Decide how far apart you will plant our trees, keeping in mind that in some far away distant future, they will create a shade canopy of fifty feet or more. The 'nut gurus' have determined that pecan trees must have sufficient sunlight to produce optimally. Thus, while a distance of thirty feet was once recommended, we are now told we should plant between fifty and eighty feet apart. I personally would plant forty feet apart which will give you 24 trees per acre
The physical layout begins with yards, if not miles of rope or twine stretched the complete distance of your intended orchard. With an auger and a measuring tape, begin 'plugging' holes in the earth every forty feet (or whatever you choose.) I suggest you drill all the holes for your trees before you begin planting keeping a distance of at least four feet from any underground irrigation lines. Below are two diagrams for orchard planting. Our orchard is planted using the triangle design, which I personally prefer and it allows an additional 15% more trees per acre than the square design.
All you have left to do is plant your trees. Sounds simple, huh? The details involved in planting a pecan orchard are too complex to address on this one page. If you are seriously considering such a task, I encourage you to visit with area pecan producers and ask for their advice and input.
I will close with this thought...planting and maintaining a pecan orchard is like investing in the stock market. You have to be in it for the long haul. You have to be able to invest for years without seeing a return. You have to really want to be a pecan farmer, that's it in a nutshell.