I’ve got bluegrass laid over Altvan-Satanta loam, which USGS describes as having an AW of 0.16.
I have two overlapping zones both set like this:
- Root Depth = 4in
- AW = 0.14 (sod loam on top of the native soil probably has a bit lower capacity
- Mild slope
- Soil type = Clay Loam
- Kc = 0.50 (spring), 0.55 (summer)
I cross-check Rachio’s estimates of ET against my local water authority, which has daily models of ET based on a test site a mile from my house. My Kc settings give good ET correlation between Rachio and my local water authority.
Rachio estimates it deposits about 0.33in per watering, less than 50% of estimated capacity. It does long cycle soaks. I’ve checked with catchcans, and if anything it applies less than 0.33in. The cycle ends long before dawn (drip & garden run after lawn).
Despite all of this, in the morning after watering, I can see signs of runoff and the lawn squelches a bit underfoot as I walk around.
Anyone have any thoughts on what could be going on?
AW could be too high. But it seems like only sand and high quality loams have AW of 0.12 or less. Regardless, I could revise this down.
Catchcans could be lying to me, I could need to retest
There could be something strange with the two zones. I’ve generally treated them separately, but that could be the wrong thing to do? This would probably be tackled by increasing the precipitation rate- but could screw up the areas that don’t overlap.
My soil does seem to absorb water quite slowly. It could be that the native soil below the grass is extremely slow to soak up water- but could it be so slow that hours later, it still hasn’t soaked up? This would be fixed by revising my root depth shallower.
The main other observation I would make is that while my settings are fairly aggressively tilted towards saving water (I push AD, ET, etc) the lawn still tends to look pretty plush & grow vigorously. Rachio seems to water before the lawn seems dry, and before the blades are folding. Which makes me second & third-guess my catchcans, and wonder about my ET.
Tricks to help rule out variables would be helpful. Unfortunately, some kind of probe to profile soil moisture content over the day, and before & after watering, is probably exotic & expensive