Place salt (1 cup) and brown sugar (1 cup) in a saucepan and add 4 cups of water. Bring to a boil over medium heat and whisk until both salt and sugar are dissolved completely. Remove from heat and cool completely.
Rinse turkey (1 10-12 pounds) inside and out, remove and set aside neck, liver, and giblets. (Save for making gravy or another purpose).
Place the turkey in the container (see above for suggestions). Add completely cooled salt, sugar, and water to the container. Add oranges (2), lemons (2), and herb bundles (6 sprigs thyme + 3 sprigs rosemary + 6 sprigs parsley). Add 1.75 gallons of water to the container. (The total amount of liquid from the salt and sugar mixture plus the 1.75 gallons will equal 2 gallons)
If your turkey is larger than 10-12 pounds you will require more brine. Add 1/2 salt, and 1/2 packed brown sugar to 1 gallon of water needed to completely submerge your turkey. This of course will vary on the size of your turkey. I've never needed more than a total of 3 gallons of brine.
Soak the turkey in the brine, covered and refrigerated, for up to 24 hours.