There is something that you can add to that diet that will keep him normal. Its called Grassland tortoise pellets
I am adding this to my herbivore salad (uro, chuckwallas, collared lizards and beardies) and all of them are doing great. Captive chucks frequently have runny stools from too much water in their diets, and this really firmed everything up for them. I think that uros also probably get too much water content in a diet based on store bought greens. I grind the pellets up in a coffee grinder, then sprinkle it on the salad, about 1/2 to a cup per 4-6 cups of salad, then refrigerate the salad overnight. That moistens the pellet flakes. It is loaded with great stuff, including high fiber that herbivores really need, and lots of grasses and edible weeds that are on just about every herbivore reptile food list.
Another thing that you can add is this: