A pound IS a pound, the world around. Heh.
A pound of black powder pressed into a brick will burn quite impressivly. A pound ground to a fine powder could... well, go BOOM. All about reaction rates and surface area.
In ground meat less cure is required because of the cure contacting practically ALL the meat surface at once, not requiring much time for the cure to take place, and therefore less time needed as well.
Curing chems degrade into nitrous oxide- this is actually what does the "curing". It it a reaction that happens over time when exposed to moisture and oxygen. First the nitrate will convert to nitrite, then to the No3 oxide.
Long cured products use more of the NITRATE form, because over time it continues to contribute nitrites and then No3 to the meat, allowing a long term curing process. Prague#2.
Shorter term uses more of the nitrite form. (Prague#1) And if the meat is ground, less of that form is required to complete the cure.
Also, this is mainly applicable to Morton's TQ, which has BOTH the nitrite and nitrate components. Therefore in the quicker curing thin cuts/ground meats, you want to decrease the nitrates, as they are just not needed.
When injecting whole muscle meats with cure, you must add the total amount of cure injected and subtract that from the dry you use for the exterior rub. And when injected, it's much safer for the large cuts because it's going to complete the cure quicker..avoiding "bone sour" and other bad things that could happen before the cure penetrates to the interior.
Also Morton's also recommends 1.5 teaspoons/Lb ground meat...