I have nine afghan pines that we planted to use as a windbreak/shade in fall 2006.

When they were planted, my father-in-law dug the holes and he made them exactly the same size as the 15-gallon buckets the trees came in. (I think he was used to working with relatively soft soil.) We don't have real caliche, but the soil was compacted when the house was built and it is difficult to dig, especially when it's dry.

One of the trees was heavily damaged by rabbits and died, so we had to replace it. I insisted my hubby dig the hole about twice the size of the 15-gallon bucket. That particular tree is doing really well. Although it was planted 6 months after the rest, started out the same size, it is now about 3 feet taller than the rest.

Is there anything I can do now with the other eight trees to loosen up the soil around them without causing harm?

They're all on drip.

thanks.

I did something similar to what you've suggested in irrigating a honey locust that I thought was a goner and it worked (no gypsum). It was a stick with a few leaves on it for the first 18 months and suddenly this year, it's a little tree. The difference with the pines is that they're a lot bigger, healthy looking (though stunted) and more expensive than the locust.

Thanks so much for your help.

Just spread the gypsum liberally on the ground around the trees, and water it in thoroughly. It's slow-acting.

And the advice to move the drip lines out is absolutely correct ... you want the roots to have a reason to leave that "flowerpot" they are planted in.