Soil Moisture 0% All Zones

Yesterday and today the controller put 10 gpm for 37 minutes on all zones with a Daily Flex schedule.

I walked the yard at 6 am and it is wet all around. But app shows soil moisture of all zones at 0%.


That’s the prediction of what the soil moisture will be at the end of the day.

If you Allowed Depletion is 50%, then if it’s under that, it should water next cycle?

There are three percents that we either see or can think about:

Let’s assume a zone can hold 1" of water (Soil Available Water x Root Depth).

Allowed Depletion Percent is the percent of the water that a root depth of soil can contain which is allowed to be used (depleted) before wilting is imminent and watering should be done. For this example, that’s 50% of 1" or 0.5" of water. Of the 1" of total water available, we want to use only half of it before we water again.

Actual Percent of water left in the zone upon wilting/watering (not usually shown) is all the water minus the Allowed Depletion, normally 100% - 50% = 50%. I this case, the same at 0.5". If we had 40% Allowed Depletion then there is 60% of the total water left when we want to water.

The Zone Moisture shown for each zone represents the percent of the Allowed Depletion which is remaining (yeah, kind of a percent of a percent). This is not a percent of the TOTAL water, but of the Allowed Depletion. For example, if the 1" of water is down to 0.8" of water, this is (0.8 - 0.5) / (1.0 - 0.5) = 0.6 or 60% Moisture. That’s not 60% total, but you still have 60% of the Allowed Depletion left. This value is shown, more or less, for the time of day being viewed, so may or may not include watering done or to-be-done, and ET used or not-used.

The Zone Moisture in the graph is considered at the end of the day, is calculated the same way as above, but DOES consider the total of any irrigation or rain received as well as the ET used for the day.

To answer your question, the next water cycle should occur on the next day where the Moisture Level would be zero or less after subtracting the ET value. In the above case, this is when the total water in the zone would be 0.50" or less.

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Excellent detail, thanks.