Fruitnut: Did you try cottonseed meal?
I was reading through a thread that you started in April of 2011 ("One and 7 yr blueberry growth with pictures"), and I saw that you mentioned that you were going to try cottonseed meal as a nitrogen source for your blueberries and other potted fruits. Did you try it? If so, were you happy with the results?
Here is a link that might be useful: One and 7 yr blueberry growth with pictures