Potassium Nutrition

These soybean leaves are indicative of a potassium deficiency.

A Controversy that has Cost Farmers Countless Dollars

American farmers have spent nearly $34 billion on Potassium since 19801. Has this investment actually contributed to an increase in yield or crop quality? Not according to a recent peer reviewed research study authored by S.A. Kahn, R.L. Mulvaney and T.R. Ellsworth that found that after a survey of more than 2,100 yield response trials it was confirmed that Potassium Chloride (KCl) fertilization is unlikely to increase crop yield. Contrary to the instilled perception of KCl as a valuable commodity, more than 1,400 field trials predominately documented a detrimental effect of this fertilizer on the quality of major food, feed and fiber crops, with serious implications for soil productivity and human health.

In other words, adding potassium very rarely improved yield or soil quality and they even found that it produced a net negative effect on yield and quality.

False Assumptions

Many assumptions made by those making potassium recommendations are either not true, or they inadequately describe potassium nutrition system in the soil/plant continuum. These false assumptions include:

  1. Exchangeable potassium tests have the ability to predict season-long potassium availability to the crop.
  2. Excess potassium does not negatively affect yield.  
  3. Other pools of potassium in the soil do not affect potassium nutrition.
  4. Neglecting to add potassium causes soil potassium to diminish, resulting in the soil becoming ‘worn out.’
  5. Soil potassium levels can be increased by applying potassium. 

How Potassium Works

Thank you for your interest in this article.

The full content of this article is available to members only. Please create an account to read the full article.