Hi,
I have a few sulcata and they live in my fortified yard, in one 15' X 10' area I planted the seed you mention in the prev. post. My sulcatas spend some time there each day munching on the weeds that the seeds grow, however each turtle has its own personal tastes and favorites. I suspect when offered large amounts of various foods they just do what we would do if we lived in a "land of chocolates" and just go here and there taking a bite of anything that looks or smells good. Three of the four can't get enough hibiscus flowers and leaves from a 20 foot long row of hibiscus shrubs, the other one just turns up his nose at that plant all together.
I have five theories:
Theory #1 - In the wild I suspect plants are in such short supply that they simply stroll over to any green area they find and take a bite, if it doesn't taste like poison they keep eating.. This is just a guess, I've never seen anything on their natural diet beyond "mostly grasses". In captive situations we provide them with more food then they really know what to do with so they just eat what they like.
Theory #2 - Perhaps in the wild they do have times when a wide variety of vegetation us available to them, in this case nature has set them up to graze "here and there" to avoid completely destroying the food in one location, they eat a little and move on so it can grow back for the next pass by.. of course this is not a conscious decision by the animal, just an instinct to eat a little of this and a little of that. I've never seen my animals eat a plant to the point it was totally destroyed, although they always have a limitless supply.
Theory #3 - None of these theories are correct.
Theory #4 - Both of these theories are correct.
Theory #5 - One is correct and the other is not.
If you want the animal to feed on something it doesn't really "like" you may be able to mix it into a food they do readily eat and over time change the ratio of foods so they are getting a higher % of what you want to switch them to.. keep on it until eventually they will eat it by itself. This works with snakes and lizards, might work with sulcatas.
My two cents.
--jeff