Exchangeable Potassium Distribution in IN, MI, OH and PA:

The distribution plots are based on soil tests sent to us by tomato growers and collaborators and show the diversity of soil characteristics of this region. Percentage of farms falling in each range are listed above the distribution bars. Soils that are at lower or higher risk are indicated.

Exchangeable potassium in your soil test may have the units of  lb/ac or ppm. To transform lb/ac to meq/100g (the units of the plot) divide your number by 782 . To transform ppm to meq/100g, divide your number by 391. The units meq/100g and cmol/Kg are equivalents.

To know more about potassium in the soil click on the links below:

http://www.ipipotash.org/slides/kdits1.html : Potassium dynamics in the soil (with slide show) from the International Potash Institute.

http://www.ipipotash.org/slides/kipp1.html : Potassium in plant production (with slide show) from the International Potash Institute.

http://www.ca.uky.edu/sgc/pubs/agr/agr11/agr11.htm :  Soil Extension Publications from the University of Kentucky. 

http://wwwca.uky.edu/agc/pubs/agr/agr11/agr11.htm : The file Potassium in Kentucky Soils brings good information on potassium release and fixation.