|Ridding mower is optional.|
So four years ago my Dad and I had a cook off. He cooked one in his fryer while I roasted one in a pit in his back yard. I won hands down. Mine was juicier more flavorful and produced a more tender meat. His was noticeably more greasy, a factor of the deep frying.
So here is the process.
Start with a pretty decent hole. In warmer climates you can probably get away with going down about 3 feet but I would recommend deeper, at least 4 feet. You also want the hole to have at least 1-2 feet of clearance around what ever you are cooking. That allows room for a deep bed of coals to get the roasting done. *Disclaimer here that this year I moved to Utah and using a 3 foot deep hole was not nearly enough. We lost heat too fast due to the cold weather for much cooking to happen. I had to finish the turkey in the oven.
After the hole if dug the most ideal situation would be to line the hole with rocks or bricks. Keep in mind that you are going to be filling this back in so spending money on rocks or bricks is probably not an investment most people are going to want to make. The rocks retain heat better than just dirt and make the roasting a little easier.
This is a long process. Every time I have done this I have had time to dig the hole the day before and the whole afternoon the day of to devote to this process. Don't plan on doing this last minute or without at least a full day before to prepare.
Start a fire early. You need to accomplish two things first thoroughly heat the ground around the hole and second develop a deep bed of coals at least twice the size of what you are cooking. The times that I have been the most successful I have burned a fire starting at 2:00-3:00 and not put turkeys in the ground until 7:00-8:00.
Now you want to prepare your turkey. Season it however you like. I like an untraditional citrus, rosemary and garlic sauce that I place between the skin and the breast. It is important that you have time to bury the turkey before it starts to burn. The way you do that is to wrap it in several layers of aluminum foil and a couple layers of burlap.
The foil is key. You want to make a tight seal around the turkey so no juices/seasoning get out and no dirt gets in. Things are going to get bounced around a bit so having 4-5 layers of foil all over the turkey keeps things from getting to banged up. We also put a long piece of wire around the whole bundle so we have something to pull it out with.
Bury it! Get at least 3 feet of soil on top of the turkey. If you are expecting a freeze or rain over night putting a tarp on top of 3 feet of soil with another couple inches of soil on top of the tarp will trap warm air better and help keep heat in the hole.
Give it time. Plan on at least 12 hours of cooking time. Slow and low that is what this is all about. When this turkey is done you should be able to remove every bit of meat without picking up a knife. The best turkey I have done I literally slid my fingers in behind the breast and removed it whole. Another thing that is sometimes missed is letting the turkey sit after you pull it out. The idea is that you don't want a puff of steam when you cut into the foil, that is moisture leaving your meat, bad bad bad. Leave it sitting on your counter, in the foil until you can comfortably hold your bare hand on the turkey. This locks in all those juices and puts it over the top.
Best of luck! Comment with questions or feedback I have done it a few times now so hopefully I can help.