Question
Residents walk their dogs all alongside our lawn and allow them to urinate - what can we put - spray on the grass to discourage them from doing so?

Answer
If I found a foolproof answer to your question, I would not be here, writing this. Seriously, you might consider posting a sign which can be as friendly or formal as you like. If you aspire to Sainthood, you might erect a "pooper scooper" station and keep it supplied with bags. None of this is guaranteed to work. I worked in a Cemetery where a repeat offender defiantly allowed his dog to desecrate memorials...until I surreptitiously photographed the offence and turned it over to the Police. I apologise for the apparent lightheartedness of my response. I really do empathize with your feeling of annoyance.