You can teach him to potty in a certain area of the front yard. Having a "go potty" command is very helpful for this (well actually it's helpful at other times too). To do this you'll have to take him out on leash, take him to the designated area, and use your potty command. If he doesn't go right away you can basically just walk in a circle while repeating the potty command till he goes and generally be boring (reward when he potties). Keep in mind that exercise stimulates the bowels so taking him on a walk before letting him loose in the yard would be a great idea too.
Some caveats though. Many dogs won't potty in a "dirty" place so if you want to train him to use a small area you'll need to clean it up frequently (I'd say every couple of days at most, depending on the size of the area). Also, peeing in one spot frequently is very likely to kill your grass. One thing you can do to prevent this is pour water on the spot after the dog pees (it dilutes the nutrients in urine and will actually cause it to work like a fertilizer). Some people keep a watering can or the like in the yard for this. Don't use those tablets you can buy at the pet stores to prevent brown grass, messing with urine pH can be trouble.
Some caveats though. Many dogs won't potty in a "dirty" place so if you want to train him to use a small area you'll need to clean it up frequently (I'd say every couple of days at most, depending on the size of the area). Also, peeing in one spot frequently is very likely to kill your grass. One thing you can do to prevent this is pour water on the spot after the dog pees (it dilutes the nutrients in urine and will actually cause it to work like a fertilizer). Some people keep a watering can or the like in the yard for this. Don't use those tablets you can buy at the pet stores to prevent brown grass, messing with urine pH can be trouble.
