A fertilizer that has blood meal (free from the butchers), bone meal (from the same place) and wood ashes (Winter time abundance!) in a ratio of 2-1-4 respectively is similar to a 10-10-10 fertilizer. That's what I use on most my plants.

Bump the bone meal and wood ashes up to 2 and 5 and you'll probably have what you need.

My fiancee and I make a tea, which not only does a much better job than anything you can buy, but is much cheaper. You can adjust the concentration, allowing less distribution.

We make a concoction of worm castings, Mycorrhizae, organic fertilizer, and a small amount of lime. Put in large vat (5 gallong bucket or bigger), and put an air tube into it (like the ones for fish tank), which blows a lot of air into the bucket. Let this sit for a couple of days, and bam, you've got some good stuff! It has worked for every single thing we've ever tried it on - plants, bushes, flowers, trees, etc. They love it. The longer it sits, the better it is.

In your case, with so many trees, I would just break them into smaller groups of maybe 10, and water one group a week. So every 5 weeks, you are starting over again with the first group. You don't even have to do it that much.

Enjoy

Here is a link that might be useful: Mycorrhizae Information

Suggestions above are good. I would say if you would provide good organic material for the soil, the trees will take what they need and leave the rest, so you don't have to worry about the numbers. Lots of compost, slightly aged horse or almost any manure, leaf mold, wood ashes, coffee grounds, whatever you can get, pile it up around the trees, at least a few inches away from the trunks. And you can get all that stuff free.

If you just pile wood chips up in a pile for a few years they will make some nice organic material, although it helps if they are mixed with other things like grass clippings. Can you make a deal with some lawn services and landscaping companies to bring you the grass, leaves, weeds, etc. for you to use as mulch/compost for your trees? In the winter I sure wish I knew somebody who wanted the ashes from our wood stove. Some times of the year I spread them in my own orchard, but I don't like doing that in a foot of snow!

Really, don't worry about those numbers, plants don't know numbers at all. When the fertilizer is organic and slow release like compost they take whatever they need and are very happy with it.

Marcia