
The concept of adding something to a dogs diet to prevent grass burn is based around altering the acidity of the urine, I have no idea whether Bicarb would achieve this, however by altering the acidity you run the risk of the dog developing kidney or bladder stones, a very painful condition, that would require expensive surgery so all in all it is better to either attempt to apply water to the lawn wherever the dog pees or just put up with the patches.