I've seen no one mention this issue, so I'm going to assume I'm making a silly mistake:
I've recent acquired plantation management. With an iron hoe, I tended a few fields and noted that the upkeep did not reduce whatsoever and remained at 50%. I made certain that the tending action had completed on these fields and verified that the "tend" option no longer appeared when I clicked on them. These fields were in stage 1 of cotton. Uncertain if it makes a difference, but I had planted the crops before acquiring plantation management. I harvested one of the fields to see if it would magically reduce afterward, but this did not happen. If anyone has some guidance, I'd greatly appreciate it. Thanks!