There are some good comments made above. At the risk of repeating....

1) a Starter fertilizer is intended to get the corn crop out of the ground. It is not intended to fertilize season-long.

2) The max N+K for starter fertilizer for corn should be 70 lbs/acre.  You are not going to get enough K applied in the starter following this guideline.

3) For a dairy farm that pulls off a lot a forages, I would expect you also have a lot of manure to put back on.  Are you getting manure applied on all fields where forages are harvested, especially where corn silage is harvested?

4) This should go without saying, but I am going to ask.... Are you soil testing on a regular basis?  IF you have fields where forages (corn silage) are harvested and manure is not applied back, these fields should have frequent soil testing, if for no other reason than to monitor soil K levels.

5) Do you have specific issues related to K levels in your crop?  Are you suspecting that you are not getting enough K into your plants?  If so, are you plant tissue testing to determine when these specific issues are occurring?

6) Has your neighbor put out plots with and without 4-10 gal Liquid Gold to determine if he is getting an economic yield response to his starter fertilizer use?   His corn may look good without starter ... or maybe it won't.  Strip trials should show whether it pays.