yah, unless you have some unique soil situation, you should have deep sand (~neutral ph) in boynton beach. So, the manganese deficiency would presumably be from an alkaline water source.
I completely nixed (mulched over) about 90% of my grass and turned off all irrigation (both to the chagrin of the homeowner's association :-). The little patch of grass in the front yard starts looking brown during the spring, but my mangoes are happy, and that's all that counts ;-).