Producers Blog

You’re reading Part 2 of a 4-part series. Start the series here.

Let’s start with Potassium (K).

Potassium is derived from weathered soil minerals, such as clay. Typically, higher K levels will be in fields with higher clay content; in contrast, deficient K levels tend to be found in more sandy fields. Most soils contain large quantities of K, but it is not usually all available. K is an essential plant nutrient identified with overall plant vigor. Potassium helps plants activate enzymes, draw water into roots (helping with Nitrogen uptake), produce phosphate molecules and CO2, and translocate sugars.

It is also responsible for the opening and closing of the leaf stomata. The stomates serve as entryways for water and other elements in the leaf (i.e. transpiration). Because of these responsibilities it has been theorized that adequate levels of K provide a higher level of drought tolerance and disease resistance versus deficient fields.

Recommended soil test levels: Soil test recommendations differ regionally but optimum soil test levels would be above 250ppm. Deficient soil test levels would be less than 200ppm.

Deficiency characteristics: Lower leaves are affected first. The plant has a slower rate of growth and the leaf edges and tips become dry and scorched with yellowing stripes. Plant lodging becomes a concern as the corn plant matures.

Crop Removal: There is approximately .23lbs of K removed per bushel of grain. So, crop removal (from grain) would be 46# of K20 on 200bu/ac of corn.

Check out the whole series:

Part 1: Understanding NPK and Their Effect on Your Field

Part 3: Understanding Phosphorus and Its Effect on Your Field

Part 4: Understanding Nitrogen and Its Effect on Your Field

Ward, Raymond C., Ph.D. “Ward Laboratories, Inc.: WardGuide.” Ward Laboratories, Inc.: WardGuide. Ward Laboratories, Inc., n.d. Web. 29 Nov. 2016.