), that plant will need five irrigation events over two weeks, with each event lasting 10 minutes. Across those two weeks, you'll receive a total of 50 minutes of irrigation.
Now, all things being the same—the same weather pattern, the same station, everything identical—if you go into that station and change the root depth from four inches to two inches, the controller understands two things:
First, when it waters, it doesn't need to water as deeply. You no longer need to push water down four inches; you only need to push water down two inches.
Second, the controller knows that water in the top two inches will be consumed or evaporated significantly faster than it would have been if it were pushed down four inches.
When you make this change, you might see your schedule transform from five events at 10 minutes each to 10 events at five minutes each. You get greater frequency but shorter run times. However, across the board over those two weeks, it's the same total amount of irrigation—just delivered differently and optimized differently to keep saturation happening where you need it for those plants.
From the perspective of a water manager walking the site, you're going to see the station water very differently even though the total water applied remains the same.
Using Root Depth to Address High Depletion Alerts
Root depth adjustment is also a valuable tool during the heat of summer, especially in areas with water restrictions. If you're getting to your maximum allowable depletion and receiving station high depletion alerts before you can even irrigate, you can use root depth to help manage this situation.
Station high depletion alerts occur when the depletion level exceeds what's acceptable based on your root depth and other settings. If you're getting too frequent station high depletion alerts, try adjusting the root depth down an inch or two at a time until the system has enough time to catch back up. This gives you more frequent irrigation opportunities to address the depletion without violating water restrictions.
Training Root Depth for Long-Term Plant Health
Root depth management is also a strategy for ensuring long-term plant health, not just managing irrigation frequency. When you have newly established plant material—for example, a new turf panel sitting on loam—the contractor may be watering it frequently to pass their guarantee period. Initially, the roots might only be an inch or two deep.
Over time, you don't want those roots just sitting shallow, waiting for frequent irrigation like a hose every 15 minutes. You want to train them to find their own way and drive deeper into the soil. You can do this by gradually adjusting the root depth setting over time. You might start at two inches, then move to three inches, then to four inches over successive seasons.
You can see really healthy turf with roots that are anywhere from six to nine inches deep if you have well-established turf. One advanced user has trained his turf root depth down to 10 inches, whereas most users see their turf at about four inches. He accomplished this by continually bumping the root depth down one inch at a time, season after season, continuing to saturate underneath the roots and driving them farther and farther down into the soil. This makes the plant healthier and more drought-tolerant, able to sustain longer periods without irrigation because of those deep roots.
When you make these changes—for example, changing from a four-inch root depth to a five-inch root depth—you'll see changes in both frequency and runtime. You'll have longer runtimes to drive water further down into the soil, but fewer runtimes in between because it takes longer for that water to be consumed by the plant or evaporated by the weather.
Managing Water Day Alerts with Limited Watering Days
A common question is whether there's a way to eliminate inadequate water day alerts when there are limited water days allowed by the city. The short answer is no—WeatherTRAK is tracking the science, and the science may want more watering days than your restrictions allow.
The system will always abide by whatever water restrictions you have programmed in, so it will only water when you tell it it's okay to do so. WeatherTRAK won't leave you subject to fines and penalties that come with breaking water restrictions. However, water day alerts are a normal part of the process when restrictions limit your available watering days.
These alerts automatically clear when depletion levels return to acceptable levels. The system will dynamically adjust all of your stations to try and compensate for what's being missed on restricted days. The water day alert is simply informing you that the science wants more days than your water restrictions have allowed, and the system is working to optimize around those constraints.
Understanding the MAD Limit Switch
The MAD limit switch is a specific feature that should be left in the default setting for most applications. It's designed specifically for sports turf in high restriction areas.
In normal irrigation, when a station is at 70% depletion and WeatherTRAK irrigates, it will try to water that station all the way back to 0% depletion (completely full) every time. With the MAD limit switch enabled, the system never applies more than your target MAD in a single irrigation event.
For example, if you were at 70% depletion with a 50% target MAD, the system would only water 50% back, leaving you at 20% depletion to be made up at a future irrigation event. This prevents extraordinarily long runtimes.
The feature is meant to stop very long runtimes of rotors on turf fields when you have scheduled events constantly interrupting play and maintenance. Those long runtimes could create damage and plant health problems if they can't be completed. This is really a sports turf application, so unless you know you need this feature and understand its implications, leave it in the default setting.
Video Walkthrough
Video originally published April 2021.
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