Natural processes and/or your actual fertilizer treatments.
Just because people have been saying the same stupid falsehood for 80+ years doesn't make it true.
If you would like to learn why it is a stupid thing to say, I suggest starting by reading this
DTIC (Natick) report on the conversion of nitrocellulose into usable fertilizer.
It isn't just a bland chemical formula, or list of toxicities, or summary of leachates, like most references. It provides an overview of why nitrocellulose is not a fertilizer and how hard we have to work to break the nitrogen out to make it useful.
And, yes, this report is from 1976. We have known for a very long time that nitrocellulose is not a fertilizer.
I'll share one notable sentence from this report, which sums up the entire reason for the study and the reason why nitrocellulose is
not a fertilizer:
Since nitrocellulose contains 12% to 14% nitrogen it was suggested that this material might make a good fertilizer, if the nitrogen could be converted to a usable form.
Emphasis mine.
And
from the patent that this report seems to have been based on:
Although the process of the invention may be carried out with any nitrocellulose, it is particularly applicable to nitrocelluloses having from about 2½ to 3 nitrate groups per glucose unit in the nitrocellulose chain since these nitrocelluloses are the types commonly produced commercially and they are non-biodegradable.
Emphasis mine.
Further reading is not difficult to find via your preferred internet search engine; and there are additional discussions on this forum.
If you want to keep your head buried in the sand, go for it. But stop perpetuating fuddlore.
