Erroneous irrigation calculation settings for Rachio 3

I have a gen 3 Rachio and I have set up a zone which is set up to use an ET0 based daily schedule. I manually entered the zone details using the ‘Advanced settings’ as follows (screenshot below).

Available Water - 0.12in/in
Root depth - 10 in

This should result in every irrigation event to top up the soil moisture for the zone to at least 1.3 inches of water(I’ve set up efficiency to be 90%). Yet the Rachio seems to think that the soil moisture needs to be only about 0.6inches for 100% moisture. (screenshot below). In addition, when it irrigates, it doesn’t even try to get the soil moisture up to 100%. Even for 0.6 inches, it shuts off after getting the moisture level to 0.46in. I’m trying to figure out what I’m doing wrong or if it is a bug.

Other zones have also settings that does not seem to make sense. I’ve been redoing all my irrigation zones and I’m wondering if something went wrong in the software during the process or if I’m missing something crucial.

Things look correct according to this chart. One thing to note is we can rarely water up to 100% since ET for the day will always draw down the soil moisture.


@franz, I missed the 0.6 inch irrigation event and the et0 draw down for the day resulting in less than 100%. So my second question was not really valid and can be discarded. Thanks.

Regarding my first question, the irrigation volume calculation is independent of ET0 and should only depend on the volume of soil and the PAW metric. In my case.
PAW/inch = 0.12 inches
Root depth = 10 inches
ergo -> 0.12inches * 10inches = 1.2 inches based on a simple calculation, while the rachio is only putting out 1/2 of the water (since the previous day, soil moisture was at 0%). Am I incorrect?

My theoretical understanding is that the full amount of PAW should be available to the plant roots and should be put out as such.

Field capacity is MAD * AWC * RZD.

This is a good paper on the topic.


Yes, my understanding of the theory is correct based on the paper.

I think I’ve figured out where the discrepancy comes from. It looks like I misinterpreted the moisture balance graph that Rachio shows. What the rachio calls moisture balance in the graph is different from what I interpreted the graph to show. I had expected the 0% to refer to 0% of the total AWC (the PWP). So the MAD of 50% would be indicated in the middle of the graph based on my interpretation (see screenshot below of what I was expecting). But it looks like the min/max in the graph are the MAD limits. I probably didn’t RTFM enough. I guess it all makes sense now. Thanks for the responses which eventually led me to the answer. :slight_smile:

Exactly, 0% isn’t PAW, it the bottom of your allowed depletion. Definitely confusing. There is probably a better way for the software to draw that graph.



The one thing I’m still not clear about is if the Rachio would do a full scale irrigation on a zone the very first time a zone is activated. This would be assuming a 0% AWC (i.e the soil water deficit is 100% of AWC). MAD should not be a factor the very first time.

I have a 50% MAD zone which used to be deactivated in the Rachio and had bone dry soil. I activated it yesterday and added it to my pre-existing flex daily schedule. It looks like the Rachio only added 50% of the required irrigation overnight and said it was now at 100%. Rachio apparently considered it as a normal ‘top up’ and assumed that the soil only had a 50% Soil Water Deficit. So I had to do an additional quick run for an equal amount of time to bring the ‘real’ AWC upto 100%. This doesn’t seem correct to me.

On new controller activations we assume each zone is depleted (0% of MAD).

With existing zones we continually track soil moisture even if the zone is not in a flex daily schedule. The zone could have had a (+) amount of soil moisture hence the top off?


My controller was originally activated last year and I had set it up with only a few valves and zones. Yesterday, I added a new valve and zone (Zone 12 which had been deactivated before - not sure if deactivated zones are tracked for moisture). It ran for 72 minutes which corresponded to 50% MAD for my zone setup . I verified that no other irrigation events had happened before (other than extremely short test runs for valve connections and flow calibration)

So if the Rachio assumes 0% existing PAW only for new controller activations, and not for activation of earlier unused zones, it would explain why it did only a 50% MAD irrigation top off. Intuitively, I would have expected and wanted a 100% full irrigation so that the whole RZ is at FC.