I just bought a house that has some borders that have been mulched with crushed shell. There is a row of italian cypress and some palmettos growing in it. Someone told me that the crushed shell makes the soil too alkaline which is already a problem here. I'm planning on raking as much of the shell away as I can and replacing it with wood chips. Should I add something to the soil to reduce the alkalinity? The cypress don't look too happy, lots of brown spots.