Not from Texas, not a pecan expert...but maybe telling you what we do, with trees in general, will help.
Take a soil test, most labs will return a recommendation sheet for the specific crop.
It doesn't make sense to just throw down fertilizer with out knowing what is deficient. Too much of many nutrients is as harmful as too little, more harmful in some cases. It is also a watse of time and money to randomly dump fertilizer.
If soil pH is a problem, that too will need to be measured so the correct course of action can be made.
Here in south east WI our soils are very widely variable. One can rarely mix a batch of fertilizer and go hit several customers, and those that do, are probably not doing the best job.
Trees are not like grass, which wants one thing, nitrogen and lots of it.