I read the article-very imformative. But if soil is pretty deficient, and have 3 five year old trees, is there a good general apple fertilizer?

I wish I could give you a simple, definitive answer Jim. There are a number of different fertilizers + those found at the retail stores and that's a good thing; on the other hand, it is certainly best to know as much as possible about you soil and how your trees have been doing to even begin to do anything about your soil's fertility requirements.

Your state's extension service should be a place to start finding information about your soil, they are not likely to be the be all end all in that but could be very helpful.

Pay lot's of attention to your trees year round. The old expression, "The best manure for the field is the master's eye and foot." is pretty true. Just as a simple start on observations that you could do this time of year, go out and measure many of the shoots that grew last year to get an average of each of your varieties and record that for future reference.

Soil fertility is a science, don't let that discourage you from learning, just plow right in and learn what you can, it's what I still do.

I have been hearing good things about Azomite for providing a lot of trace minerals....would be curious to hear of anyone's experience with it.