Water Depletion Questions


#1

This will be my first real season to use the Rachio. I got it towards the end of last season, so I really didn’t see how it worked. I’m in Alabama and have zoysia grass. I’ve researched my soil type (Sandy Loam) and have my settings as such: Available water 0.15, Root depth 9, Allowed depletion 20%, efficiency 80%, crop coefficient 65%.

I’m not sure why the Rachio set for my grass to water three days in a row (Wed, Thurs, Fri). We just had 3 inches of rain on Sat night/Sun morning. Temperature on Monday were in the high 50s, 70s on Tues and Wed, and low 60s on Thurs which is great for Alabama. It’s supposed to rain Saturday night. My grass doesn’t seem like it needs that much water for this time of the year.

Does Rachio Flex take into account actual temperature in evaporation? After any rain the max amount of soil moisture is 110%, is that a valid theory?

Any setting I should adjust to get it to not water as often?


#2

Your allowed deplition is way tooooooo low, 50% minimum for that turf.

Basically that setting tells flex that when 20% of the moisture in your soil transevaps away, reapply water to max awc.

110% is valid in my opinion, there was some debate about that a few years ago. In my opinion 110% is a super saturated point in the soil column, where water squishes through your toes when you walk on it, basically the maximum amount of water that the soil column can hold. A valid state but incredibly dangerous to the plant and soil if maintained for long periods of time. So 100% represents the optimal state of moisture…

Yes it does, but I feel it could be a touch better, my settings are ideal for my peak heat, I feel during the spring the te rate is a touch high for the temps. In spring I’ll go 6-9 days between waterings and 4-5 days in summer (Georgia).


#3

Made me look up crop coefficients for turf. Naturally UC Extension came through:


#4

Makes sense. Reset my minimum to 50%. Thanks!
What should I set this duration to (how many inches should duration put out per run)?


#5

With flex daily, you shouldn’t need to touch the duration. It calculates it for you based on all the settings you put in.


#6

the duration will be determined by the zone efficiency, root depth, awc and the pr.

i would say your root depth is reasonable for st. augustine, probably ok for bermuda if you are in sandy soil (but probably not with that awc).

im assuming you have used to soil database to reach your available water capacity. (http://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx)

the wild card here is the pr of your heads. i think this gets overlooked or ppl take a wild guess. the best way to determine this is conducting a catch cup test. if you want to spit ball it, you can look up your heads on the manufacture’s site and get an idea, but you will need to know your water pressure. if you like to live dangerously, take the middle of the road in water pressure.

once you get the pr set correctly, the flex schedule will compute the duration of your schedule, its really nice, everything i have runs on flex.

please feel free to ask more specific questions about any of this, its hard stuff but in my opinion worth it.