Behnam,



 



Sorry I did not explain well enough.  The ITHRL parameter is based on soil water as a percentage of total available water capacity between the upper and lower limits within the irrigation management depth.  When the soil water contents reach this threshold, irrigations are triggered.  Within the irrigation management depth, % soil water is calculated as



 



%Soil Water = (Actual Water – Lower Limit)/(Drain upper limit – Lower Limit)



 



where the actual water, drained upper limit, and lower limit are depths (units of mm).



 



I was saying not to confuse this with %Depletion, which would be calculated as



 



%Soil Water Depletion = (Drained upper limit – Actual Water) / (Drained upper limit – Lower Limit)



 



The ITHRL parameter for triggering automatic irrigations is based on the % Soil Water equation, not %Soil Water Depletion.



 



Let me know if you have any more questions.



 



Kelly



 



 



 



From: Behnam Ababaei [mailto:[log in to unmask]] 

Sent: Tuesday, August 31, 2010 4:20 AM

To: Thorp, Kelly

Subject: Re: Why Management Depth Instead of Rooting Depth?



 



Dear Kelly,

I will test it. But before it, consider that the default value is 50% and it is more than FC values in almost every soil textures.



Thanks again for your guidance.



Best

Behnam