Here's another fun fact about Potassium Chloride. It is a naturally occurring salt which is found in easy to get a deposits in many areas. So it is the cheapest source of potassium available. Just grind it up and apply it as fertilizer. That's why most fertilizers use it. But potassium chloride is unstable and decays naturally releasing Radon gas, much like Granite does. I'm sure you have heard tobacco contains radioactive Radon. That's not true. First off, although Radon is radioactive, it is an inert gas and won't bind to any other elements to form a chemical compound. So it is worthless to plants and they won't take it in. And it has a half life of only 8 days anyway.
What does happen is that Radon decays into Polonium 210 after 8 days, which is a metal with a half life of 80ish days. (going from memory here) Then that decays to a radioactive isotope of Bismuth. Eventually it decays to a stable form of Bismuth or Lead. Tobacco leaves are very sticky, so after the Radon has decayed into Polonium 210, those teeny tiny particles of metal floating in the air can and do stick to the leaves. Usually the under sides. So your tobacco can contain Polonium 210 (nasty stuff for your cells to be near) or unstable Bismuth, depending on how long it has aged and what stage of decay the elements are at.
If you live in an area with very little on no naturally occurring Radon seeping up out of the ground and do not use Potassium Chloride fertilizers, your tobacco will not contain any radioactive elements. Some of you old codgers like me might remember our old surgeon general C. Evert Coop from back around 1990. (the guy with the billy goat beard) He was on 60 minutes back then and said if were were to ban the use of Potassium Chloride on tobacco it could reduce the lung cancer rate from smoking by 90% by getting rid of the radioactive components. But it is still allowed on tobacco because potassium is the most scarce of the essential elements and it is cheap to mine.
I'll end my late night rants here. Except to add that peat pots and pellets are on my S list and not my hit list. lol