It also depends on the type of grass you have. You can make an area of the yard that is a pee area, having an upright post might be tempting for him, and train him to only use that area. There are things that you can add to his water that are said to make the urine less acidic, but I wouldn't take the chance, Joey's more important to me than the grass. You can also try watering the grass immediately after he pees, or use pee pads.
