Most of what wood ash is is very water soluble so the problems that might create are fairly quickly washed out of that soil, although it does go into the ground water causing pollution. The only way to know whether this has happened is with a good reliable soil test.
What "salts" are you concerned about? Sometimes "salts" refers to common table salt and sometimes that term refers to the results of an ionic compound resulting from reacting an acid with a base.
Some salts are not good while others are essential to good growth. Being concerned about the buildup of "salts" may be good or it may be unnecessary depending on which "salts" are being discussed.

The U of Mass soil test lab will do a general test for $10 and test soluble salts for an additional $5. Maybe that's the best way to know what's going on with your soil now that you've amended it.
I have never had a problem with SS, and I add plenty of wood ash to my garden and to the compost pile.

More anecdotal info: I have a gardening friend who adds every bit of ash he produces all winter every winter to his garden and he gets great production. I've seen discussions on here about adding all your ash to the compost, and a lot of folks do that. Personally, I wouldn't think of it as a contaminant at all.

Your soil test reveals what would be expected -- that the ash raised the ph. (I throw in a band of it with my peas in the spring, since they like high PH). So adding sulphur should have helped bring it down to where you want it. Just don't plant blueberries there :)

This post was edited by elisa_Z5 on Thu, Feb 27, 14 at 9:48

OK, it's spread out, plants are growing well around it, and you added sulfur. Those are the right things to do. Sulfur takes time to work, I'd keep an eye on the pH (and make sure you sample correctly, i.e. a composite and not just one trowel full from one spot, and use a good calibrated meter or a lab). If it needs more sulfur you can do that.

I would not try to leach anything out without testing to determine whether anything is actually in excess. Otherwise you're chasing shadows.

This post was edited by toxcrusadr on Fri, Feb 28, 14 at 10:23

The original poster is in Canada and sending a soil sample across international borders is just not done, so suggesting
UMASS for a soil test is out of the question.

This post was edited by kimmsr on Fri, Feb 28, 14 at 7:31

Curses! My plot to encourage international soil smuggling has been uncovered . . .

We have narrowly averted being insidiously invaded by the Tundra Turnip Termite! The regulations have reason you know.

Yes, but now my contract with Turnip Assassins, Inc., has been terminated.

I'm guessing their assassinations are perfectly bloodless.