I am one who does not like using blended fertilizers. Simply do not trust a blend to spread evenly.

All the fertilizer thought to be needed for a 5 year stand of alfalfa is applied prior to planting in the fall.

I spread murate of potash for up to 300 lbs/A K₂O.
If required I spread up to 1500 lbs of K-Mag for another 300 lbs of K₂O. With this much potash I find I have better percent K, possibly because of the magnesium, maybe because of the sulfur, or maybe because it keeps the chlorine level down.
This amount of potash is half the amount required for 20 tons of alfalfa. A 5 year stand will produce 20 tons or more of alfalfa.

My soil has a 37 to 50 CEC and a lot higher K soil test results than usual. Less than half the removed amount the stand prematurely thins out, and I have not seen any production advantage for a full 1200 lbs/A K₂O

The K-Mag will raise the tissue Mg% 0.02% to 0.04%. Nothing drastic and it does improve the tissue test P/Mg & Ca/Mg & K/Mg ratios. There is a difference between being ok and being good.

With 12% free lime, I deep band 11-37-0. Enough for between 10 and 20 tons of hay, The amount is based on the last tissue test before plowing out the old stand. See last paragraph.

Micro stuff I normally use 12,5 lbs Copper sulfate, 6 lbs Zinc Sulfate, and a pound of a molybdenum product. My fertilizer dealer stirs it all up in his blender with 20 gallons of water per acre.

Depending on the strength of the borax I do blend in enough borax for 4 or 5 lbs of boron in the Potash or the K-Mag.

After the wet year, here, I reduced my alfalfa fields by one. Now I will have 4 in production and one fallow. Every July one will be plowed out and Every September one will be seeded back to alfalfa, after a year fallow.

Works for this soil, climate and management style.