Besides, why the heck do you allow animals if you aren't willing to put up with the results of your decision? Charge a fee for animals and pay somebody to come around and clean up the poop, there are services that do that very thing.
Dog poop on the lawn is a result of dogs and not picking up the poop. If the poop is cleaned any less often than continuously; people will step in, fall in, and roll through (with a wheel chair) dog poop. Owners should pick up dog poop from common spaces.