Tooties I would presume that you would add the Potash to the soil before planting, so that your plants will not burn. Potash is very high in salt. I would sprinkle some now and wait at least a couple of weeks or better yet a month before you start setting your plants in to be on the safe side. Not sure when you would have to reapply, you'll have to keep on taking soil test to make sure.

Yes, livestock manure does have some nitrogen, phosphorus, and potash but not much compared to synthetic fertilizers and hence must be applied in much greater quantities. Also keep in mind that aged manure leaches nutrients when it rains. But manure is still a good thing to add, it's rich in organic matter/humus and thus improves the soil's capacity to absorb and store water.

Sharon