I have a friend that has a large grapefruit tree in his classroom. I mentioned to him in the spring that it was starting to look pretty tough, dropping leaves and just looking generally sad. He asked what he could do for it. I said the first thing would be to get it outside for the summer, at least. That wasn't really a possibility at that time, so it stayed in the classroom. This fall one of the other teachers pruned it back pretty good, it looks better, but still yellowing leaves and dropping them, but not as bad, probably because there aren't as many leaves left. LOL I told him that the school/classroom was MUCH too dry an environment for it and that possibly misting it every day would help. It is in a large pot; there is water in the pot saucer, the top is dry, and the water just sets. He does do the watering from the top. So, obviously there IS a drain hole in the pot, but it is not sucking up the water that drains down through. So, my question here is "can this tree be taken out of the pot, root pruned, and re-potted back in the same pot, since there has been some pruning of the top part of the tree?"
Grapefruit tree
Citrus trees of all sorts will grow out here where we have next to no humidity all summer so I think there's more to it than just a humidity problem. I'd suspect either it's not being watered properly, or it needs to be repotted, or it's not being fertilized correctly (or some combination of those three) Since you mention that the water just sits in the bottom and doesn't get absorbed back up, I would definitely check out overwatering as a prime suspect.
but the top dirt is bone dry.
How much sun is it getting? Over a prolonged period of not enough sun it would dwindle to nothing like any plant that required tons of sun.
East window............the ONLY window in that room (it's the band room). There are some things that cannot be changed. Don't think the school board would go for making a window where there is no place for one for a plant. LOL
I wouldn't suggest a window be put in, just that you can't force a plant to do well over time in a situation where it can't. A grapefruit tree needs a lot of sun and I would bet that's the reason for the decline.
Sitting in a pot of water is bad for any plant.
Just because the top of the soil is bone dry doesn't mean that farther down where the plant's roots actually are isn't still soaking wet. The best thing to do is stick your finger down a few inches into the pot and see how it feels farther down. Especially if the plant's been in that pot for a while it's probably got roots all the way down to the bottom of the pot, and it could be an absolute swamp down near the bottom if it's constantly sitting in a tray of water. The fact that it's not absorbing up any of the water from the tray it's sitting in tells me that the soil at the bottom of the pot is completely saturated with water, otherwise it should wick up. So overwatering is still high on my list of suspects (although not getting enough light certainly wouldn't be good for it either--it could be a combination of a few different problems that will all need to be addressed before the plant can be healthy)
He told me that over Thanksgiving break he would probably try and pull it out of the pot and see just what he is dealing with. I think his time element frame is pretty tight right now. So, I will pass these nuggets on to him. Thank you for your input, everyone. :>)