St Augustine - Sand Soil - Flex Daily Settings Questions

Hello, I’m located in Central Florida, slightly north of Orlando

We had to resod our entire yard, except the rear, so I have been researching like crazy to try and determine the optimal settings.

The new sod (St. Augustine) was put down around April 10, 2019 and we did the suggested new sod watering for the first 4 weeks or so.

Now that the sod is almost 2 months old, I am tweaking the Rachio and trying to set up a good Flex Daily.

Currently, I set the following and wanted to see if any suggestions. I was also thinking I should try to promote deeper roots, but I’m not sure if too soon or risky:

Available Water: 0.05 in/in, was set to 0.15 in/in until today since I checked survey (used the websoilsurvey website and it showed 0.05 cm/cm - 0.07 cm/cm)

Root Depth: 6 inches, was set to 5 inches until today (not sure if this is too deep for 2 month old St. Augustine, or if fine to help promote deeper roots?)

Allowed Depletion: 50% (should I try increasing to promote deeper roots or leave as-is since newer sod?)

Efficiency: Differs depending on zone, used Catch-Cup test (ranges from 60 - 75%)

Crop Coefficient: 65% for all (default)

Nozzle Inches Per Hour: Ranges depending on zone, used Catch-Cup test (0.33 in - 0.92 in)

Slopes: range from slight to moderate.
Exposure: Lots of sun
Soil Type: Sand

1 Zone is Rotor, other zones are spray heads (3 out of the 4 zones)

Thank you for any suggestions or help!

Everything seems fine except the soil. Sand shouldn’t even really be an option in the app. I would set it back to what it was before and see how your soil moisture watering graph looks like for the next two weeks. It will give you less watering frequency but deeper watering. If the yard gets stressed just increase the crop coefficient 5%-10% and it will increase frequency without duration.

:cheers:

Thanks! So change it back to 0.15 AWC? Assuming fine to leave on “sand” if changing under advanced. And it’s fine to change even though the websoilsurvey does say 0.05?

Also in addition to my last question. I did notice a couple of “dry spots” in various parts of the lawn (where the St. Augustine looks kind of straw-like/dried out). But I’m not sure if that is expected since it’s been very hot and dry here or if that means I should increase crop coefficient as you stated. Any thoughts?

Thanks

I’d change back to the soil type it was before to avoid confusion.

Can’t really help out there. To be honest if this is new sod I’d probably put most of the zones on a fixed schedule (maybe even flex monthly) and only try one zone, two at the most on flex daily. Once those zones are dialed in and you are happy with the results I’d move the rest over. Seems like your grass is still getting established. Just my two cents.

:cheers:

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I always had it set to Sand, in the past I set the Available Water to 0.15 but then when I did the soil test it said 0.05 so I had changed it just today to 0.05.

So you think change it back to Available Water of 0.15 or a different number there (I.e. maybe 0.10) since .15 wants to water one zone for 1 hour 45 min which seems possibly excessive (although it is a rotor zone)? Or change the soil type to something else, even though it is sand? The new sod did come with some dirt attached to it so perhaps that makes a difference also.

Sorry just want to make sure before doing anything. Thanks!

https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm - is what I meant by soil test up above.

Any idea on this?

I wouldn’t take soil tests as gospel, sometimes inaccurate due to a lot of different factors (new dirt, etc.) The only real way to test is a legit soil test or something like the jar test.

https://hgic.clemson.edu/factsheet/soil-texture-analysis-the-jar-test/

:cheers:

I know this is opinion based only, but would you think leaving on Sand then, then changing Available Water to 0.10 makes the most sense or would you recommend a different approach & Available Water amount?

I will try to eventually run the soil tests as you linked once I am able to get some more free time.

You could certainly have imported top soil if sand is all there is. Sand is extremely adverse to growing since it doesn’t hold on to water at all (thus the low AWC values you saw).

Perhaps start at 0.10 in/in for AWC— it’s a good middle ground. If you change the AWC, it doesn’t matter what soil type you choose. The soil type changes the AWC setting. Observe and adjust by small increments as necessary.