I don't know what options are for liquid, but I really like potash in the starter.  John, do you put you potash on in the fall or spring.  It take about 6 months for potash to break down.  We are dry, but do vrt potash in the fall and put a 8-12-20 down in a 2x2.  I like to have lots of potash close to the plant in case of a dry year.  If it's really dry, potassium is very, very critical for a corn plant.