MAD not working properly


#1

I have managed allowed depletion set the 30% on all my zones. Last night I check led the moisture percent in the android app and all my zones were down to 14%. How is that possible if my mad is set to 30%? I think it’s seeing the 30% as acceptable moisture level not 70?


#2

MAD is used to determine irrigation amount (field capacity) applied to a zone to fill the bucket.

The equation used is

MAD * Root zone depth (RZD) * available water capacity (AWC - derived from soil type).

So, for my zone I have cool season grass (RZD = 6), MAD at default (50%), and soil type of clay loam (AWC = .2)

6 * .5 * .2 = .6 inches.

For my zone the Iro will track to .6 inches. Now, each day ET pulls this number down, and precip + irrigation pull it up.

When it hits zero we water.

MAD is used in the part of the equation which determines irrigation amount, which in turn is used for frequency and duration.

So, when MAD is set lower than 50%, let’s say 30%, my irrigation amount would be .36 inches.

It will now be quicker to reach zero, hence watering frequency is increased (more often), but my duration will go down since I only need to fill .36 inches versus .6 inches.

Hope this helps.

:cheers:


Exposure: Extreme Sun
Exposure: Extreme Sun
#3

Franz, so is my problem that their was forecasted rain that didn’t happen?


#4

Forecasted rain that never appeared could potentially defer your schedule one day. The next day we will correctly observe that there was no precip and pull the moisture level down accordingly. Trying to work on a correction where we use forecasted precip with a different weighting.

:cheers:


Adjusting Flex Schedule Depletion Level for Climate with Inconsistent Rain Forecast
#5

I would agree. It’s very common to have forecasted rain here daily that doesn’t happen. I would maybe weigh it 50% the value


Adjusting Flex Schedule Depletion Level for Climate with Inconsistent Rain Forecast
#6

@ghctim, just wanted to follow up on your original question. I believe the issue you’re seeing is that the 14% was the remaining moisture balance BEFORE you’d hit your allowed depletion. Therefore, using the numbers from Franz’s example, at 14% with 30% MAD, you’s still had .05 inches of the .36 inches before the Flex schedule would execute.

I hope this clears up any confusion between the moisture balance % and the allowed depletion %.

Best, Emil


#7

@emil yes! that is a HUGE help. Ok, now that makes sense! Hmm…but the graph doesn’t show that…