Factors Influencing Potassium Behavior in Soil
The exact mechanism by which some of these factors influence the reaction of potassium in soil is not clearly understood. Some factors that are known to influence potassium in soil are: (1) soil type, (2) temperature, (3) wetting and drying cycles, (4) pH and (5) aeration and moisture.
Fortunately, the majority of Nebraska’s soils abound with minerals that readily release potassium from the non-exchangeable form. Also, most of Nebraska’s soils are rich in potassium-bearing minerals throughout the subsoil, which reduces the influence of factors, such as temperature and moisture content.
Normally, as the topsoil dries, potassium becomes less available to plants. However, with abundant potassium in the subsoil, lack of availability is not a problem. Some of the sandy soils in Nebraska do not have abundant potassium in the subsoil; and, thus, the soil test for potassium is more important on these soils. Excessive moisture tends to reduce aeration and reduces the plant’s ability to absorb potassium. This is more a problem on soils with smaller amounts of available potassium in the topsoil that tend to have wet subsoils in the spring, such as good corn growing soils of Illinois, Indiana, and eastern Iowa. To add to this, wet soils stay cool, and reduced temperature slows down chemical reactions that release potassium to the available form. Cool, wet soils also reduce root proliferation, which reduces plants’ ability to absorb potassium. However, this is not a problem with most of Nebraska’s soils. The article, 'Potassium,' from Nutrient Management for Agronomic Crops in Nebraska, can answer further questions.