Potassium often isn’t the first nutrient on everyone’s mind during a fertility plan but it’s just as essential as nitrogen. In fact, most crops take up just as much or more K2O as N during their lifespan. Fortunately, in typical grain crops a lot of that K is returned to the soil in straw rather than removed in the seed, unless you are haying or baling the straw. For example, three tonnes of alfalfa hay will remove about 180 lbs/ac K2O!
We are already in a window in some parts of western Canada where topdressing hay could be done as snow is gone and growth will resume soon. We’re often asked how efficient broadcast fertilizer is on crops and the results of one alfalfa study gives some insight into the efficiency of potash.
Applied K will typically move 2-3” in a season, so the efficiency in year one is in fact not too bad, likely around 40%. So, if you are struggling with how to get high rates of fertilizer blends through an air drill this spring, broadcasting MOP or Aspire may be a good option. There is no environmental risk to this method and as long as you are putting on a high enough rate (maybe 2-3 yrs worth of K) it is agronomically viable as well.
You could always look at blending a portion of N needs as well through a protected urea source and easily drop 100-200 lbs/ac of product going through an air drill. If nothing else, it’s good to know there are options that don’t compromise the environment or good agronomy.
For more information check out www.mossaicco.com