Potassium is Critical

Often, the first time I sample for a client, potassium is below critical levels.  Potassium is one of the three macro-nutrients we apply regularly in fertilizer.  Several years ago, University of Illinois Professor Mulvaney came out with the notion that we do not need potassium fertilizer.  It has been my experience that crops do respond to potassium when soil test levels are below 230 pounds per acres.  Ideal levels are considered to be 300 to 400 pounds per acre in Illinois. Potassium is critical to help weather a drought.  Levels need to be high because availability goes down when soil is dry.

No-Till Farmer published an article out of Michigan that calls Potassium the overlooked nutrient.  You better not overlook it if you are going for high alfalfa yields.  Potassium is not currently an environmental concern, but over application can be lost on soil exchange sites.  Most people say that there is no need to apply over 300 pounds per acre unless you are growing a high demand crop.