Where did all the Soil Moisture Go?


Soil Moisture dropping too fast! Where did 24% Soil Moisture go?

We’ve been absolutely drowning down in here in the South East with daily Pop Up Thunderstorm rain. Correctly, my Soil Moisture readings on all of my Zones went to and stayed at 110%. My next watering is currently a week away (7/7). This morning we were overcast, will very little evaporation or wind, and we’re effectively in our 100% humidity portion of Summer. Anyway, the yard is sopping wet, and still has a noticeable softness to it. I would characterize my observed Soil Moisture level to be 105%+ still, yet Rachio is estimating 86%. There is no way that I’m below 100% SML at this point.


I would suggest that SML be calculated off of 110% of Previous Moisture Balance, not 100%. I am configured for 6" root depth because I have new sod. I started with a 4" depth, but figured I would give those roots reason to go deep and switched to 6" a week ago.

Is there any way to buffer the decline? it’s simply too aggressive.




Can’t say why but you can always do a “fill” until soil conditions are no longer over saturated.


Yeah, understood, but I’m not going to baby sit this thing and Fill zones every 3 days. That’s a lot of clicking since it’s adjusted at the Zone level.

I’m seeing that it’s calculating off of 100% of 5", but it should be calculating off of 110% to be a little more realistic. What I’m trying to say, I didn’t lose an whole inch of hydration today, as my soil is actually closer to 105%.

It appears that SML is calculated off of Root Depth - 1". Anyway, I still didn’t lose an inch of moisture.



We don’t usually recommend flex daily for sod but seems like it has worked this far. The easiet lever to move is zone crop coefficient if you feel soil moisture is going up or down too fast. I’d recommend moving in +/- 5-10% increments. More means burning moisture faster, less means burning moisture slower.



I don’t like it, but that’s what I had to do the month that we were getting rain every day. When it’s just a bit of rain for a day or two, the 110% saturation level works great, but I’ve found when I get rain day after day, my soil just doesn’t dry out as fast as the system thinks it’s going to. So I’ve had to do the fill route. The only problem with that is I was doing a fill during the day to make sure I’d get to 100%. Then it would rain in the early evening, but then the zone was stuck at 100% instead of 110%. Unfortunately for me, when this happened I was just getting ready to travel, and I had to guess at things for a few days.


Yeah. Once water exceeds the pore space of soil, ET models break down because now you have to evaporate straight water and wait for it to infiltrate or run off. I imagine the model for that is a bit more complicated especially if moisture keeps getting added. I wouldn’t expect a sprinkler controller and the Cloud to figure that one out!


@Kubisuro Thanks for teaching me something new today! I’ll have @theflexdude start thinking about this, but yeah a difficult problem for sure. :wink:



This is exactly what I’m trying to describe. Once my yard goes > 95%, the models/equations are out the window. It simply takes 3 days of no added moisture to get back down to something more normal. Meaning whatever the variables are that reduce moisture, they are 1/3 their normal rate. Simply, we are different than West Texas.



And with Humidity near 1000%, that (evaporation) just ain’t happening!


I have noticed similar, where I have wondered how 100 percent or 80 percent could evaporate to 0 percent in one days time in my turf zones.


Sort of dealing with the same issue, getting .2 and .3 inch rains several days in a row, and needing to manually fill each Zone so that the soaked soil starts drying out before Flex daily can kick back in to start watering on the following hot sunny days.

An option to fill all zones would be a help, but you would want a good disclaimer to go with it so the user would know what they were doing.


Thanks for that insight, now I understand where I’ll need to intervene.