Question
I have a tree in a large wooden potting container, approx 2ft in diameter, & it's leaves are starting to turn brown because when I water it the water just runs right thru. Can I replace the top half of the soil with new soil & cure this problem? It is too large to take completely out.   Also is there a way I can recondition this soil & use it in my flower beds once I take it out.

Thanks,

Debbi

Answer
Hi Debbie,  Roots are at the soil surface for a reason.  They need air.  If you cover these you plant may die.  The soil that needs to be removed is at the bottom of the plant.
If you can't get someone to help you properly repot it, get the longest screwdriver you can find.  Push it down through the soil and open up a couple of dozen holes.  Fill these with a potting soil that has a water holding polymer added to it or you can buy the polymer from your local garden center and add a very, very tiny amount in the holes and cover with fresh potting soil.  The polymer looks like sand but swells when water is added and will help your plant keep from drying so quickly.  
If you can repot it, throw away the old soil, don't reuse it.  Jim