Using Web Soil Survey to define your soil settings


It has taken me awhile to master the USDA soil survey web site. I use it as preliminary information in designing septic systems. Our soil in the county varies from pretty good clay loam to sandy soil on top of caliche (calcium corbonate) to pretty hard caliche rock (limestone rock).


@Sdennis I had the same issues- it’s not incredibly intuitive on how to use the site! I think have a feeling that’s part of why these instructions have been so helpful and popular…


Hi @franz

Is this now in the software? Is that how my Gen 2 Controller determined a 0.2AW setting?



I also have flower beds that we brought in soil and built them up. How would you determine AW in these situations? My mason jar test came out Loam with 45% Sand, 40% Silt and 15% Clay. Currently AW set at 0.2 like my grass zones and agrees with USDA Soil tables.


@tomlay I usually go with loam for nice, store bought soil. Loam’s AW is 0.17, so I may adjust your flower beds to that. Web soil survey is not incorporated in the software, however we have the average AW value for each soil type pre-populated in each soil type, so if you selected the correct soil type the AW should default to pretty close!



I did find a very interesting link that helped.
And yes my bedding soil did test out using the Mason Jar test as Loam. In looking at the above chart I did notice that AWC increased with OM (organic material). Since we include additional organic material in the beds I used the the higher 0.2 AW value as recommended by the chart.



@tomlay I think that’s a good call upping it a bit! I like that chart, thank you for sharing!


@azdavidr - Thanks for this. Not sure how I missed it after having my Rachio for a while now, but glad I found it. Excellent work.


David this is an amazing guide and made a confusing government site with great soil information easy to navigate. Answered a lot of my questions as a new Rachio user. Turns out I have “very gravely loam” <3" and “very gravely clay” 3" to 20" with an AOI of 0.07 in Fountain Hills, AZ. We do dig with a pick-axe here. All sounds about right.

Also great meeting you at the Phoenix SRP training session.


Hey @Trebacz, I’m really glad that you found the guide useful, and it was nice to meet you as well. Thanks for the nice comments about the guide! Welcome to the user community. Be sure to post with any issues you might be having, and/or any successes as well!


Just came in to say thank you for this guide! Very helpful, and Rachio should either create their own or create an official play by play like you did to help people navigate the site and find their soil type.


Thanks @Skyball, I appreciate you taking the time to post this!


@Skyball @azdavidr @Trebacz

I’m having our amazing technical writer take this and make it officially documented on our site. :wink:



Thank you for posting this. This forum is very helpful, which is one of the reasons I recently install a Rachio v3. My run times are 43 minutes per station (flex daily), where they were 20 minutes per station three times a week with my prior non-Rachio controller.

I’ve used these instructions to find my soil quality, which I thought was clay loam. It turns out that I have the following:

Ap - 0 to 6 inches: silty clay loam
Bw - 6 to 15 inches: silt loam
Bk - 15 to 28 inches: silt loam
C - 28 to 80 inches: silt loam

What should I enter into the app?

Also, is a slope of 0-16% considered a slight or moderate slope?



Welcome to the community! In addition to what you posted you should also have an ‘available water’ number. The description of what you should enter into the app. is in steps 16-19.


This affects the cycle/soak times. I’d start with slight, if you experience any runoff move to moderate.



Thank you. My available water is 0.2 per the websoil survey. This was the default entered by Rachio, so I didn’t make any adjustments.


@Noonan I’d recommend starting with a zone or two if you are doing flex daily. See how it performs, get it dialed in, ask the community if you have any questions, then roll out to other zones if you enjoy the dynamism of it.



Franz, I live in Castle Rock so just down the road and for my shrubs after using David’s spreadsheet the shrubs are with all the near default settings are running every 5 days. I am not sure that is enough as some grasses are now getting distressed, so just checking on how to increase frequency? I changed root depth from 15 inches to 8 inches as the shrubs are only 2 years in…thoughts?


Your decrease in root depth will lead to shorter, more frequent irrigation. Maybe that’s enough? If not, and you’d like to increase the frequency further then consider increasing the crop coefficient, maybe 5-10% for starters.