Oklahoma State University

Potassium - NPK


Plants take up potassium as the potassium ion (K+).  Potassium within plants is not synthesized into compounds and tends to remain in ionic form in cells and plant tissue.  Potassium is essential for photosynthesis, starch formation and translocation of sugars within plants.  It is necessary for the development of chlorophyll, although it is not part of its molecular structure.
The main functions of potassium in plants are in the translocation of sugars and its involvement in photosynthesis.

Potassium Defficiency Corn

Picture by George Rehm and Michael Schmitt, University of Minnesota


Severe K deficiency was observed in soybean plant in North Central to North Eastern OK in the summer of 2009. Most of these fields were planted wet (which created compaction and poor root growth), had experience a expend cool wet period (reducing K availability and uptake), and had very low Soil Test K levels. Once the warm weather hit the bean took off and the roots and soil could not support the growth. Note lower leaves show the deciency, new leave are green.

Roots following planter rowPlant with poor root growth

K def Soybean leavesK defiecent field with 2 planting dates

K def Bean field





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