Clay based new (not used) non-clumping kitty litter might help with the sand.Not so much the early rain, what I should have mentioned is that we have a lot of sand that really eats up any amendments ( leaf mold, cow poopy ect.) added to the soil so a lot of leeching.

How To Use Kitty Litter To Help Your Plants Thrive - House Digest
Gardeners and plant lovers are always looking for ways to improve their soil. Can adding kitty litter to your soil mix be the solution you've been seeking?
