I don't believe that the presence of turkeys on the place is in any way keeping us from having quail. There are large areas 100 miles to the south where both are doing well on the same properties.
In your case, and in many hundreds for thousands of acres of the Southland, it is the planted pines. Loblolly pine plantations are a death knell for quail. Think about it. What is there to hold or sustain quail? No cover, no food, no nesting habitat. I don't blame them for leaving. Really, it's not just quail. It's most other wildlife as well. The only species I have ever seen that do well in pine plantations are fox squirrels. And, my grandchildren would have to be starving for me to shoot a fox squirrel.
SRH
Stan, you are absolutely right about most loblolly plantations. The paper company land is good habitat only for the first few years after planting, and the way most of them manage their land it is not decent quail habitat again until it's cut.
But there is a management system here that produces good quail habitat by cutting way back on the number of trees per acre after they are mature. With 15-20 trees per acre, there is lots of room for an understory that is loaded with quail food. Longleaf is a better tree for this type system, but many of the folks that have these type plantations already had a loblolly forest, so they have made quail woods using them. It requires frequent burning no matter the pine species.
I have a friend who is a forester that makes his living managing these type quail plantations. And they are loaded with turkeys too.