Why is soil type and slope important?

The soil type / slope feature is the secret weapon of the SmartLine controller. Many people overlook this setting but it has a wonderful purpose – preventing runoff. Here are some definitions to help:

• RUN – the maximum run cycle the controller will accept.
• SOAK – the minimum amount of time the zone remains off before a new cycle starts.

This feature does not affect the overall amount of water that is applied, just how that water is applied.

SmartLine controllers have three soil selections (sandy, loam, clay) and a slope selection (0 degrees up to 25 degrees). The sole purpose of soil/slope is to tell the controller the zone-specific topography of the area so the controller can determine the best way to apply the irrigation cycle(s) to prevent runoff. Because of this feature there is no need to worry about multiple start times to cycle through or to figure the math of the total run time; SmartLine does it for you.

How Soil Type/Slope Settings Work

Here is a brief summary of how those settings relate and affect the operation of the controller: First, the controller looks at the sprinkler type to determine how fast the water is being applied for that zone. The controller applies the soil/slope settings to divide up the watering time to prevent runoff onto hard surfaces and loss of this water to your plants. Second, the controller optimizes the operation of the cycles to always have a zone watering during other zones’ soak cycles. This feature allows the controller to “jump” to the next zone ready to irrigate instead of always progressing though in numerical order. On smaller systems, or systems with high slopes, you will see the controller “jumping” around the landscape during the water cycles. This is normal and the controller is doing what it needs to do.

How Soil Types Relate

SANDY – sandy soils allow for longer run cycles and shorter soak cycles due to the faster infiltration rate of this type of soil. For example, a SPRAY on SANDY with 0-degree slope will run for 24 minutes per cycle maximum and soak (not come back on) for 18 minutes.

LOAM – Loam soils are between sandy and clay. These have reduced run cycles and longer soak periods, compared to sandy soils. For example, a SPRAY on LOAM with 0-degree slope will run for 15 minutes per cycle maximum and soak for 17 minutes. Loam is a very useful setting for pots, planters, and hanging baskets.

CLAY – Clay soils have the slowest infiltration rates and thus have the shortest run cycles. For example, a SPRAY on CLAY with 0-degree slope will run for 8 minutes per cycle maximum and soak for a minimum of 11 minutes.

How does this affect the overall operation of the controller? The only difference you will see is reduced runoff on your hardscapes and healthier plants.

Tips to Help with Soil/Slope

1. When in doubt, choose the slower infiltration rate soil.
2. When a zone is surrounded by concrete or other impervious material, exaggerate the soil and slope to help prevent runoff. For instance, parking islands are normally very flat but are surrounded by concrete. Try increasing the soil and increasing the slope to allow the controller to provide irrigation in small amounts to prevent wasteful and unsightly runoff through a parking lot.
3. You can see how your settings relate to the operation in ADVANCED>REVIEW>RUN/SOAK. You will also see a RUN/SOAK in the main menu options of ADVANCED; we will touch on that in another post. This setting applies to standard mode and is a global setting by program.
4. Once you have programmed the controller in auto adjust, even if you return the controller to standard mode, the controller will still use these settings to prevent runoff. Think of it as a little helper to manage and prevent wasteful irrigation.
5. When an area is relatively flat but has one section with a slope, it is always best to set the slope setting for the greatest slope in a zone.