Tenants Wants to Put in Sod

[Ana Doxwin]

My tenants have been living a my rental property for over 4 years. When I first rented it out to them, the backyard was just dirt. They now want to put in sod for their kids. I think they may want to DIY this and pay out of their own pocket. I'm hesitant because (1) I don't want to bear the burden of having to maintain grass and irrigation after they leave and (2) I don't know how this DIY project may turn out and I may need to undo everything they did after they leave. The house is a part of an HOA, and there is a community park with rolling hills about a quarter mile away. Also, we're in Phoenix, Arizona, and I have some reservations about how ecologically responsible it'd to put sod down, during a time of drought and water scarcity. They'd only bounced this idea off of me recently, and I haven't given them a solid response. Could anyone advise me on this? Thank you.