hand trowel ... dig 3 or 4.. 6 inch holes... AND FIND OUT IF THERE IS ANY MOISTURE AT DEPTH ...

when i run irrigation on trees... i run it 6 to 8 hours on my sand ... because that is what is required with my engineered system of x gallons per hour... taking into account my sand...

how did you come up with your number of hours???

and the way to find out.. is to dig the holes.. and discover how its working...

you dont say how large the transplants are ... but if they are over 6 feet... you need to have the entire root mass planted dampish ... but not sodden.. for up to 3 years ...

and it isnt surprising.. it appeared.. when the heat hit ...

it has absolutely nothing to do with fert ... and as far as i am concerned.. you NEVER fert trees ... especially if you fert your lawn ... the tree will get/steal all it ever needs ...

one might suggest that a soil test will tell you if anything is lacking.. i feel its much simpler to look around and see if trees... shrubs.. plants.. are thriving.. in general.. and if they are.. then the soil is good enough for your trees ...

pic is you want more info ...

ken

I didn't realize Red Sunset Acer rubrum was suitable for zone 9 in California...