- How can soil (clay loam) with a capacity of 0.20 in be 100% full at 0.6 in?
a. I suspect that root depth (6”) has something to do with it, like 6*.2*50%, but that would be 50% full at 6”?
- How can soil hold more than 100%? Isn’t that the definition of saturated? I feel that this is a weakness of the database. I think the system will place it in my gas tank and severely delay watering again.
- It appears that the moisture graph is expanded, confusing and to some degree wrong. There should be three lines: 1. 0%; 2. allowed depletion at the MAD level, and; 3. saturated field capacity. Instead of going from 50% to 100% as the default, it is expanded to 0% to 100% with the ability to go under 0% and over 100%. The present moisture level of the soil should always fall between the upper and lower lines. There should be a manual method to set the present level in that range beyond zero and saturated if one wants to correct things.
So 100% full really means 50% of the Max. Allowed Depletion (MAD).
FULL (MAD=50%) = 0.2 (in water)/(in soil) * 6 in soil * 0.50 = 0.6 in water
It can’t, and it would indicate roll-off. I don’t know the specifics of why 120% was chosen, but I know that there’s some amount of inaccuracy of what 100% is in the app. versus the reality of what’s happening in your lawn. I don’t know if that has anything to do with it, but I’m OK with it due to that reason.
I guess it’s a matter of opinion to a point. For me, if below 50% means I’m below the permanent wilting point, I don’t plan on seeing many data points there. I always like to see as much of my data on the screen as possible, so 50-100% works well for me.
I’m not sure I’m following. How would that be different from what’s under the adjust button ?
Thank you for the clarity on the MAD math. I would prefer that the range was left as an unaltered ratio from 0% to saturated at 100% with normal operation a range in between 25% to 75%, but so long as I know the math and the range, i can work with it. I was unaware of the 120% limit. I understand that there needs to be a hard limit at some point and that limit is above the wet irrigation point by some amount, so I guess i can see that.
" I’m not sure I’m following. How would that be different from what’s under the adjust button ?"
It would be a minor improvement, adding the ability to calibrate to a measured soil moisture level on a given day, rather than just saying it is wet or dry. Even a subjective squeeze test of a simple core sample could be done fairly well. I think this would be most useful for long roots (24") in the spring and fall when the interval is long (3-4 weeks).
I see what you’re getting at. You can increase your MAD level to see more than 50%, but then the system will let your moisture deplete to that level too, which is probably not what you’re looking for. At that point it requires a display tweak, which it sounds like was your original suggestion.