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Potassium Deficiency Symptoms in Certain Soils in Soybean and Corn (07/07/16)

In the drier areas of the state, notably Cass, Sargent and Richland counties, we have had recent calls and plant sample submission of soybean and corn exhibiting potassium deficiency symptoms.

Potassium Deficiency Symptoms in Certain Soils in Soybean and Corn

In the drier areas of the state, notably Cass, Sargent and Richland counties, we have had recent calls and plant sample submission of soybean and corn exhibiting potassium deficiency symptoms (see images).

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Potassium deficiency may be the result of failure to sample in a zone pattern within a field, where the composite soil sample mixes high K testing soil with low testing soil. In the dry counties, however, the greatest cause is the soil dryness. In our recent, ongoing, research on potassium (K) on corn, we are finding that soils with a high percentage of smectitic clays provide K when moist, but draw the K back in when dry. The soils from which these recently distressed plants come from probably come from fields where the soil is highly smectitic. Soils dominant in illite, such as those in the Sheyenne Delta region (east of Lisbon, through Walcott, Milnor, Leonard, Colfax, Wyndmere), do not respond very much to K fertilizer even when soil test K is very low. Illite clays tend to provide K wet or dry. The best cure for K deficiency symptoms is rainfall, and continually moist, not wet soils. Addition of K as dry 0-0-60, up to 50 pounds of product per acre, followed by rainfall will help to alleviate serious symptoms in soils where K tests are low, although some yield reduction has already taken place.

 

Dave Franzen

NDSU Extension Soil Specialist

 

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