I made dirt rings that were about 1' larger in dia than the drip line of the canopy on the trees that I planted. About a 6" high dirt ring. I filled up the ring with water 2x a week (or more if hot and dry) and just let it naturally seep down into the ground. I also hit the inside of the rings with roundup to keep any grass or weeds from competing with the trees. Worked great.

Like Rainman suggested, I'm installing a drip system this year and will put it on a timer.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).