My situation may not fit your's. At one time in a fit I spread 2050 lbs/A 0-0-60, prior to planting alfalfa.
Worked well.

Read some horror stories and next time I used 500 lbs/A MOP & 1500 lbs/A K-Mag. Worked too well for my needs

Next applied 500 + 500 MOP & K-Mag, Worked well.
I was shooting for 2.40% K in the tissue analysis.

Now I apply 200 lbs MOP & 100 lbs K-Mag as a top dress going into our ANNUAL SUMMER DROUGHT.

Plus boron to taste. Plus copper sulfate, plus a very little Moly.

Now all based on plant analysis.