Answer: The drastic solution would be to remove soil and use the soil elsewhere as a light topdressing application. Then replace the soil in the planting bed with a new mix.
If it were mine, I would add about 6 inches of compost and mix it in well. When your soil is high in organic matter nutrient excesses are not so detrimental to plants. I would drench it good once or twice to leach out all the excess salts and then go ahead with my garden.
Nitrogen tends to not stay around long and will likely need to be applied this season. You can probably stay away from other fertilizer nutrients for at least a year or two.
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