Morton Kosher Salt (as well as most other store brands) is made by flattening salt granules into large thin flakes while Diamond Crystal uses a 100-year old proprietary evaporation process in which upside-down pyramids are stacked one over the next to form a crystal. Diamond Crystal's method results in a hollow pyramid-shaped grain. This hollow structure accounts for the salt’s lightness, & crush-ability. Because of the hollow pyramid's shape, each teaspoon of Diamond Crystal Salt has less salt than Morton Salt, thus you are less likely to over salt (you can always add more salt).
If you're not already using it, I recommend making a switch to Diamond Crystals, if only because it's much more forgiving in the kitchen. Also, most recipe writers don't specify which salt they use in their recipes, but I have a hunch since most chefs (at least that I know) use Diamond & most cook books are at least co-written with a chef, Diamond Crystal are being used in the recipes.
We use Diamond Crystal Kosher Salt in our kitchen, so if you're using Morton's simply reduce the measurement by 1/3. For example, 1 tsp Diamond Crystal = 2/3 tsp Morton Salt.
ADD SALT TO POULTRY BY EITHER BRINING OR SALTING
WHY IT WORKS
Salting Poultry is a great way to keep lean proteins juicy. When salt is added to the surface of poultry it draws the moisture out. The salt then dissolves in the juices forming a brine that is eventually reabsorbed. When the salt is reabsorbed it changes the structure of the cells making it more tender and allowing it to hold on to more of it's natural moisture by about 10%. Most unsalted meat will loose about 20% of it's moisture during cooking, so by adding the salt you basically cut the moisture loss by half. (Sorry I can't explain further than that — I wasn't that great of a chemistry student.) Salting does take more time, but it won't keep you from getting crispy skin when cooked, if desired.
Brining poultry works in pretty much the same way by changing the structure of the cell wall, tenderizing, and giving the cell the ability to retain moisture. The differences are brining is faster, & will add moisture to the meat, not just retain it, resulting in super juicy poultry. The downside is, with all the extra moisture, achieving a crispy skin becomes more difficult. Another complication to brining is space, as you need a container big enough & the fridge space to store the bird. I use a huge soup pot and have our fridge shelves situated so that it the pot fits. In the past I have also placed the birds and salt solution in a cooler with ice – just make sure to add ice as needed.
So, in short, if you want a pretty juicy bird with crispy skin, salt the poultry; but, if you want a super juicy bird and don't care about the skin, brine the bird.
Regardless, only salt or brine poultry that HASN'T been pre-basted, koshered, treated, or seasoned. It has already been salted.