Things that make me go, "Hmmmmmm". Using 10-20-10 fertilizer, then topping with more phosphate doesn't seem to make a lot of sense. I'm not a big fan of fresh cow manure either. Every time I've used it, I end up with tons of toadstools in my garden.
My raised beds are filled with slightly aged horse manure, and some local organic matter. When I plant my tomato's, I wait until the plant is approx. 4 inches tall. I trim all the leaves off except the crown. I dig a hole that is slightly deeper than the plant is tall. In the bottom of the hole, I place a hand full of 3% phosphate (not Super Phosphate or Triple Super Phosphate), a couple handfuls of dirt and mix them, then I put the plant over that and cover it up to the crown.
This technique works great for me, but then again, I don't have sandy or clay soil. I have Texas Hill Country caliche which is high pH. I am going to try ammonium sulphate on other area's of the property though.
I don’t garden and I don’t know anything about the fertilizer, all I know is Mr. Nelson, who is a neighbor of ours, is a wizard at growing tomatoes. The best I’ve ever seen.
All I did was post the formula he publishes for growing tomatoes. :)
Good luck with your gardening.