When your dog's pee is causing yellow grass he has overacidification.
That increases his risk for bladder stones and joint problems, it's often caused by food that contains corn, soy and/or glutein containing grains like wheat, oat or barley.
If your food contains one or several of these under first five to seven ingriedients you should change his/her food, don't ask your vet about food brands, lots of brands have contracts with vets and clinics so they just recommend brand XY no matter if it's really a quality food or not (when they don't and it gets mentioned, they have to pay fines about 100000 minimum), and earn extra money selling it to you.
Get urine test stripes from your local drugstore, hold it into the urine jet next pottie time and contact your vet about the results (but don't let he/she foist that urinary food by royal canin, hill's science diet or whatever on you).