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Northern Illinois Agriculture

University of Illinois Extension
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Potassium deficiency symptoms in corn and soybean

Posted by Russel Higgins -

"Why are we seeing so many symptoms of Potassium deficiency in our corn and soybean fields?" This was a question posed to Dr. Fabian Fernandez, Soil and Fertility Specialist in the Department of Crop Sciences at the University of Illinois at the recent NIARC Agronomy Day. In his response, Fabian shared that the symptoms were likely due to the dry conditions and the plants inability to reach the potassium in the soil.

From a recent article authored by Dr. Fernandez,

"The reason this happens is that pore space in the soil contains water and air. Plant-available potassium ions are dissolved in the soil water or attached to soil particles ready to come into solution as the plant needs them. When there is sufficient water in the soil, the potassium ions dissolved in water have to travel (by diffusion) only a short distance to be taken up by the crop.

As the soil dries out, the pore space fills with air. The potassium ion has to travel across a larger distance to reach the root because it cannot diffuse through air. Increased diffusion time can cause important reductions in potassium availability to corn during vegetative stages when potassium demands are large.

Under dry conditions, the soil is unable to keep up with the crop demand even though there might be sufficient potassium in the soil"

Fabian's article Water Stress and nutrient deficiency can be read in its entirety here

This morning I had the opportunity to visit with the Kane County Corn Growers at their mid-summer scouting meeting. Shared comments at the meeting made me aware that in areas bordering Wisconsin and now moving south spider mites are becoming active. If our dry weather pattern continues be aware of spider mite damage by first scouting the edges of your soybean fields.


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