Fertilizer Potassium to Replace Plant Potassium Removal In Burley Tobacco.

Potassium fertilization of high value crops such as burley tobacco generally exceeds that which soil testing would deem adequate. We established a K rate experiment on four soils in Western North Carolina over two years to identify a fertilization rate adequate to replace soil K removed by a previous burley crop. Although soils varied in soil test K at the initiation of the experiment, reduction in soil K concentration during the growing season and at final harvest were predictable and led to a suggested replacement amount of fertilizer to maintain adequate soil K for subsequent crops. Potassium uptake by the burley crop ranged from 145 to 172 kg K ha^-1.  Fertilizer K needed to replace plant K uptake and removal ranged from 45 to 135 kg K₂O ha^-1.  This study indicates that burley tobacco growers can maintain adequate soil potassium by supplying a rate of fertilizer potassium equivalent to that removed by the growing crop.