From the Forum board, Bill Wilson was asking about alfalfa needing potash in Nevada:

The short answer is: "very rarely in central Nevada." We have soils that often have abundant K in them. After years and years of farming, if the other nutrient needs of the crop have been met (ie, enough P, S and trace elements), then we sometimes start to see K depletion start. But K depletion, so far as I know, hasn't been much of a problem in central Nevada.

I don't have my soil test results handy just now, but I can tell you that in some places on this outfit, there are K levels over 200 in the soil, occurring naturally.

I can't speak to western NV, over in the Falllon/Yerington/Smith area, where they irrigate with river water on soils that are pretty different than ours in central NV.