Available Water Capacity Verification


#1

Hello all, have many of you messed with this setting? I have looked up my soil database using some of the links provided in the app help section. It says Ramona Sandy Loam. Fair enough. But the default AWC (available water capacity) 0.17 inches.

But according to the website data base (https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm) the AWC for my house is 0.11 cm/cm.

Now, I am no genius, but I know that there is a units issue between 0.17 inches and 0.11 cm/cm. Am I not comparing apples to apples here?

Just curious to see if anyone else has ventured into this level of nerdiness. Thanks for your help, and have a great day!

Matt


#2

Check out this post. It could be the depth range that could be making a difference. And yes, @azdavidr and several others have gotten into this level of nerdiness. Rachio has a way of doing that to people!!! :wink:


#3

Regardless of how good or bad you might think the Rachio calculations are, it makes sense to test the moisture of the soil in most areas by sampling a small core of soil right after a watering and right before a watering.

This will be the best indication that the water is getting to the correct depth, and also that is it not too dry prior to the start of the next watering.

A simple soil sampler can be purchased OR made from a piece of 1/2" angle iron with a 90 degree bend 24" from the tip. Push it into the soil, twist, and when you remove, the soil will be stuck in the acute angle of the angle iron. It is also easier to remove this soil for the next core test than it is to remove the soil from several commercially available soil core tools.