if you use hardwood ash as a potassium source you have the added benefits of the ash such as increased microbial activity, gotta be careful with the ph tho.Carl Carlson
If one opted for K-Mag (aka Sul-Po-Mag, Sulfate of Potash Magnesia, langbeinite, et al) you would get the same benefit that you do with epsom salts (magnesium and sulphur) plus you would have a 21% Potassium (K) profile.
HTH
CC