weirdly, the devs are reluctant to consider it a bug, it doesn't seem to be added on the trello board they use to track bugs (https://trello.com/b/rldv58ho/anno1800-known-issues-list)
there was this comment on the discord channel:
Aestris — 11/04/2022
u/Ubi-Thorlof | Oliver Is there a chance that the fertilizer works will get adjusted?
Ubi-Thorlof | Oliver — 11/04/2022
potentially, we'll discuss some balancing feedback this week or the next
I refuse to believe its not meant to have been 1 minute or even 30 seconds to produce one fertilizer. Not because its how powerful I want it to be, but simply because thats how powerful one should expect it to be considering how the fuel station and grain silos work. like, its 1 oil spring/oil refinery/rail network/oil tradeport/fuel station for 20 farms, 1 grain/corn/teff farm for 5 animal farms and then.... 1 fertilizer works plus animal fars in range for 1 crop farm... doesn't make sense.