[felixworks]

-Topic

Chemical stump removal products use potassium nitrate as their main ingredient.  You drill holes into the stump, and then pour it in.  This accelerates the process of rotting.  I cannot find any literature or discussion beyond this.  So why does it work?  Does the potassium nitrate itself decompose the tree or does it enable fungi or bacteria?

[Arkcon]

That's what I'd heard, that soil organisms will grow better with a source of fixed nitrogen.  The nutrients also encourage plants to root there, and those roots force the wood apart.  It does seem to me that stumps treated with potassium nitrate do rot faster than otherwise.  But, the real reason potassium nitrate was used is different however -- years ago, you saturated the stump with nitrates,  then saturated it with kerosene, then lit it.  The nitrates provided oxygen for the buried kerosine and wood to burn.  Most labels don't suggest this step any more.

[felixworks]

I had heard of the burning step as well, but the reasoning provided for adding nitrate in that situation was to make the wood more porous, thus allowing it to better soak up the kerosene.  Yours sounds more plausible though.  Anyway, I also heard that the potassium nitrate seeps into the ground through the roots of the stump, and that the ground will then be oversaturated and unsuitable for plant life for a few years, even once the stump has rotted.  Perhaps that effect is just due to the process of the wood still rotting though.