Potassium Status of Temperate Region Soils

Abstract

The potassium in a given soil is a reflection of the parent materials of the soil, degree of weathering, and amount of potassium fertilizer added minus losses due to crop removal and erosion and leaching. Micaceous minerals and their weathering products are the most important source of plant-available potassium in a soil system. Parent material, mineral and soil weathering, and cropping patterns all exert an influence on soil potassium levels, which in turn are reflective of the soil potassium status. That fraction of potassium available to plants, however, is dependent on the dynamics existing between the various potassium-bearing phases and, perhaps more important, the rate of transfer between these phases. Specialty crops such as vegetables and tobacco are always first to receive potassium, both because of high requirements and because the high investment made makes the cost of potassium insignificant.