FarmVille limited fertilizing and feeding
Currently there is a limited amount of farms that you can fertilize and feed. Even if you have not visited a particular neighbor's farm today, you may be unable to fertilize or feed.
Even though fertilizing can take a long time, it's a good way to earn XP because fertilized crops yield XP for you and your neighbors. Feeding chickens will also yield XP and possible Mystery Eggs.
This seems to be a temporary problem, as Zynga has not made an announcement regarding reduced fertilizing ability. There seemed to be a connection between not being able to access your farm and fertilizing/feeding. So let's hope Zynga gets this fixed soon.
Are you experiencing limited fertilizing ability?